HYDROXYACETOPHENONE

WHAT IS HYDROXYACETOPHENONE?

Hydroxyacetophenone, also known as 4-Hydroxyacetophenone, 4-Acetylphenol and Piceol, is an aromatic organic compound containing a phenolic hydroxyl group and an acetyl group attached to a benzene ring. In cosmetic and personal care raw-material terminology, Hydroxyacetophenone commonly refers to 4-Hydroxyacetophenone, in which the hydroxyl and acetyl groups occupy para positions on the aromatic ring. 4'-Hydroxyacetophenone is therefore also known as p-Hydroxyacetophenone, para-Hydroxyacetophenone, 4-Acetylphenol, p-Acetylphenol and Piceol. The systematic chemical name 1-(4-hydroxyphenyl)ethanone describes the same molecular structure represented by CAS No. 99-93-4.

The chemical structure of p-Hydroxyacetophenone is important to its technical performance. 4-Hydroxyacetophenone’s phenolic hydroxyl group contributes to antioxidant behavior and hydrogen-bonding capability, while the carbonyl-containing acetyl group influences polarity, molecular interactions and physical properties. Hydroxyacetophenone is best understood as a multifunctional formulation ingredient rather than simply as another conventional preservative.

In modern cosmetic systems, 4-HAP is frequently used to support preservation while simultaneously providing antioxidant functionality. This distinction matters because a preservative booster and a conventional preservative do not necessarily perform the same function. p-Hydroxyacetophenone can improve the overall robustness of a properly designed preservation system, but finished-product microbiological protection must still be demonstrated through appropriate testing. The antioxidant activity of 4-Hydroxyacetophenone is associated with its phenolic molecular structure.

Phenolic compounds can interact with reactive radical species, helping reduce oxidative chain reactions that can affect sensitive ingredients and the overall quality of a cosmetic formulation. Oxidative degradation can contribute to unwanted changes in color, odor, fragrance profile and the stability of oils or sensitive active ingredients. Incorporating Hydroxyacetophenone into an appropriate antioxidant strategy can therefore support the maintenance of formulation quality during storage.

Piceol, also known as p-Acetylphenol, 4-HAP and 1-(4-hydroxyphenyl)ethanone, can also be valuable where formulators are developing sensitive-skin products or formulations intended to use multifunctional preservation concepts. Instead of increasing the concentration of one conventional preservative without considering the rest of the system, the formulation scientist can combine complementary mechanisms. The effectiveness of Hydroxyacetophenone depends on the surrounding formulation.

Concentration, solvent environment, pH, primary preservative, glycols, surfactants, oils, polymers, botanical ingredients and packaging can all affect the behavior of the final system. For this reason, two products containing the same percentage of p-Hydroxyacetophenone do not necessarily have the same preservation performance. Challenge testing and stability evaluation should be performed on the actual finished formulation.

4-Hydroxyacetophenone is also useful from an ingredient-efficiency perspective. A multifunctional raw material capable of contributing to both antioxidant protection and preservation support can help reduce unnecessary formulation complexity when it is technically appropriate. 4'-Hydroxyacetophenone is not restricted to one type of cosmetic product.

Hydroxyacetophenone can be evaluated in aqueous systems, emulsions, surfactant formulations, gels, serums and other personal care products when suitable processing and solubility conditions are provided. One practical characteristic of p-Hydroxyacetophenone is its crystalline physical form. The ingredient must be properly dissolved or incorporated because inadequate processing can result in undissolved particles or recrystallization after the formulation cools.

Processing conditions should therefore be developed experimentally rather than copied without validation from another formula. A clear serum, for example, can require different solubility control from an opaque cream or rinse-off cleanser. Commercial Hydroxyacetophenone products may also differ in purity and impurity control.

The fact that two suppliers offer CAS No. 99-93-4 does not automatically mean that the materials have identical color, residual impurities, water content or processing behavior. Technical purchasing should consequently evaluate the complete specification rather than the chemical name alone. This is especially important for premium cosmetics, transparent products, sensitive-skin formulations and products distributed in several regulatory markets.

COMMON NAMES AND SYNONYMS OF HYDROXYACETOPHENONE

Hydroxyacetophenone can be encountered under several chemical names, historical names and commercial search terms. The most frequently used names for CAS No. 99-93-4 include 4-Hydroxyacetophenone, 4'-Hydroxyacetophenone, p-Hydroxyacetophenone, para-Hydroxyacetophenone, 4-HAP and Piceol. 4-Acetylphenol and p-Acetylphenol are also established names for the same para-substituted molecule.

The substance is additionally known as 1-(4-hydroxyphenyl)ethanone, 1-(4-hydroxyphenyl)ethan-1-one or Ethanone, 1-(4-hydroxyphenyl)-. Other recognized names include 4-Hydroxyphenyl methyl ketone, p-Hydroxyphenyl methyl ketone, Methyl p-hydroxyphenyl ketone and p-Oxyacetophenone. These names reflect the same underlying molecular structure from different chemical naming conventions.

Common Product and Chemical Names:

Hydroxyacetophenone

4-Hydroxyacetophenone

4'-Hydroxyacetophenone

p-Hydroxyacetophenone

para-Hydroxyacetophenone

Hydroxyacetophenone, para

4-HAP

p-HAP

4-Acetylphenol

p-Acetylphenol

Para-Acetylphenol

4-Acetophenol

p-Acetophenol

Piceol

1-(4-Hydroxyphenyl)ethanone

1-(4-Hydroxyphenyl)ethan-1-one

Ethanone, 1-(4-hydroxyphenyl)-

4-Hydroxyphenyl methyl ketone

p-Hydroxyphenyl methyl ketone

Methyl p-hydroxyphenyl ketone

Methyl 4-hydroxyphenyl ketone

p-Oxyacetophenone

Phenol, p-acetyl-

These names are useful for technical searches, supplier qualification and raw-material equivalency projects. A manufacturer searching for "p-Hydroxyacetophenone supplier," "4-HAP cosmetic grade," "Piceol CAS 99-93-4" or "4-Acetylphenol supplier" may therefore be looking for the same chemical raw material. Not every compound containing the words Hydroxy and Acetophenone is the same substance.

Positional isomers must be distinguished because moving the hydroxyl group to a different position on the aromatic ring changes the chemical identity and physical behavior. For purchasing purposes, CAS No. 99-93-4 provides an important identity checkpoint. Specifying both Hydroxyacetophenone and CAS 99-93-4 substantially reduces ambiguity when requesting a quotation or evaluating a replacement raw material.

CAS NO, EC / EINECS NO AND INCI NAME

Product name: Hydroxyacetophenone

Common chemical name: 4-Hydroxyacetophenone

Alternative chemical name: 4'-Hydroxyacetophenone

Systematic name: 1-(4-Hydroxyphenyl)ethan-1-one

CAS No: 99-93-4

EC / EINECS No: 202-802-8

INCI Name: HYDROXYACETOPHENONE

Molecular formula: C8H8O2

Molecular weight: Approximately 136.15 g/mol

Chemical class: Aromatic hydroxy ketone / phenolic ketone

Physical state: Solid at normal ambient conditions

Typical appearance: White to off-white crystalline powder, crystals or flakes depending on grade

Primary cosmetic function: Antioxidant

Common formulation role: Multifunctional preservative booster / preservation synergist

CAS No. 99-93-4 identifies the para-hydroxy substituted acetophenone structure discussed throughout this page. The EC / EINECS number 202-802-8 provides an additional European chemical identity reference for 4'-Hydroxyacetophenone. The INCI name HYDROXYACETOPHENONE is the relevant cosmetic ingredient designation. Cosmetic manufacturers should nevertheless confirm the supplier's current INCI and regulatory documentation before approving a commercial grade.

The molecular formula C8H8O2 represents eight carbon atoms, eight hydrogen atoms and two oxygen atoms. The calculated molecular weight is approximately 136.15 g/mol. Chemical identity is only the first stage of raw-material qualification. Purity, individual impurities, water content, physical appearance, melting behavior and documentation should also be evaluated according to the intended application.

CHEMICAL STRUCTURE AND MOLECULAR PROPERTIES OF HYDROXYACETOPHENONE

Hydroxyacetophenone, also known as 4-Hydroxyacetophenone, consists of a benzene ring substituted with a hydroxyl group and an acetyl group in para positions. This arrangement gives the molecule both phenolic and ketone functionality within a compact aromatic structure. The phenolic hydroxyl group can donate a hydrogen atom during radical-scavenging reactions. The aromatic system can then help distribute and stabilize the resulting electronic structure, which contributes to the antioxidant behavior associated with p-Hydroxyacetophenone.

The acetyl group contains a carbonyl bond and adds another polar region to the molecule. As a result, 4-Acetylphenol contains both hydrogen-bond donor and hydrogen-bond acceptor functionality. This balance between an aromatic ring and polar functional groups influences solubility. Piceol does not behave like a highly water-soluble polyol, but neither does it behave like a purely hydrophobic hydrocarbon.

Hydrogen bonding also contributes to the crystalline behavior of 4-HAP. Intermolecular interactions between molecules help explain why the material is normally supplied as a crystalline solid and has a clearly defined melting region. The phenolic group is weakly acidic.

Ionization behavior changes as pH approaches the compound's dissociation region, although normal cosmetic formulation decisions should be based on practical supplier guidance and finished-system testing rather than theoretical pKa alone. At the molecular level, Hydroxyacetophenone therefore offers a useful combination of aromatic stability, phenolic antioxidant functionality and moderate polarity. These characteristics underpin many of its cosmetic applications.

PHYSICAL AND CHEMICAL PROPERTIES OF HYDROXYACETOPHENONE

Hydroxyacetophenone is generally supplied as a white to off-white crystalline solid. Depending on crystallization, milling and commercial presentation, the product may appear as powder, crystals or flakes.

General technical characteristics:

Physical appearance: White to off-white crystalline powder, crystals or flakes

Chemical identity: 4-Hydroxyacetophenone

CAS No: 99-93-4

EC / EINECS No: 202-802-8

INCI: HYDROXYACETOPHENONE

Molecular formula: C8H8O2

Molecular weight: Approximately 136.15 g/mol

Physical state: Solid

Chemical family: Phenolic aromatic ketone

Typical melting region: Approximately 109–113°C for certain high-purity commercial grades

Purity: Common high-purity cosmetic grades may be specified at 99% or higher

Water content: Grade dependent

Solubility: Dependent on solvent, temperature and concentration

Odor: Generally low for suitable high-purity cosmetic grades

The melting range can provide useful information during identity and purity evaluation. A commercial specification around 109–113°C is encountered for high-purity p-Hydroxyacetophenone, although the actual supplier specification should always control incoming quality decisions. Purity specifications also vary between suppliers.

Some commercial cosmetic grades are specified at not less than 99.0% by HPLC, while other specialized grades may offer Hydroxyacetophenone concentrations of 99.8% or higher. These differences do not automatically establish which product is better for every formulation. A technical buyer should compare the complete impurity profile, consistency, documentation and actual formulation performance.

Important purchasing parameters may include assay, appearance, melting point, loss on drying, water content, residue on ignition, phenol content, individual unidentified impurities and total impurities. Additional requirements can be established according to the manufacturer's internal quality standard. Physical form can influence handling and dissolution speed even when chemical purity is equivalent.

Powder, crystals and flakes can have different charging and dissolution characteristics because of their different surface areas. The information above should therefore be treated as general technical guidance rather than as an Ataman Kimya product specification. Current TDS and batch-specific COA information should be requested for the actual Hydroxyacetophenone grade being considered.

HOW DOES HYDROXYACETOPHENONE WORK AT THE MOLECULAR LEVEL?

Hydroxyacetophenone’s technical value begins with the phenolic hydroxyl group attached to its aromatic structure. This group can participate in radical-scavenging reactions and helps explain why the ingredient is used as an antioxidant in cosmetic formulations. Free radicals can participate in oxidative chain reactions affecting oils, fragrances, pigments and sensitive active ingredients. By contributing to antioxidant defense, 4-Hydroxyacetophenone can help slow processes that would otherwise contribute to undesirable changes in the formulation.

The effect should not be interpreted as complete protection against every oxidative mechanism. Oxygen exposure, ultraviolet or visible light, heat, transition metals, peroxide-containing raw materials and unsaturated lipids can all influence oxidation. The ingredient listed as "Hydroxyacetophenone, para" is therefore most useful as one component of a broader antioxidant strategy. Depending on the product, this strategy may also involve tocopherol, suitable chelating agents, other antioxidants, controlled raw-material quality and protective packaging.

Hydroxyacetophenone’s preservation-support behavior represents another important molecular-level benefit. 4-HAP can enhance the effectiveness of suitable preservation systems and is consequently described commercially as a preservative booster or preservation synergist. Preservation boosters are especially useful when the formulation scientist wants to combine several complementary antimicrobial mechanisms. The objective is to design a robust system rather than simply increase one conventional preservative without considering the rest of the formula.

Hydroxyacetophenone can be combined with other preservation ingredients and multifunctionals where compatibility has been demonstrated. Examples may include phenoxyethanol, 1,2-hexanediol, caprylyl glycol, ethylhexylglycerin, pentylene glycol and suitable organic-acid systems. The actual synergy depends on the complete formulation.

A combination that performs effectively in a facial toner may behave differently in a surfactant-rich shampoo or lipid-rich emulsion. At the physical level, dissolution and crystallization are also molecular interaction problems. Hydroxyacetophenone molecules must remain adequately solvated within the formulation to prevent crystal formation during cooling and storage.

The solvent environment is therefore a critical part of formulation design. Glycols, alcohols, water, temperature and the presence of other ingredients can influence the ability of the system to maintain 4-Acetylphenol in solution. The combination of antioxidant functionality, preservation synergy and controllable formulation behavior explains why p-Hydroxyacetophenone has become an important multifunctional ingredient in modern personal care development.

WHAT PROBLEMS CAN HYDROXYACETOPHENONE HELP SOLVE?

Hydroxyacetophenone is principally selected when formulators need to improve product protection without unnecessarily complicating the formulation. Its multifunctional character allows antioxidant and preservation-support requirements to be considered together.

Oxidative Instability

Cosmetic oils, fragrances and sensitive actives can undergo oxidation during manufacturing or storage. Oxidation may lead to undesirable odor, color change and deterioration of product quality. 4-Hydroxyacetophenone contributes phenolic antioxidant activity and can therefore support the formulation's defense against oxidative degradation. The final antioxidant system should nevertheless be matched to the particular oxidation risks of the product.

Weak Preservation Margin

A formulation may contain an antimicrobial system that requires additional robustness. p-Hydroxyacetophenone can be investigated as a preservative booster to improve overall product protection. The appropriate concentration and combination should be established experimentally. Preservative efficacy testing remains necessary because preservation performance cannot be predicted reliably from the ingredient list alone.

Need to Optimize Conventional Preservative Levels

Some formulation projects aim to reduce reliance on higher levels of conventional preservatives. Piceol can support this objective when incorporated into a complementary preservation strategy. Any reduction in another preservative should be justified by microbiological data. There is no universal substitution ratio between Hydroxyacetophenone and a conventional preservative.

Sensitive-Skin Formulation Challenges

Products positioned for sensitive skin still require adequate microbiological protection. The preservation system must therefore balance product safety, tolerability, formulation compatibility and consumer expectations. 4-HAP can be useful in this development approach because it provides preservation support together with antioxidant and skin-conditioning functionality.

Excessive Formulation Complexity

Adding a separate raw material for every individual technical function can produce unnecessarily complicated formulations. Multifunctional ingredients provide an opportunity to obtain several useful effects from one component. Para-Acetylphenol can contribute antioxidant protection while also strengthening the preservation strategy. This can improve ingredient efficiency when the molecule is technically suitable for the formulation.

Recrystallization and Solubility Problems

Hydroxyacetophenone itself can create a formulation challenge if it is not correctly dissolved. A poorly designed process can result in visible crystals after production or during low-temperature storage. This problem can be addressed by optimizing solvent selection, concentration, processing temperature, order of addition and cooling conditions. Stability testing should confirm that p-Hydroxyacetophenone remains appropriately incorporated throughout the intended shelf life.

Preservative-Induced Emulsion Challenges

Some multifunctional antimicrobial materials have strong amphiphilic character and can influence emulsion interfaces. Depending on the formulation, this can affect viscosity or physical stability. 4-Acetophenol provides a different molecular profile from long-chain glycols and certain surfactant-like boosters. This difference can be advantageous in some systems, although compatibility should still be confirmed experimentally.

WHICH INDUSTRIES USE HYDROXYACETOPHENONE?

Hydroxyacetophenone is particularly important in cosmetics and personal care, but its aromatic chemical structure also makes 4-Hydroxyacetophenone relevant to specialty chemical and synthesis applications. The appropriate grade should always be selected according to final use.

Main application sectors include:

Cosmetics

Personal care

Skin care

Hair care

Sun care

Body care

Sensitive-skin formulations

Facial care

Cleansing products

Makeup and color cosmetics

Deodorant and personal hygiene products

Cosmetic formulation development

Specialty chemical synthesis

Fine chemical applications

Research and development

Pharmaceutical or intermediate-related chemical applications where an appropriate grade is specified

The technical requirements differ significantly between sectors. A cosmetic formulator may prioritize INCI status, purity, color and preservation performance, while a chemical synthesis operation may focus on assay, reaction purity and impurity profile. For this reason, a product described only as "99% Hydroxyacetophenone" should not automatically be assumed to be appropriate for every application. The intended market, documentation and manufacturing controls should be evaluated together.

USE OF HYDROXYACETOPHENONE IN COSMETICS AND PERSONAL CARE

Hydroxyacetophenone has its most commercially important application area in cosmetics as a multifunctional ingredient. 4-HAP is valued for antioxidant functionality, preservation boosting and its suitability for a wide variety of formulation formats. Potential cosmetic applications include facial serums, moisturizers, creams, lotions, toners, essences, gels, masks and cleansing products. p-Hydroxyacetophenone can also be evaluated in sun care, body care, hair care and scalp formulations. In these products, the ingredient often performs behind the scenes rather than serving as the primary consumer-facing active. Its purpose is to help maintain product quality and support a robust formulation architecture.

This technical role is important because formulation stability is essential to consumer experience. A premium active ingredient provides limited value if the finished product develops an unacceptable odor, color change or microbiological problem during storage. Hydroxyacetophenone therefore contributes to the quality infrastructure of a cosmetic formulation. Its multifunctionality is especially attractive when formulators want fewer raw materials to perform several complementary functions.

USE OF HYDROXYACETOPHENONE IN SKIN CARE

Hydroxyacetophenone is used in skin care formulations that frequently contain water, humectants, oils, botanical extracts, proteins, peptides and other materials that create both oxidative and microbiological challenges. 4-Hydroxyacetophenone can support product protection in this complex environment. Typical applications include moisturizing creams, anti-aging serums, facial lotions, barrier-support formulations, toners, essences, masks and after-sun products. Piceol can also be incorporated into products designed around sensitive-skin concepts when the overall formulation supports that positioning.

In an antioxidant serum, p-Hydroxyacetophenone may complement ingredients such as Vitamin C derivatives, Vitamin E or other antioxidant actives. Each antioxidant operates within a particular chemical environment, so combinations can be more useful than expecting one molecule to address every oxidative pathway. In moisturizing emulsions, Hydroxyacetophenone can simultaneously contribute antioxidant and preservation-support functions.

The formulation scientist should verify its dissolution and ensure that cooling does not produce crystals. Transparent serums require especially careful evaluation. Even small quantities of recrystallized 4-Acetylphenol may become visually noticeable and can reduce consumer acceptance despite otherwise acceptable product performance.

USE OF HYDROXYACETOPHENONE IN HAIR CARE

Hydroxyacetophenone can be incorporated into suitable shampoos, conditioners, hair masks, scalp serums, leave-in treatments and styling products. Its principal technical value remains antioxidant and preservation support. Hair care products can create distinctive preservation challenges because they often contain surfactants, cationic materials, polymers, proteins, botanical extracts and fragrances. These components can influence the distribution and availability of antimicrobial ingredients.

p-Hydroxyacetophenone should therefore be tested in the actual hair care base rather than assumed to perform identically to a skin care emulsion. The finished shampoo or conditioner should undergo appropriate stability and microbiological testing. Scalp products are another relevant application. Lightweight aqueous scalp serums can benefit from multifunctional ingredients that provide product protection without unnecessarily increasing oiliness or formulation complexity.

USE OF HYDROXYACETOPHENONE IN SUN CARE

Hydroxyacetophenone is used in sun care formulations that can contain UV filters, emollients, film-forming polymers, antioxidants, emulsifiers and preservation components. This complexity creates a demanding environment for both physical and chemical stability. 1-(4-Hydroxyphenyl)ethanone may be used to support antioxidant protection and preservation in suitable sunscreen formulations. It should not be confused with a UV filter and does not replace approved ultraviolet-filtering ingredients.

4-Hydroxyacetophenone’s role is instead to support the formulation surrounding the UV-filter system. p-Hydroxyacetophenone can contribute to the overall product-protection strategy while the approved UV filters provide the intended ultraviolet protection. Sun care products may experience elevated temperatures during consumer use. Stability studies should therefore consider realistic temperature exposure, packaging and the possibility of Hydroxyacetophenone recrystallization.

USE OF HYDROXYACETOPHENONE IN CLEANSING PRODUCTS

Hydroxyacetophenone can be considered for facial cleansers, cleansing gels, shower gels, liquid washing products and other water-containing rinse-off formulations. Surfactant systems require special attention during preservation development. Micelles can influence how preservation ingredients distribute through the formulation.

The nominal concentration of an antimicrobial component therefore does not always represent the freely available concentration responsible for microbial control. 4-HAP can support the preservation system, but the final cleanser should be challenge tested. Surfactant concentration, pH, botanical ingredients and packaging can all change preservation requirements.

USE OF HYDROXYACETOPHENONE IN SENSITIVE-SKIN FORMULATIONS

Hydroxyacetophenone use in sensitive-skin formulation is not simply a matter of removing conventional preservatives. A poorly preserved product can create a substantially greater problem than the presence of an appropriately selected preservation system.

1-(4-Hydroxyphenyl)ethan-1-one is useful because it gives formulators another mechanism for designing effective product protection. p-Hydroxyacetophenone can complement antimicrobial ingredients while simultaneously providing antioxidant functionality. This flexibility can help R&D teams optimize the overall preservation system instead of relying on unnecessarily high levels of one component. Finished-product tolerability and preservation must still be verified independently.

HYDROXYACETOPHENONE AS AN ANTIOXIDANT

Hydroxyacetophenone’s antioxidant behavior is closely associated with its phenolic hydroxyl group. This structural feature allows 4-Hydroxyacetophenone to participate in reactions involving free radicals. Oxidative deterioration can occur throughout a product's life cycle, beginning with raw-material storage and continuing through manufacturing, filling, warehousing and consumer use.

Heat, light, oxygen and trace metals can accelerate these reactions. p-Hydroxyacetophenone can contribute to antioxidant defense by interrupting some radical-driven oxidation processes. This can help protect formulation components from premature deterioration.

4'-Hydroxyacetophenone should not be expected to replace every other antioxidant. Tocopherol, for example, can be particularly useful in lipid phases, while chelating agents can help control transition-metal-catalyzed oxidation. A robust antioxidant strategy may therefore combine 4-HAP with complementary ingredients and suitable packaging.

The correct combination depends on the chemistry of the formulation. The antioxidant value of Piceol can also be relevant in formulas containing botanical extracts and other sensitive materials. These formulations should nevertheless undergo accelerated stability testing because natural extracts can introduce additional oxidation and color-stability challenges.

HYDROXYACETOPHENONE AS A PRESERVATIVE BOOSTER

Hydroxyacetophenone as a preservative booster describes one of the ingredient's most important commercial uses. A preservative booster helps improve the effectiveness of a broader preservation system. 4-Hydroxyacetophenone should therefore be distinguished from a traditional preservative used as the principal antimicrobial component.

Piceol’s greatest formulation value often appears through synergy with other ingredients. Potential preservation partners may include phenoxyethanol, 1,2-hexanediol, caprylyl glycol, ethylhexylglycerin, pentylene glycol and appropriately designed organic-acid systems. The suitability of each combination depends on the formulation.

The ingredient listed as "Ethanone, 1-(4-hydroxyphenyl)-" can help formulation scientists build systems using several complementary mechanisms. This approach may provide better flexibility than attempting to obtain all required antimicrobial performance from one molecule. The concentration of each component should be optimized experimentally.

There is no technically responsible universal equation stating that a particular percentage of 4-HAP replaces a fixed percentage of another preservative. Challenge testing is therefore central to preservation development. A successful test demonstrates the behavior of the complete finished product rather than merely the theoretical activity of its individual raw materials.

WHY USE HYDROXYACETOPHENONE IN MODERN PRESERVATION SYSTEMS?

Hydroxyacetophenone is used in modern personal care formulations that often require preservation systems satisfying several objectives simultaneously. The system must control microorganisms while remaining compatible with the desired texture, fragrance, packaging and consumer positioning. Hydroxyacetophenone gives the formulator additional flexibility because its value extends beyond antimicrobial support. Its antioxidant functionality allows one raw material to contribute to two important product-protection objectives.

4-Hydroxyphenyl methyl ketone also differs structurally from glycol-based multifunctional boosters. This can provide another tool when a formulation does not respond optimally to a preservation strategy based entirely on diols or amphiphilic ingredients. Multifunctionality can also support formulation simplification.

Reducing unnecessary raw-material complexity may improve inventory management and make troubleshooting easier, provided the final system remains technically robust. The objective should never be to remove preservatives purely for marketing purposes. The correct objective is to develop the safest and most stable finished product using an efficient combination of ingredients.

BENEFITS OF HYDROXYACETOPHENONE FOR MANUFACTURERS

Hydroxyacetophenone provides manufacturers with formulation flexibility. One ingredient can contribute antioxidant protection while simultaneously supporting the preservation system. This dual function can be particularly valuable for companies developing multiple product formats. 4-HAP may be evaluated across serums, creams, lotions, cleansers, hair products and sun care rather than being limited to one narrow application.

Another advantage is the possibility of optimizing the total preservative system. Where challenge testing confirms adequate protection, p-Hydroxyacetophenone may allow the formulator to design a more balanced combination of antimicrobial ingredients. Manufacturers may also benefit from formulation simplification.

Using multifunctional ingredients can reduce the need to introduce separate raw materials solely to achieve individual secondary functions. Procurement efficiency can improve when one well-qualified ingredient is used across several product families. However, the economic benefit should be evaluated using cost in use rather than raw-material price alone.

A higher-purity Hydroxyacetophenone grade may cost more per kilogram but provide advantages in color, consistency or processing. Conversely, paying for unnecessary specification limits that provide no measurable formulation benefit may not be economically justified. The correct commercial decision therefore combines formulation performance, quality consistency, documentation, supply security and total cost.

BENEFITS OF HYDROXYACETOPHENONE FOR THE END USER

Hydroxyacetophenone provides benefits that consumers generally experience indirectly through the quality of the finished cosmetic product. Product stability and microbiological protection are essential parts of overall consumer safety and satisfaction. 4-Hydroxyacetophenone can contribute to maintaining formulation quality by supporting antioxidant and preservation systems. This may help the product retain acceptable appearance, odor and performance throughout its intended life when the overall formulation is correctly designed.

4'-Hydroxyacetophenone is also used in formulations developed for sensitive-skin concepts. The suitability of the finished product for sensitive skin depends on the entire formulation and should not be attributed to Hydroxyacetophenone alone. The end-user benefit is therefore best understood as improved formulation robustness rather than as one isolated cosmetic claim.

HYDROXYACETOPHENONE SOLUBILITY AND PROCESSING

Hydroxyacetophenone solubility is one of the most important practical considerations in formulation. The crystalline raw material must be adequately dissolved or otherwise appropriately incorporated to prevent visible particles and inconsistent distribution. p-Hydroxyphenyl methyl ketone has limited solubility in water at ambient conditions compared with highly water-soluble humectants.

Solubility can improve with temperature and through the use of suitable solvent systems. Commercial technical guidance may recommend dissolution in heated water or compatible solvents such as certain glycols or alcohol-containing phases. The exact procedure should follow the supplier's TDS and should be confirmed in laboratory trials.

A common development mistake is to add 4-HAP directly to a cold finished formulation without checking whether the available solvent environment can dissolve the required concentration. The product may initially appear acceptable while crystals develop later. Cooling behavior is therefore as important as initial dissolution.

A formulation that dissolves Hydroxyacetophenone at elevated temperature can become supersaturated as temperature falls. Low-temperature storage should be included in stability testing. Transparent serums, toners and essences deserve particular attention because small crystals are readily visible.

Glycol-containing systems may offer improved incorporation options. Propanediol, pentylene glycol, butylene glycol or other formulation solvents can be evaluated according to compatibility and product concept. The formulator should record the temperature at which the ingredient becomes fully dissolved.

Mixing time, cooling rate and the sequence of addition should also be standardized during scale-up. Manufacturing at plant scale can produce different thermal and mixing conditions from laboratory preparation. A successful 500-gram laboratory batch should therefore be confirmed during pilot and production-scale trials.

TYPICAL USE LEVEL OF HYDROXYACETOPHENONE

Hydroxyacetophenone is normally used at relatively low concentrations because it functions as a high-value multifunctional component rather than a bulk formulation ingredient. Commercial recommendations vary according to grade, application and the other preservation ingredients present. Development ranges encountered for cosmetic p-Hydroxyacetophenone may extend from approximately 0.05% into the region of 1% or somewhat higher depending on the specific commercial grade and intended function.

Many formulation concepts evaluate the ingredient within the sub-1% range. These figures are starting points rather than universal specifications. The supplier's recommended use level should be considered together with challenge-test performance, solubility and regulatory requirements.

A higher concentration does not automatically produce a proportionally stronger benefit. Solubility limitations, cost and interactions with other ingredients should be considered when optimizing 4-HAP. The most efficient concentration is the lowest level that consistently achieves the required technical performance as part of the complete formulation system.

INITIAL FORMULATION APPROACHES FOR HYDROXYACETOPHENONE

Hydroxyacetophenone can be evaluated in different product categories using the following preliminary R&D starting frameworks. They are not validated commercial formulas, finished manufacturing instructions or guarantees of preservation performance. Each formulation should undergo appropriate stability, compatibility, safety and microbiological evaluation. The exact Hydroxyacetophenone concentration and preservation system should be adjusted according to the supplied grade and experimental results.

EXAMPLE: HYDROXYACETOPHENONE ANTIOXIDANT FACIAL SERUM

Purpose: To evaluate 4-Hydroxyacetophenone in a lightweight water-based serum requiring antioxidant protection and preservation support.

Preliminary starting framework:

Purified Water: q.s. to 100%

Glycerin: 3.0–5.0%

Propanediol: 3.0–5.0%

Hydroxyacetophenone: 0.2–0.5%

Niacinamide: 2.0–5.0%

Panthenol: 0.5–1.0%

Sodium Hyaluronate: 0.05–0.20%

Chelating Agent: 0.05–0.20%

Rheology Modifier: as required

Primary Preservation System: as required

pH Adjuster: q.s.

The 4-HAP should be dissolved in a suitable heated aqueous or solvent-containing phase before final cooling. Clarity, pH, viscosity, color and recrystallization should be monitored during stability testing. A challenge test should be performed on the final serum. The presence of Hydroxyacetophenone does not by itself demonstrate adequate preservation.

EXAMPLE: HYDROXYACETOPHENONE MOISTURIZING CREAM

Purpose: To evaluate p-Hydroxyacetophenone in an oil-in-water facial cream requiring antioxidant and preservation-support functionality.

Preliminary starting framework:

Purified Water: 65–75%

Glycerin: 3–5%

Emollient System: 10–15%

Emulsifier System: 2–5%

Fatty Alcohol / Consistency Agent: 1–3%

Hydroxyacetophenone: 0.2–0.5%

Chelating Agent: 0.05–0.2%

Skin-Conditioning Actives: as required

Preservation System: as required

pH Adjuster: q.s.

The 4-Hydroxyacetophenone should be incorporated through a phase that provides complete dissolution. The final cream should be evaluated for viscosity, centrifuge stability, high-temperature storage, freeze-thaw behavior and crystal formation. Microbiological preservation must be confirmed in the finished emulsion. Changes in oil phase or emulsifier system can alter preservative behavior and should trigger appropriate reassessment.

EXAMPLE: HYDROXYACETOPHENONE TONER

Purpose: To formulate a transparent or translucent aqueous toner with antioxidant and preservation-support properties.

Preliminary starting framework:

Purified Water: q.s. to 100%

Propanediol: 3–6%

Glycerin: 2–4%

Hydroxyacetophenone: 0.2–0.5%

Panthenol: 0.2–1.0%

Chelating Agent: 0.05–0.20%

Water-Soluble Active Ingredients: as required

Preservation System: as required

pH Adjuster: q.s.

Because visual clarity is important, the dissolution behavior of p-Hydroxyacetophenone should be monitored carefully. Samples should be stored at both normal and reduced temperatures to identify delayed crystallization. The formulation should also be inspected after temperature cycling. A toner that remains clear immediately after manufacture can still develop crystals during storage if the solvent capacity is insufficient.

EXAMPLE: HYDROXYACETOPHENONE SENSITIVE-SKIN LOTION

Purpose: To evaluate 4-HAP in a fragrance-free lotion designed around a balanced preservation strategy.

Preliminary starting framework:

Purified Water: q.s. to 100%

Glycerin: 3–5%

Propanediol: 2–4%

Light Emollient System: 8–12%

Emulsifier: 2–4%

Hydroxyacetophenone: 0.2–0.5%

Panthenol: 0.5–1.0%

Barrier-Support Ingredients: as required

Chelating Agent: as required

Complementary Preservation System: as required

pH Adjuster: q.s.

The purpose of this approach is not to create an inadequately preserved "preservative-free" lotion. The technical objective is to use complementary mechanisms to achieve reliable protection with a formulation suitable for the intended consumer group.

EXAMPLE: HYDROXYACETOPHENONE CLEANSING GEL

Purpose: To evaluate Piceol in a surfactant-containing rinse-off formulation.

Preliminary starting framework:

Purified Water: q.s. to 100%

Primary Surfactant System: 8–12%

Secondary Surfactants: 3–6%

Glycerin: 2–4%

Hydroxyacetophenone: 0.2–0.5%

Chelating Agent: 0.05–0.20%

Rheology Modifier: as required

Preservation System: as required

Fragrance: optional

pH Adjuster: q.s.

Surfactant micelles can influence antimicrobial availability. Challenge testing is therefore particularly important when transferring a preservation concept from a cream or serum into a cleansing product.

EXAMPLE: HYDROXYACETOPHENONE HAIR CONDITIONER

Purpose: To evaluate p-Hydroxyacetophenone in a rinse-off conditioning emulsion.

Preliminary starting framework:

Purified Water: q.s.

Cationic Conditioning System: 2–5%

Fatty Alcohols: 2–5%

Emollient: 1–3%

Humectant: 2–4%

Hydroxyacetophenone: 0.2–0.5%

Hair-Conditioning Actives: as required

Preservation System: as required

Fragrance: as required

pH Adjuster: q.s.

Cationic surfactants and conditioning polymers can alter preservation behavior. The final conditioner should therefore be assessed rather than assuming that data from a facial emulsion can be transferred directly.

EXAMPLE: HYDROXYACETOPHENONE SUN CARE EMULSION

Purpose: To investigate 4-Hydroxyacetophenone as part of the antioxidant and preservation strategy of a sunscreen formulation.

Preliminary framework:

Water Phase: according to system

UV Filter Phase: according to applicable formulation and regulations

Emollients: as required

Emulsifier System: as required

Hydroxyacetophenone: 0.2–0.5%

Antioxidant System: as required

Chelating Agent: as required

Preservation System: as required

Rheology Modifier: as required

pH Adjuster: q.s.

Hydroxyacetophenone is not a UV filter and should not be counted toward SPF or UVA protection. Its role in this example is formulation support rather than ultraviolet absorption performance. Sun care products require specialized efficacy, stability and regulatory evaluation. Any preliminary formulation must therefore be developed further before commercialization.

HYDROXYACETOPHENONE COMPARED WITH PHENOXYETHANOL

Hydroxyacetophenone and Phenoxyethanol are frequently discussed together because both can appear within cosmetic preservation systems. Their primary technical roles, however, are not identical. Phenoxyethanol is widely used as a conventional cosmetic preservative. 4-Hydroxyacetophenone is more appropriately characterized as a multifunctional antioxidant and preservative booster. This difference means that the two molecules can be complementary. p-Hydroxyacetophenone may strengthen a preservation system containing phenoxyethanol while contributing additional antioxidant functionality.

A formulator should not assume that 0.5% Hydroxyacetophenone can automatically replace a predetermined percentage of phenoxyethanol. Any reduction should be justified by finished-product microbiological testing. An important advantage of 4-HAP is multifunctionality.

Phenoxyethanol's commercial value is primarily preservation, whereas Hydroxyacetophenone combines preservation support with phenolic antioxidant behavior. Phenoxyethanol may nevertheless provide stronger direct preservative functionality in many systems. The appropriate choice therefore depends on whether the formulation requires a primary preservative, a booster or a combination of both.

HYDROXYACETOPHENONE COMPARED WITH ETHYLHEXYLGLYCERIN

Hydroxyacetophenone is compared here with Ethylhexylglycerin, a multifunctional glyceryl ether frequently used to support cosmetic preservation. Its molecular structure is substantially different from the aromatic phenolic structure of p-Hydroxyacetophenone. Ethylhexylglycerin has amphiphilic characteristics and can provide skin-conditioning and deodorizing benefits in addition to preservation support.

Hydroxyacetophenone contributes a distinct antioxidant mechanism through its phenolic structure. The two ingredients should therefore not be viewed simply as direct substitutes. Their different structures can make them complementary within carefully designed preservation systems.

4-HAP can be advantageous when antioxidant functionality is a major formulation objective. Ethylhexylglycerin may be preferable where its specific sensory, deodorizing or amphiphilic properties are required. The decision should be based on challenge-test performance, physical stability, sensory impact, solubility, cost in use and the intended product positioning.

HYDROXYACETOPHENONE COMPARED WITH CAPRYLYL GLYCOL

Hydroxyacetophenone is compared here with Caprylyl Glycol, another common multifunctional preservation-support ingredient. It provides humectant and emollient properties and can contribute to antimicrobial system performance. Hydroxyacetophenone has a different molecular structure and does not provide the same emollient profile. Its distinctive advantage is the combination of phenolic antioxidant activity and preservation synergy.

Caprylyl Glycol can sometimes influence emulsion behavior because of its amphiphilic structure. p-Hydroxyacetophenone may interact differently with an emulsion system, although this does not guarantee superior stability in every formula. Some formulations can benefit from combining both ingredients. Laboratory testing should determine whether the combination provides a useful performance advantage.

HYDROXYACETOPHENONE COMPARED WITH 1,2-HEXANEDIOL

Hydroxyacetophenone is compared here with 1,2-Hexanediol, which is widely used as a multifunctional solvent, humectant and preservation booster. It is liquid and offers different processing characteristics from crystalline Hydroxyacetophenone. The liquid physical form of 1,2-Hexanediol can make incorporation straightforward. By comparison, 4-HAP requires attention to dissolution and potential recrystallization.

Methyl p-hydroxyphenyl ketone offers antioxidant functionality that distinguishes it from a simple glycol-based booster. This can be advantageous in products where oxidation control is part of the formulation objective. The two ingredients can also be used together. Their different molecular mechanisms may provide complementary preservation performance depending on the system.

HYDROXYACETOPHENONE COMPARED WITH PENTYLENE GLYCOL

Hydroxyacetophenone is compared here with Pentylene Glycol, which is valued as a humectant, solvent and multifunctional preservation-support ingredient. It can also contribute significantly to the sensory and hydration profile of a cosmetic formulation. p-Hydroxyacetophenone is used at lower levels and does not replace the bulk humectancy provided by Pentylene Glycol. Its principal distinction is the combination of antioxidant and preservation-support properties.

A formulator requiring substantial humectancy may therefore select Pentylene Glycol regardless of whether Hydroxyacetophenone is present. The ingredients address overlapping but not identical formulation requirements. When used together, the glycol can also contribute to the solvent environment available to 4-Hydroxyacetophenone. The actual solubility and stability of the final formulation should still be confirmed experimentally.

HYDROXYACETOPHENONE COMPARED WITH TOCOPHEROL

Hydroxyacetophenone and Tocopherol both provide antioxidant functionality, but their physical and chemical behavior differs considerably. Tocopherol is lipophilic and is particularly useful for protecting lipid phases. 4-HAP has a smaller phenolic aromatic structure and is incorporated through different formulation phases. Its additional value as a preservative booster distinguishes it from Tocopherol.

These ingredients should therefore be considered complementary rather than mutually exclusive. A formulation containing oxidation-sensitive oils may benefit from an oil-phase antioxidant while Hydroxyacetophenone contributes additional antioxidant and preservation-support functions. Antioxidant selection should always be based on the location and mechanism of the oxidative risk within the formulation.

ADVANTAGES OF HYDROXYACETOPHENONE OVER COMPETING MOLECULES

Hydroxyacetophenone has functional density as one of its principal advantages. A relatively low concentration can contribute to more than one important formulation objective. Compared with a single-purpose antioxidant, 4-HAP offers preservation-support functionality. Compared with a conventional preservative, it offers a phenolic antioxidant contribution.

Compared with glycol-based boosters, p-Hydroxyacetophenone provides a distinct aromatic phenolic mechanism and does not need to serve primarily as a bulk humectant. This allows formulators to select it for product protection rather than for texture or hydration alone. The solid crystalline form also allows the ingredient to be supplied at high active concentration without carrying a large solvent fraction. This can be advantageous for transportation, storage and formulation flexibility.

Hydroxyacetophenone’s main processing disadvantage compared with liquid glycols is the need for controlled dissolution. This is manageable when the formulation contains an appropriate solvent system and manufacturing process. Methyl 4-hydroxyphenyl ketone can also be attractive for formulations seeking a short and purposeful ingredient list.

One multifunctional component can contribute antioxidant and preservation-support functions without requiring separate raw materials for every secondary role. No competitor comparison should be interpreted as meaning that 4-Hydroxyacetophenone is universally superior. The technically best ingredient is the one that satisfies the target preservation, stability, sensory, regulatory and cost requirements of the actual formulation.

KEY CONSIDERATIONS WHEN USING HYDROXYACETOPHENONE

Hydroxyacetophenone chemical identity is the first consideration. The cosmetic material should be confirmed as the intended 4-Hydroxyacetophenone associated with CAS No. 99-93-4. The second consideration is grade.

Cosmetic applications should use a product with suitable purity, impurity control and documentation rather than assuming that every technical grade is interchangeable. Solubility should be investigated during formulation development. The final solvent environment must maintain p-Hydroxyacetophenone in the required state throughout production and storage.

Processing temperature should be controlled and documented. Excessive heat should be avoided where unnecessary, while sufficient temperature may be required to achieve complete dissolution. Cooling conditions deserve equal attention.

Recrystallization often becomes apparent only after the formulation cools or experiences low-temperature storage. The preservation system should be evaluated as a whole. Hydroxyacetophenone should not be expected to compensate automatically for poor manufacturing hygiene, unsuitable packaging or an inadequate antimicrobial system.

pH should be controlled because it influences the complete formulation. Polymer viscosity, organic-acid preservatives, surfactants and other ingredients can all respond to pH changes. Raw-material changes should trigger appropriate review.

Replacing one Hydroxyacetophenone supplier with another should not be treated as a purely administrative change if specifications or impurity profiles differ. Challenge testing, stability testing and compatibility evaluation remain essential development tools. Testing should establish performance in the manufacturer's own product.

QUALITY CONTROL AND PURCHASING CRITERIA FOR HYDROXYACETOPHENONE

Hydroxyacetophenone technical purchasing should begin with a clear definition of intended use. A cosmetic manufacturer has different requirements from a fine-chemical synthesis operation.

Information recommended for review before purchase:

Product name

Chemical identity

CAS No. 99-93-4

EC / EINECS No. 202-802-8

INCI name

Manufacturer

Country of origin

Manufacturing site where required

Quality grade

Assay

Analytical method

Appearance

Melting range

Water content or loss on drying

Residue on ignition

Individual impurities

Total impurities

Phenol content where specified

Heavy metals where required

Residual solvents where applicable

Packaging

Net weight

Shelf life or retest period

Storage conditions

TDS

SDS

COA

Regulatory statements

Batch traceability

Change-control information where available

The assay is important but should not dominate the entire purchasing decision. A 99.8% product is not automatically preferable to a 99.0% product if both satisfy the formulation requirements and the latter provides better consistency, documentation or supply reliability. Conversely, a high-value transparent serum may justify tighter color and impurity limits.

Quality specifications should reflect real technical needs rather than arbitrary numbers. A representative COA can help buyers understand normal batch results before qualification. Once commercial supply begins, batch-specific COAs should be checked according to the company's incoming quality procedure.

HOW TO SELECT THE RIGHT HYDROXYACETOPHENONE GRADE

Hydroxyacetophenone grade selection by cosmetic manufacturers should normally begin by confirming that the proposed grade is intended and documented for personal care applications. An industrial synthesis grade should not automatically be substituted merely because the CAS number is identical. Purity should be matched to the formulation.

High-purity grades can be especially useful where color, odor and impurity control are important. Transparent products may require additional attention to physical appearance and dissolution behavior. Any insoluble material or discoloration can be more visible in a toner or serum than in an opaque cream.

For sensitive-skin products, manufacturers may place greater emphasis on impurity profile and supplier quality systems. The final formulation must still undergo its own safety assessment. Global products can require additional regulatory documentation.

The supplier should be able to provide appropriate information for the target markets where relevant. The correct grade is therefore not simply the material with the highest assay. It is the grade that provides the required chemical identity, physical properties, documentation, consistency and commercial supply profile.

TDS, SDS AND COA FOR HYDROXYACETOPHENONE

The Technical Data Sheet, Safety Data Sheet and Certificate of Analysis serve different purposes. All three are important during Hydroxyacetophenone qualification. The TDS normally describes general technical characteristics such as identity, appearance, specification, recommended applications, processing guidance and storage. It helps R&D and purchasing teams understand how the product is intended to be used.

The SDS focuses on safe handling. It contains information relevant to hazard identification, first aid, fire response, accidental release, exposure control, storage and disposal. The COA is batch specific. It records analytical results for the actual production batch supplied to the customer.

A TDS cannot replace a COA because typical or specification values do not prove the result of a particular batch. Likewise, a COA does not contain the complete workplace safety information provided by the SDS. Technical buyers should therefore request all required documents rather than asking simply whether a "certificate" is available.

STORAGE AND HANDLING OF HYDROXYACETOPHENONE

Hydroxyacetophenone should be stored according to the current supplier recommendations. Original packaging should normally remain tightly closed in a dry, appropriately ventilated storage environment. The product should be protected from contamination and unnecessary exposure to moisture. Clean and dry equipment should be used for sampling, weighing and transfer.

After opening, the container should be resealed promptly. Leaving crystalline p-Hydroxyacetophenone exposed to the production environment can increase the risk of contamination or changes in material condition. Storage temperature requirements should be taken from the actual supplier documentation.

Generic internet information should not override the SDS or TDS for the purchased grade. Material stored beyond its stated shelf-life or retest period should be handled according to the company's quality procedure. Continued use should be based on appropriate assessment rather than assumption.

SAFETY INFORMATION FOR HYDROXYACETOPHENONE

Hydroxyacetophenone should be handled according to the current Safety Data Sheet supplied with the commercial material. Workplace controls should be determined through an appropriate risk assessment. During weighing and transfer, operators should minimize unnecessary dust generation.

Suitable protective equipment should be used where required by the SDS and site procedures. Eye contact, skin exposure and inhalation of airborne powder should be controlled using appropriate industrial hygiene practices. Ventilation or local extraction may be appropriate during repeated bulk handling.

Spill procedures should prevent unnecessary dispersal of powder. Waste should be managed according to applicable regulations and the supplier's safety information. The fact that Hydroxyacetophenone is used in cosmetics does not mean that concentrated raw material should be handled as though it were a finished cosmetic product.

Occupational exposure and consumer exposure are different scenarios. Finished-product safety must also be assessed separately. The safety of a cosmetic formulation depends on concentration, exposure route, product type and the other ingredients present.

HYDROXYACETOPHENONE AND pH

The useful formulation range of Hydroxyacetophenone provides flexibility in personal care systems. Commercial multifunctional grades are used across a broad cosmetic pH region. p-Oxyacetophenone contains a phenolic hydroxyl group and therefore has acid-base behavior at sufficiently alkaline conditions. The complete formulation should nevertheless be designed around practical stability and preservation requirements rather than theoretical ionization alone.

pH strongly affects many complementary preservatives. Organic acids, for example, can depend on the concentration of their undissociated form for antimicrobial effectiveness. The pH selected for a Hydroxyacetophenone formulation should therefore satisfy the requirements of the entire ingredient system. Skin compatibility, polymer rheology, surfactant stability and active-ingredient stability must also be considered.

HYDROXYACETOPHENONE AND CHALLENGE TESTING

Hydroxyacetophenone use does not remove the need for preservative efficacy testing to demonstrate the microbiological robustness of many water-containing cosmetic products. The presence of 4-HAP does not eliminate this requirement. A challenge test examines the ability of the finished formulation to control specified microorganisms under defined test conditions.

The result reflects the combined effect of the entire formulation. Hydroxyacetophenone concentration is only one variable. pH, water activity, surfactants, oils, packaging, botanical extracts, proteins and the primary preservation system can all change the outcome. A preservation system that passes in a facial cream cannot automatically be assumed to pass in a shampoo.

Even apparently small formulation changes can influence antimicrobial availability. Challenge testing should therefore be integrated into development rather than treated as a final administrative step. Early testing can prevent expensive reformulation after packaging and production parameters have already been fixed.

HYDROXYACETOPHENONE AND FORMULATION STABILITY

Hydroxyacetophenone formulation quality involves chemical stability, physical stability and microbiological stability as separate but interconnected aspects. Hydroxyacetophenone can contribute to chemical and microbiological protection while the formulation still requires independent physical stabilization. An emulsion needs an appropriate emulsifier and rheological structure. 4-HAP cannot compensate for an inadequate emulsifier system. A suspension requires suitable particle stabilization.

Hydroxyacetophenone is not a universal suspension agent. A transparent serum requires adequate solvent capacity. The formulation must keep p-Hydroxyacetophenone and other dissolved ingredients from crystallizing during storage. Accelerated stability should monitor appearance, odor, color, pH, viscosity and phase behavior.

Low-temperature studies are particularly useful for identifying crystallization risk. Packaging compatibility should also be assessed. Product protection depends on the interaction between formulation, container and expected consumer use.

HYDROXYACETOPHENONE PRICE AND COMMERCIAL EVALUATION

Hydroxyacetophenone price depends on more than the molecular identity of CAS No. 99-93-4. Grade, purity, manufacturer, country of origin, packaging, order quantity and commercial terms can all influence the quotation. Higher-purity cosmetic grades may carry different pricing from general industrial material.

Additional quality controls and regulatory documentation can also influence cost. Freight can be important, particularly for smaller quantities. Comparing ex-works prices without considering delivery conditions can create misleading procurement conclusions.

Annual volume and order pattern also affect commercial evaluation. A customer purchasing regular pallet quantities may receive a different supply structure from a laboratory purchasing small packs. The most useful comparison is cost in use.

Because Hydroxyacetophenone is normally used at a relatively low percentage, a difference in kilogram price may have a modest impact on the cost of the finished formulation. Supply consistency can be more economically important than a small unit-price difference. A formulation failure, delayed production campaign or unplanned requalification can cost considerably more than the raw-material saving achieved through an unreliable source.

WHAT SHOULD BE CONSIDERED WHEN PURCHASING HYDROXYACETOPHENONE?

Hydroxyacetophenone purchasing should begin by confirming the exact chemical identity. Hydroxyacetophenone intended for the applications discussed on this page should correspond to 4-Hydroxyacetophenone, CAS No. 99-93-4. The intended application should then be stated. Cosmetic, personal care, fine chemical and research applications can require different grades and documentation.

Before purchase, clarify:

Application sector

Final product

Required grade

Required purity

INCI requirement

CAS number

EC / EINECS number

Appearance requirement

Melting range

Impurity limits

Water or loss-on-drying limit

Residual-solvent requirements

Heavy-metal requirements where applicable

Packaging size

Order quantity

Annual demand

Country of destination

Required TDS

Required SDS

Required COA

Regulatory documentation

Origin requirement

Manufacturer requirement

Shelf-life requirement

Lead time

If the project involves replacing an existing Hydroxyacetophenone, providing the current product's TDS and recent COA can make technical comparison more efficient. A CAS match alone is not sufficient for establishing equivalence. Pilot testing is recommended before large-scale substitution. Solubility and crystallization behavior can change even when the headline assay is similar.

HYDROXYACETOPHENONE SUPPLY FROM ATAMAN KIMYA

Hydroxyacetophenone, also listed as "Phenol, p-acetyl-", is a technically important multifunctional raw material used primarily for antioxidant activity and preservation support in cosmetics and personal care formulations. Selecting an appropriate product requires evaluation of chemical identity, grade, purity, physical properties, documentation and intended application. Companies evaluating Hydroxyacetophenone supply from Ataman Kimya can share their application requirements so that the relevant product specification and commercial supply options can be reviewed. Providing detailed technical information at the quotation stage helps avoid unsuitable grade selection.

A useful Hydroxyacetophenone inquiry includes:

Intended application

Final product category

Required quantity

Estimated annual volume

Required purity

Required grade

Current product if replacement is required

Packaging preference

Destination

Required technical documentation

Regulatory documentation requirements

For equivalency projects, customers can provide the TDS or COA of the currently used p-Hydroxyacetophenone. Comparing actual specifications is more technically meaningful than comparing only CAS numbers. Current manufacturer, origin, stock status, packaging, specification, lead time and commercial conditions should be confirmed with Ataman Kimya during the quotation process. This application-based purchasing approach allows the supplier and customer to discuss Hydroxyacetophenone as a functional raw material rather than merely as a commodity identified by one chemical name.

FREQUENTLY ASKED QUESTIONS ABOUT HYDROXYACETOPHENONE

What is Hydroxyacetophenone? 
Hydroxyacetophenone is an aromatic phenolic ketone used particularly in cosmetic and personal care formulations. The commercial cosmetic ingredient discussed here is primarily 4-Hydroxyacetophenone, CAS No. 99-93-4, which is valued as an antioxidant and preservative booster. 

What is the CAS number of Hydroxyacetophenone?
The CAS number for 4-Hydroxyacetophenone is 99-93-4. Because other positional hydroxyacetophenone isomers exist, technical buyers should confirm the CAS number rather than relying on the shortened chemical name alone. 

What is the EINECS number of Hydroxyacetophenone? 
The EC / EINECS number for 4'-Hydroxyacetophenone is 202-802-8.

What is the INCI name of Hydroxyacetophenone?
The cosmetic INCI name is HYDROXYACETOPHENONE.

What is the molecular formula of Hydroxyacetophenone?
The molecular formula of p-Hydroxyacetophenone is C8H8O2.

What is the molecular weight of Hydroxyacetophenone?
The molecular weight is approximately 136.15 g/mol.

What is another name for Hydroxyacetophenone? 
Common names include 4-Hydroxyacetophenone, 4'-Hydroxyacetophenone, p-Hydroxyacetophenone, para-Hydroxyacetophenone, 4-HAP, 4-Acetylphenol, p-Acetylphenol and Piceol. 

Is Piceol the same as Hydroxyacetophenone? 
Piceol is a recognized name for 4-Hydroxyacetophenone, CAS No. 99-93-4.

Is 4-Acetylphenol the same as Hydroxyacetophenone?
4-Acetylphenol is another name used for the para isomer 4-Hydroxyacetophenone. 

Is p-Hydroxyacetophenone the same as 4-Hydroxyacetophenone? 
Yes. The prefix "p" means para and identifies the relative positions of the hydroxyl and acetyl groups on the aromatic ring.

Is 3-Hydroxyacetophenone the same as Hydroxyacetophenone CAS 99-93-4? 
No. 3-Hydroxyacetophenone is a different positional isomer and should not be considered interchangeable with 4-Hydroxyacetophenone CAS No. 99-93-4. 

Is 2-Hydroxyacetophenone the same as 4-Hydroxyacetophenone?
No. They contain the same types of functional groups but the groups occupy different positions on the aromatic ring, creating different chemical substances. 

What does Hydroxyacetophenone do in cosmetics?
Hydroxyacetophenone is principally valued for antioxidant activity and its ability to support preservation systems. Depending on the commercial grade and formulation, it can also be positioned as a multifunctional skin-conditioning ingredient. 

Is Hydroxyacetophenone an antioxidant?
Yes. Its phenolic structure allows 4-HAP to participate in free-radical scavenging and antioxidant processes. 

Is Hydroxyacetophenone a preservative?
Hydroxyacetophenone is commonly described as a preservative booster or preservation synergist rather than automatically being treated as a complete standalone preservation system. 

What is a Hydroxyacetophenone preservative booster? 
A preservative booster is an ingredient that supports the effectiveness of a broader antimicrobial system. p-Hydroxyacetophenone can be combined with suitable preservation ingredients to improve overall formulation protection.

Can Hydroxyacetophenone replace phenoxyethanol? 
It should not automatically be treated as a one-to-one replacement. Hydroxyacetophenone can support systems containing phenoxyethanol and may help formulators optimize the complete preservation system, but challenge testing is required.

Can Hydroxyacetophenone be combined with phenoxyethanol? 
Yes. p-Hydroxyacetophenone can be evaluated with phenoxyethanol as part of a complementary preservation system. 

Can Hydroxyacetophenone be combined with 1,2-Hexanediol?
Yes. 4-HAP and 1,2-Hexanediol can provide complementary preservation-support properties because their molecular structures and formulation roles differ. 

Can Hydroxyacetophenone be combined with Caprylyl Glycol? 
Yes, provided the combination is compatible with the complete formulation. The final product should be evaluated for physical stability and preservation performance. 

Can Hydroxyacetophenone be combined with Ethylhexylglycerin?
Yes. Hydroxyacetophenone and Ethylhexylglycerin can be considered in multifunctional preservation systems where their combined properties are technically useful. 

Can Hydroxyacetophenone be combined with Pentylene Glycol? 
Yes. Pentylene Glycol can contribute humectancy, solvent properties and preservation support, while 4-Hydroxyacetophenone provides antioxidant and complementary preservation-boosting functionality. 

What is the typical use level of Hydroxyacetophenone? 
Use levels depend on the commercial grade and formulation. Cosmetic development commonly evaluates relatively low concentrations, frequently within the sub-1% region, while individual supplier recommendations can extend outside this range. 

Is Hydroxyacetophenone water soluble? 
Hydroxyacetophenone has limited aqueous solubility at ambient conditions compared with highly water-soluble polyols. Temperature and the presence of suitable solvents can significantly influence practical incorporation. 

How do you dissolve Hydroxyacetophenone?
4-HAP can be incorporated using an appropriate heated phase or compatible solvent system according to supplier guidance. Glycols, alcohol-containing systems or heated aqueous phases may be evaluated depending on the formulation.

Why does Hydroxyacetophenone crystallize in a formulation? 
Crystallization can occur when the concentration exceeds the solvent capacity of the final formulation, particularly as temperature decreases. Solvent composition, concentration and cooling conditions should be optimized.

Can Hydroxyacetophenone be used in clear serums? 
Yes, but complete dissolution and low-temperature stability should be verified. Transparent products make even minor crystallization visually obvious.

Can Hydroxyacetophenone be used in facial creams? 
Yes. 4-Hydroxyacetophenone can be incorporated into suitable oil-in-water and other cosmetic emulsion systems. 

Can Hydroxyacetophenone be used in lotions?
Yes. Its antioxidant and preservation-support functions can be useful in facial and body lotions. 

Can Hydroxyacetophenone be used in toners?
Yes. p-Hydroxyacetophenone can be evaluated in toners and essences when the solvent system maintains adequate solubility. 

Can Hydroxyacetophenone be used in cleansers? 
Yes. Hydroxyacetophenone can support preservation in suitable facial and body cleansing products, although surfactant systems should undergo finished-product challenge testing. 

Can Hydroxyacetophenone be used in shampoo? 
Yes. 4-HAP can be evaluated in shampoo formulations as part of the antioxidant and preservation strategy.

Can Hydroxyacetophenone be used in hair conditioners? 
Yes. It can be incorporated into suitable conditioning emulsions provided solubility, compatibility and preservation are verified.

Can Hydroxyacetophenone be used in sunscreen? 
Yes, as a formulation-support ingredient where appropriate. Hydroxyacetophenone is not a UV filter and does not replace approved sunscreen active ingredients.

Can Hydroxyacetophenone be used in sensitive-skin products? 
It is commonly evaluated in sensitive-skin formulation concepts because of its multifunctional profile. Suitability of the finished product must nevertheless be demonstrated through the complete safety assessment.

Is Hydroxyacetophenone suitable for natural cosmetics? 
Suitability depends on the origin of the commercial grade, the applicable natural-cosmetic standard and supplier documentation. The fact that Piceol occurs in nature does not automatically make every commercially manufactured grade compliant with every natural standard.

What is the melting point of Hydroxyacetophenone? 
High-purity commercial 4-Hydroxyacetophenone grades commonly show melting specifications around approximately 109–113°C. The specification for the actual purchased grade should be used for quality control.

What does Hydroxyacetophenone look like? 
It is typically supplied as a white to off-white crystalline powder, crystals or flakes. 

Is Hydroxyacetophenone a liquid?
No. 4-Hydroxyacetophenone is normally a crystalline solid under standard ambient conditions. 

What purity is available for Hydroxyacetophenone? 
High-purity commercial grades are available. Depending on supplier and application, specifications of 99% or higher are commonly encountered, with some specialized cosmetic grades offering tighter assay requirements. 

Does higher Hydroxyacetophenone purity always mean better performance? 
Not necessarily. Purity is important, but impurity profile, color, water content, batch consistency, documentation and actual formulation performance also matter. 

What should be checked on a Hydroxyacetophenone COA? 
Depending on specification, the COA may include appearance, assay, melting range, loss on drying or water, residue on ignition, individual impurities and total impurities.

What is a Hydroxyacetophenone TDS? 
The Technical Data Sheet provides general information about the commercial grade, including identity, technical properties, recommended applications and sometimes formulation guidance. 

What is a Hydroxyacetophenone SDS?
The Safety Data Sheet provides information for safe handling, storage, exposure control, emergency response and disposal of the raw material. 

Does a COA replace the SDS? 
No. The COA provides batch-specific analytical results, while the SDS provides safety information. The documents serve different purposes. 

How should Hydroxyacetophenone be stored?
It should generally be stored in properly closed original packaging under the conditions specified by the supplier, protected from unsuitable heat, moisture and contamination. 

Does Hydroxyacetophenone need challenge testing? 
Finished cosmetic formulations using Hydroxyacetophenone as part of a preservation system should undergo appropriate preservative efficacy testing according to the manufacturer's quality and regulatory requirements.

Does Hydroxyacetophenone work at every pH? 
It can be used across a useful cosmetic formulation range, but the performance of the entire preservation system remains pH dependent. Supplier guidance and finished-product testing should determine suitability.

Does Hydroxyacetophenone destabilize emulsions? 
Its effect depends on the formulation. 4-HAP has a different molecular profile from amphiphilic glycol-based boosters, but every emulsion should still be tested for viscosity and physical stability. 

Is Hydroxyacetophenone better than Phenoxyethanol?
The two ingredients serve different primary functions and should not be ranked as universal substitutes. Phenoxyethanol is commonly used as a conventional preservative, while Hydroxyacetophenone is valued as an antioxidant and preservation booster. 

Is Hydroxyacetophenone better than Caprylyl Glycol?
The appropriate choice depends on the formulation. Caprylyl Glycol offers humectant and emollient properties together with preservation support, while 4-Hydroxyacetophenone offers phenolic antioxidant functionality and preservation synergy. 

Is Hydroxyacetophenone better than Ethylhexylglycerin?
They provide different technical profiles. A formulator should select or combine them according to preservation performance, sensory requirements, physical stability and cost in use. 

What determines Hydroxyacetophenone price?
Price depends on grade, purity, manufacturer, origin, quantity, packaging, logistics, quality documentation and commercial conditions. 

Should Hydroxyacetophenone be purchased only according to price? 
No. Specification, batch consistency, technical documentation and supply reliability should be evaluated alongside price. 

What grade of Hydroxyacetophenone is suitable for cosmetics? 
A grade supported and documented for cosmetic or personal care applications should be selected. The exact specification should match the requirements of the finished product. 

Can industrial-grade Hydroxyacetophenone be used in cosmetics? 
It should not automatically be assumed suitable. Cosmetic manufacturers should verify purity, impurity controls, documentation and intended-use support before approving any grade. 

Which documents should be requested when buying Hydroxyacetophenone? 
TDS, SDS and batch-specific COA are fundamental documents. Additional regulatory and quality statements may be required according to the application and target market. 

How can a manufacturer change Hydroxyacetophenone supplier? 
The proposed replacement should be compared against the existing product's specification and COA. Laboratory, stability and microbiological testing may be appropriate before full commercial substitution. 

What information should be included in a Hydroxyacetophenone quotation request? 
The request should include application, CAS number, required grade, purity, quantity, packaging, destination and required technical documentation.

Where can Hydroxyacetophenone be sourced? 
Hydroxyacetophenone is supplied through specialty chemical and personal care raw-material distribution channels. Technical buyers should ensure that the proposed product corresponds to CAS No. 99-93-4 and the required grade.

Can Ataman Kimya supply Hydroxyacetophenone? 
Companies evaluating Hydroxyacetophenone supply can contact Ataman Kimya with their required grade, application, quantity, packaging and documentation needs. Current product availability and commercial conditions should be confirmed during the quotation process.

HYDROXYACETOPHENONE – TECHNICAL AND COMMERCIAL SUMMARY

Hydroxyacetophenone is an aromatic multifunctional ingredient used primarily in cosmetics and personal care for antioxidant functionality and preservation support. The commercially important para isomer discussed in cosmetic applications is 4-Hydroxyacetophenone, identified by CAS No. 99-93-4 and EC / EINECS No. 202-802-8. The molecular formula of p-Hydroxyacetophenone is C8H8O2 and its molecular weight is approximately 136.15 g/mol. The cosmetic INCI designation is HYDROXYACETOPHENONE.

4'-Hydroxyacetophenone is also known as p-Hydroxyacetophenone, para-Hydroxyacetophenone, 4-HAP, 4-Acetylphenol, p-Acetylphenol, Piceol and 1-(4-hydroxyphenyl)ethanone. These synonyms appear in chemical databases, supplier documentation and commercial purchasing searches. The molecule contains both a phenolic hydroxyl group and an acetyl functionality attached to an aromatic ring. This structure contributes to antioxidant activity, intermolecular hydrogen bonding, polarity and the crystalline physical form of the raw material.

Hydroxyacetophenone is typically supplied as a white to off-white crystalline solid. Commercial high-purity grades may be available as powder, crystals or flakes depending on manufacturing and finishing processes. Certain high-purity commercial grades have melting specifications in the approximate 109–113°C region. Actual incoming quality limits should always be based on the supplier's current product specification rather than on a generic value.

p-Hydroxyacetophenone functions as an antioxidant through its phenolic structure. The antioxidant properties of 4-Hydroxyacetophenone can contribute to the control of radical-driven oxidation processes that otherwise may affect oils, fragrances, sensitive actives and overall product quality. Hydroxyacetophenone is also widely used as a preservative booster. Rather than being treated automatically as a complete standalone preservative, 4-HAP is normally incorporated into a broader preservation strategy containing complementary antimicrobial mechanisms.

Potential combination partners for Hydroxyacetophenone can include Phenoxyethanol, 1,2-Hexanediol, Caprylyl Glycol, Ethylhexylglycerin, Pentylene Glycol and other suitable preservation components. The correct preservation system depends on the final formulation and its microbiological requirements. Piceol is used in skin care, hair care, sun care, cleansing, body care and sensitive-skin formulations. Relevant product formats include serums, creams, lotions, toners, essences, gels, cleansers, shampoos, conditioners and sunscreens.

One of the main formulation considerations for Hydroxyacetophenone is solubility. The crystalline ingredient should be properly dissolved using an appropriate solvent environment and processing procedure. Heating, glycols, alcohol-containing phases or other compatible solvent strategies may be evaluated according to the supplied 4-Hydroxyacetophenone grade and formulation. The supplier's technical guidance should be followed during process development.

Recrystallization of p-Hydroxyacetophenone should be monitored after cooling. A formulation that appears fully dissolved while hot may develop visible crystals during room-temperature or low-temperature storage. Transparent serums and toners containing Hydroxyacetophenone are especially sensitive to this issue. Stability programs should therefore include visual inspection under appropriate temperature conditions.

Typical cosmetic use levels of Hydroxyacetophenone are relatively low and depend on the commercial product and target function. The technically optimum concentration should be established through formulation trials rather than selected solely from a generic percentage recommendation. Hydroxyacetophenone provides manufacturers with an important multifunctional advantage. One ingredient can support antioxidant protection while simultaneously strengthening a suitable preservation strategy.

This functional combination differentiates p-Hydroxyacetophenone from conventional single-function antioxidants and from primary preservatives. The multifunctional behavior of 4-HAP also distinguishes the molecule from glycol-based boosters whose principal secondary functions may be humectancy or solvent performance. Hydroxyacetophenone should nevertheless not be presented as universally superior to Phenoxyethanol, Ethylhexylglycerin, Caprylyl Glycol, 1,2-Hexanediol or Pentylene Glycol. These molecules provide different properties and can often be complementary.

For a technical buyer, the correct Hydroxyacetophenone purchasing decision depends on more than CAS number. Purity, appearance, melting range, water content, impurity profile, manufacturing consistency, regulatory documentation and supplier reliability should all be evaluated. Technical Data Sheet (TDS), Safety Data Sheet (SDS) and Certificate of Analysis (COA) documentation should be requested during qualification. The TDS provides general technical information, the SDS addresses safe handling and the COA records batch-specific analytical results.

Companies replacing an existing Hydroxyacetophenone grade should compare the current and proposed products using actual specifications. A CAS match does not establish complete functional equivalence between different p-Hydroxyacetophenone commercial grades. Laboratory trials should assess dissolution, appearance, color, pH, viscosity and physical stability. Preservation systems containing 4-Hydroxyacetophenone should undergo appropriate challenge testing before commercial approval.

Storage of Hydroxyacetophenone should follow the supplier's current instructions. Original containers should remain properly closed and protected from contamination and unsuitable environmental conditions. The price of 4-Hydroxyacetophenone varies according to purity, grade, origin, manufacturer, order volume, packaging, logistics and required documentation. Purchasing decisions should therefore compare equivalent grades and calculate the impact at finished-product level.

Hydroxyacetophenone should ultimately be selected according to how reliably the ingredient performs in the customer's actual formulation and manufacturing process. Chemical identity establishes what the raw material is, while formulation testing, quality documentation and consistent supply determine suitability for commercial production. The multifunctional properties of Piceol make it a valuable candidate for cosmetic manufacturers developing antioxidant and preservation-support systems. Appropriate technical qualification helps ensure that the selected 4-Hydroxyacetophenone grade meets the required performance, stability and quality standards.

HYDROXYACETOPHENONE SUPPLY FROM ATAMAN KIMYA

Hydroxyacetophenone supply enquiries with Ataman Kimya should include the intended cosmetic application, required purity, physical form, expected order quantity, destination market and preferred packaging options. p-Hydroxyacetophenone is commonly evaluated for antioxidant functionality and preservation support in skin care, hair care and personal care formulations. Companies seeking a Hydroxyacetophenone supplier should specify the intended formulation, target concentration, solvent compatibility and critical quality parameters to support accurate technical product selection.

For cosmetic-grade Hydroxyacetophenone, technical buyers should request purity specifications, appearance, melting range, moisture content and relevant impurity information. Ask Ataman Kimya to confirm the proposed manufacturer, product origin, current Technical Data Sheet (TDS), Safety Data Sheet (SDS) and batch-specific Certificate of Analysis (COA). When replacing an existing raw material, p-Hydroxyacetophenone and Piceol grades should be evaluated through representative formulation testing to verify dissolution behavior, recrystallization resistance, antioxidant performance and compatibility with the intended preservation system.

Companies searching for a Hydroxyacetophenone supplier, 4-Hydroxyacetophenone price, p-Hydroxyacetophenone cosmetic grade, Piceol CAS 99-93-4 or Hydroxyacetophenone preservative booster can contact Ataman Kimya for technical and commercial supply enquiries. Packaging options, sample availability, stock status, lead times, applicable certifications and commercial conditions should be confirmed for the exact 4-Hydroxyacetophenone grade offered. A verified product specification, reliable quality documentation and transparent purchasing terms help manufacturers select a suitable Hydroxyacetophenone grade that meets their formulation, stability and commercial production requirements.