BUTYLATED HYDROXYTOLUENE (BHT)

Butylated Hydroxytoluene (BHT) is a low-molecular-weight, sterically hindered phenolic antioxidant used to slow oxidative deterioration in oils, polymers and other oxidation-sensitive organic materials. The defined substance is 2,6-di-tert-butyl-4-methylphenol, CAS Number 128-37-0. Commercial BHT is normally supplied as a white crystalline solid, powder, granules or flakes; molten and formulated liquid versions are separate supply forms that require their own handling and composition information.
The antioxidant function of Butylated Hydroxytoluene (BHT) comes primarily from its ability to interrupt radical oxidation chains. Its phenolic hydrogen can be transferred to a reactive radical, while the substituted aromatic structure helps stabilize the resulting phenoxyl radical. Consequently, BHT can delay the development of rancidity, discoloration, viscosity change and loss of material properties when it is compatible with the formulation and present at an effective concentration.
Butylated Hydroxytoluene (BHT) finds applications in lubricants, mineral oils, elastomers, plastics, adhesives, inks, waxes, polyols and selected food, cosmetic and pharmaceutical formulations. These uses do not establish that every commercial grade is suitable for every market. Industrial, food-compliant and pharmacopoeial materials can share the same chemical identity while differing in impurity controls, manufacturing documentation, particle form and release requirements.
Successful use requires attention to dissolution, distribution, antioxidant depletion and the actual oxidation mechanism. BHT cannot reverse established oxidation or replace suitable packaging, contamination control or storage conditions. In regulated applications, the permitted product category and concentration are as important as the chemical name. Current regulatory reviews must also be distinguished from adopted restrictions and from the hazard classification used for occupational handling.

PRODUCT IDENTITY

Product designation: Butylated Hydroxytoluene (BHT)
Chemical name: 2,6-Di-tert-butyl-4-methylphenol
CAS Number: 128-37-0
EC Number: 204-881-4
Molecular Formula: C15H24O
Molecular Weight: Approximately 220.35-220.36 g/mol, depending on the atomic-weight convention used
Chemical family: Sterically hindered alkylphenol; primary phenolic antioxidant
Food-additive designation: E 321 or INS 321, where the applicable food-additive framework permits its use
Cosmetic ingredient designation: BHT in the corrected European cosmetic entry
Physical form: White crystalline solid under ordinary ambient conditions
Butylated Hydroxytoluene (BHT) is a defined substance, rather than a generic mixture of all possible butylated phenols. The molecular formula and molecular weight apply to the BHT molecule. They do not describe a solution, an antioxidant blend, a carrier-containing powder or a formulated preparation sold under a BHT-related designation.
BHT must be distinguished from butylated hydroxyanisole, tertiary-butylhydroquinone, hydroquinone monomethyl ether and other phenolic antioxidants. These materials differ in structure, solubility, performance and permitted uses. A shared antioxidant function does not make them interchangeable in a validated formulation or regulatory dossier.

SYNONYMS

Butylated Hydroxytoluene, BHT, Butylhydroxytoluene, Butylated Hydroxytoluol, Dibutylhydroxytoluene, Dibutylated Hydroxytoluene, 2,6-Di-tert-butyl-4-methylphenol, 2,6-Di-tert-butyl-p-cresol, 2,6-Di-t-butyl-p-cresol, 2,6-Di-t-butyl-4-methylphenol, 2,6-Ditertiarybutyl-p-cresol, 4-Methyl-2,6-di-tert-butylphenol, 4-Methyl-2,6-di-t-butylphenol, 2,6-Bis(tert-butyl)-4-methylphenol, 2,6-Bis(1,1-dimethylethyl)-4-methylphenol, 3,5-Di-tert-butyl-4-hydroxytoluene, 4-Hydroxy-3,5-di-tert-butyltoluene, 1-Hydroxy-4-methyl-2,6-di-tert-butylbenzene, Di-tert-butyl-p-cresol, Di-tert-butyl-p-methylphenol, DBPC, DBMP, Antioxidant DBPC, Antioxidant BHT, E 321, E321, INS 321, Butylated Hydroxytoluene CAS 128-37-0, BHT Phenolic Antioxidant, Hindered Phenolic Antioxidant BHT
The list combines chemical synonyms, abbreviations, additive identifiers and descriptive search terms. An additive identifier does not establish that a particular batch meets food requirements, and the descriptive terms are not separate official chemical identities.

CHEMICAL STRUCTURE AND ANTIOXIDANT MECHANISM

Butylated Hydroxytoluene (BHT) contains a phenolic hydroxyl group, two tert-butyl substituents adjacent to that group and a methyl substituent opposite it on the aromatic ring. The bulky tert-butyl groups provide steric hindrance around the phenolic functionality. The structure combines radical-trapping capability with strong preference for organic rather than aqueous environments.
Oxidation of an organic substrate often proceeds through a chain involving carbon-centered radicals and peroxyl radicals. A carbon-centered radical can react with oxygen to form a peroxyl radical, which can remove hydrogen from another substrate molecule. That step produces a hydroperoxide and a new radical, allowing the process to continue.

BHT can donate its phenolic hydrogen to a suitable radical and form a resonance-stabilized phenoxyl radical. In a simplified chain-breaking representation, a substrate peroxyl radical reacts with the antioxidant to form a hydroperoxide and the antioxidant-derived radical. The latter is less effective at sustaining the same oxidation chain than the original substrate radical.
This mechanism explains why BHT is classed as a primary antioxidant. It also explains a limitation: trapping radicals does not necessarily remove hydroperoxides already present. A secondary antioxidant or other stabilizing component may be useful when hydroperoxide decomposition is important to the system, provided compatibility and regulatory requirements are satisfied.

Butylated Hydroxytoluene (BHT) is consumed or transformed during protection. The residual concentration therefore changes with exposure to oxygen, heat, light and catalytic impurities. A formulation containing the correct initial amount may still lose protection during severe processing or extended service.
Antioxidant efficiency depends on where oxidation occurs and where BHT resides. Strong oil solubility does not guarantee optimum protection at an oil-water interface or inside every polymer phase. Solubility, diffusion, partitioning and the rate of radical generation need to be considered alongside the nominal dose.
The antioxidant mechanism should not be confused with microbial preservation. BHT is selected primarily to limit chemical oxidation; it is not a general replacement for a validated antimicrobial preservative system. Similarly, an antioxidant result from an isolated chemical assay does not establish suitability as a nutritional supplement or therapeutic agent.

PHYSICAL PROPERTIES

Butylated Hydroxytoluene (BHT) is normally a white crystalline or flaked solid with little odor or a faint characteristic aromatic odor. The following values are representative identification data. A commercial specification may use different test methods or tighter acceptance limits, and those requirements should be stated separately.
Molecular formula: C15H24O.
Molecular weight: Approximately 220.35-220.36 g/mol.
Melting behavior: Typically near 69-71 °C; a recognized food-additive identification range is 69-72 °C.
Normal boiling point: Approximately 265 °C in commonly used technical data.
Solid density: Approximately 1.03-1.05 g/cm3 near ambient temperature; bulk powder density is different.
Flash point: Representative reported value approximately 127 °C; the test method must accompany any engineering use of this number.
Water solubility: Very low, generally below 1 mg/L near ambient temperature in commonly cited datasets.
Organic solubility: Soluble in many oils and suitable organic solvents, including ethanol and acetone; capacity depends on temperature and solvent composition.
Partition behavior: Strongly lipophilic, with representative log Kow values around 5.
Vapor pressure: Low at ambient temperature, but volatility and losses can become relevant during heating and extended service.
Melting and solidification
The melting range is useful for identity and quality screening. A depressed or unusually broad range can indicate impurities, but the result must be interpreted using the method and the material's thermal history. A solidification-point requirement is not identical to a capillary melting-range requirement.
Molten BHT allows pumping and metering, but equipment must maintain suitable temperature without overheating. Cooling below the operating window can cause crystallization in transfer lines or valves. A liquid commercial preparation at room temperature may instead contain a solvent or carrier and should not be assumed to be neat molten BHT.
Density and powder handling
Solid density describes the material itself; loose and tapped bulk density describe a particulate bed containing air. The distinction affects hopper sizing, bag volume and volumetric feeding. A change from flakes to powder can alter feeding behavior even when chemical assay remains unchanged.
Particle size influences dust formation and dissolution rate. Fine material may dissolve more quickly but create greater airborne dust during charging, while coarse crystals may require longer mixing. The correct form depends on how BHT enters the process and how dissolution is verified.
Solubility and temperature
Butylated Hydroxytoluene (BHT) is poorly suited to direct addition as an aqueous solution. In an emulsion, it is commonly introduced through a compatible oil phase or a suitable preparation. A clear warm premix should be checked after cooling because solubility can decrease at the final storage temperature.
Strong solubility in one oil does not establish the same capacity in every lubricant, fragrance or cosmetic vehicle. Solvent polarity, dissolved additives and the final water content can change the result. Solubility testing should use the complete formulation at its expected temperature extremes.
Volatility and analytical interpretation
BHT has low ambient vapor pressure, yet small losses can matter when the intended concentration is low. Heating, vacuum processing and a large exposed surface can increase loss. Residual BHT analysis is often more informative than assuming that every added gram remains in the finished product.
pH and viscosity
A conventional aqueous pH is not a meaningful intrinsic specification for neat solid BHT. If an extract or formulated preparation has a reported pH, the extraction conditions or product composition should be identified. Viscosity is relevant to molten BHT and solutions, not to the solid powder as if it were an ambient liquid.

FUNCTION AND PERFORMANCE LIMITS

Butylated Hydroxytoluene (BHT) helps preserve the chemical and physical characteristics of oxidation-sensitive materials. Depending on the substrate, useful outcomes can include delayed rancid odor, reduced color development, more stable viscosity, improved retention of flexibility or a longer oxidation-induction period. Each claim requires a test that reflects the intended application.
BHT is preventive rather than restorative. Adding it after substantial oxidation has occurred does not remove existing carbonyl compounds, deposits or off-odors. A damaged oil or polymer can also contain hydroperoxides that continue to decompose and generate new radicals despite fresh antioxidant addition.
Performance can improve when BHT is paired with a complementary stabilizer, but synergy is formulation-specific. Possible partners include suitable secondary antioxidants, metal-control components or other radical-trapping antioxidants. A useful laboratory combination still requires checks for precipitation, color, processing effects and permitted use.

The relatively low molecular weight supports mobility and dissolution in many organic systems. It can also make BHT more susceptible than larger antioxidants to volatilization, migration or extraction under certain conditions. Long-term high-temperature applications may therefore require a different antioxidant or a broader stabilization package.
Commercial descriptions sometimes call BHT non-staining. This normally refers to its behavior relative to strongly staining antioxidant classes and should not be interpreted as a guarantee against all yellowing. Phenolic oxidation products, reactive gases, other additives and the substrate itself can still affect color.

APPLICATIONS

Lubricating oils

Butylated Hydroxytoluene (BHT) can inhibit oxidation in mineral-oil and selected synthetic-lubricant systems. Oxidation can increase acidity, change viscosity and generate deposits, so antioxidant protection helps maintain useful oil properties. The result depends on base-stock chemistry, temperature, aeration and metal exposure.
Lubricant formulation should compare BHT alone with the intended additive package rather than with an untreated oil only. Other antioxidants, antiwear agents and metal deactivators can influence performance. Evaluate oxidation stability, sludge tendency, color and remaining antioxidant after representative aging.

Hydraulic and circulating oils

BHT can be used in selected hydraulic and circulating oils where oxidation control supports cleanliness and predictable fluid behavior. It functions as an antioxidant rather than as an antiwear additive or viscosity-index improver. The base oil and the operating environment determine how much antioxidant reserve is needed.
Cold stability, filtration and additive compatibility remain important. A dissolved antioxidant that crystallizes at a low operating temperature may be removed by filtration or accumulate in the system. Qualification should therefore include low-temperature clarity and relevant filterability checks.

Electrical insulating oils

Butylated Hydroxytoluene (BHT), also known as DBPC, is used as an oxidation inhibitor in certain electrical insulating oils. Its role is to delay oxidative changes that can affect acidity, sludge formation and oil serviceability. The insulating-oil specification and equipment requirements govern its use.
Electrical performance cannot be inferred from antioxidant assay alone. Water, ionic contamination, dielectric properties and oil condition require their own controls. Re-inhibition of service oil should follow the applicable technical procedure and include an assessment of the oil's existing deterioration.

Greases and oil-containing preparations

BHT can be incorporated into selected grease and oil-based industrial formulations to protect the organic phase. The thickener, base oil and other additives influence distribution and effectiveness. An antioxidant well suited to a liquid oil may behave differently in a structured grease.
Assess storage stability and service performance using the actual grease rather than relying on a premix result. Bleeding, consistency, oxidation and color should be considered together. BHT should not be described as a substitute for mechanical, corrosion or extreme-pressure performance additives.

Fuels and fuel-related materials

In suitable fuel applications, BHT can help limit oxidative deterioration and related formation of gums or insoluble products. The intended fuel specification determines whether BHT is an acceptable antioxidant and at what concentration. Not every fuel, aviation system or jurisdiction uses the same approved additive list.
Qualification should include the actual fuel composition and storage conditions. Antioxidant depletion, trace metals and other additives can influence stability. BHT is not a universal fuel conditioner and should not be assumed to correct contamination or restore off-specification fuel.

Natural and synthetic rubber

Butylated Hydroxytoluene (BHT) can protect selected elastomers from oxidative aging during handling and use. This helps retain properties that oxidation can otherwise change, including flexibility and mechanical strength. Its comparatively low staining tendency can be useful for light-colored rubber compounds.
Rubber protection must consider the complete aging environment. BHT is not automatically an adequate antiozonant, and it does not replace a suitable cure system. Evaluate tensile properties, elongation, color and surface appearance after the relevant heat and oxygen exposure.

Latex and rubber dispersions

BHT can protect oxidation-sensitive polymer phases in selected latices and dispersions. Distribution is important because the solid antioxidant must reach the phase requiring protection. A compatible dispersion or premix may be more effective than direct addition of coarse crystals.
Check colloidal stability after incorporation. Surfactants, carrier solvents and particle size can affect latex behavior independently of BHT's antioxidant chemistry. Coagulum, foaming and changes in viscosity should be examined before a preparation is accepted for production.

Thermoplastics and polymer compounds

Butylated Hydroxytoluene (BHT) can be used in selected plastics and polymer compounds to reduce oxidative damage. Relevant changes can include discoloration, chain scission, loss of mechanical properties or uncontrolled viscosity change. The required protection depends on polymer chemistry and thermal history.
Processing temperature and residence time are critical because BHT can be lost or consumed. A more persistent antioxidant system may be preferable for demanding melt processing or long hot service. Test the actual extrusion or molding history rather than selecting solely from room-temperature solubility.

Masterbatches and additive concentrates

BHT can be delivered through a compatible masterbatch or concentrate when that improves metering and distribution. The carrier must release the antioxidant into the target material without causing unacceptable processing or property changes. A concentrate's total weight is not its active BHT content.
Confirm concentration, dispersion and compatibility at the intended let-down ratio. The carrier can affect food-contact status, odor, color and migration even when the BHT itself meets a defined specification. Traceability should cover both the antioxidant and the formulated concentrate.

Polyether polyols and polyurethane raw materials

Butylated Hydroxytoluene (BHT) can protect selected polyether polyols and related oxidation-sensitive polyurethane raw materials during storage and processing. Oxidation control can help maintain raw-material color and stability before reaction. The antioxidant package should match the polyol and the intended polyurethane process.
Foam or elastomer development should also assess cure behavior, emissions and discoloration. BHT can contribute to phenolic yellowing in some exposure environments, so a low initial color does not guarantee a low final color. Modern low-emission or low-yellowing specifications may require alternative systems.

Adhesives and sealants

BHT can be incorporated into oxidation-sensitive adhesive and sealant formulations, including selected hot-melt systems. It can help protect polymer and tackifier components during manufacture and storage. The useful effect is preservation of the formulation rather than provision of adhesion or cure functionality.
Heat exposure can consume antioxidant, while residual BHT may influence a radical cure. Check viscosity stability, color, bond strength and any intended reaction under the full processing cycle. A formulation using free-radical initiation needs deliberate assessment of antioxidant-induced inhibition.

Coatings, printing inks and resin preparations

Butylated Hydroxytoluene (BHT) can help control unwanted oxidation in selected coating, ink and resin systems. It may be useful for preserving color or limiting degradation of sensitive components. Compatibility with the binder, solvent and drying mechanism is essential.
Oxidatively drying coatings require particular care because an antioxidant can also retard the desired film-forming reaction. Similarly, BHT can affect radical-curing inks and coatings. Its use should be based on storage stability and cured-film results together, rather than assuming that more oxidation inhibition always improves the product.

Waxes and hydrocarbon preparations

BHT can delay oxidative deterioration in waxes and selected hydrocarbon-based preparations. These systems may otherwise develop odor or color during storage and heating. The antioxidant needs to dissolve or disperse uniformly before the material solidifies.
Cooling can concentrate BHT unevenly or produce visible crystals if the formulation is near its solubility limit. Evaluate appearance, storage stability and antioxidant distribution in the finished wax. Any food-contact or personal-care use also depends on the complete material's regulatory qualification.

Cosmetic oils, emulsions and skin-care formulations

Butylated Hydroxytoluene (BHT) can protect oxidation-sensitive oils and other ingredients in cosmetic formulations. This can support odor and color stability when oxidation is a limiting factor. BHT is generally introduced into a compatible phase, with the incorporation procedure chosen to ensure complete distribution.
The European cosmetic entry has category-specific concentration limits, and the appropriate limit applies to the ready-for-use preparation. A maximum permitted concentration is not a recommended starting dose. Formulators should use a justified effective level and assess the complete cosmetic product for safety, stability and labeling.

Oral-care formulations

BHT can be used as an antioxidant in qualifying oral-care formulations, with distinct European limits for mouthwash and toothpaste. The difference between these categories is substantial and must not be replaced by the general limit for other cosmetics. Concentration calculations should include BHT introduced through raw-material blends.
Practical checks include clarity, flavor compatibility, packaging interaction and stability throughout shelf life. Because BHT is poorly water-soluble, a mouthwash needs a suitable formulation approach rather than direct dissolution of crystals in water. Any carrier or solubilizer has its own requirements.

Fragrance and flavor preparations

BHT can protect oxidation-sensitive fragrance or flavor components in appropriate preparations. The desired benefit can include slower development of off-notes or color. Compatibility depends on the specific mixture, since a useful antioxidant in one fragrance oil may precipitate in another.
The finished use determines the regulatory framework. A fragrance used in a cosmetic, a household product and a food flavor cannot all rely on the same authorization. Where the preparation enters a regulated final product, its BHT contribution must be included in the total concentration calculation.

Food fats, oils and specified foods

Food-compliant Butylated Hydroxytoluene (BHT) can help delay oxidative rancidity in permitted fats, oils and specified food applications. The effective location and concentration depend on the food matrix, processing and packaging. Early incorporation into a suitable fresh material is generally more useful than addition after substantial oxidation.
Permission is category- and jurisdiction-specific. Limits may apply to total antioxidant, the fat or oil fraction, the finished food or a specific ingredient such as gum base. These bases are different and must be checked before a concentration is calculated or a label is prepared.

Food-contact plastics, coatings and adhesives

BHT can stabilize certain materials used in food packaging, including qualifying polymers, coatings and adhesives. Here the intended antioxidant function belongs to the packaging material, while migration into food must remain within the applicable requirements. Food-additive use and food-contact use are separate compliance questions.
Qualification should consider the exact polymer, BHT concentration, contact temperature, food type and duration. A compliant antioxidant raw material does not automatically make every finished package compliant. Supplier documentation, formulation review and testing need to address the actual article.

Pharmaceutical excipient applications

Butylated Hydroxytoluene (BHT) can serve as an antioxidant excipient in selected pharmaceutical formulations when the grade and route of administration are suitable. Compendial compliance and impurity control are particularly important in this market. The role is stabilization of the formulation rather than an assumed therapeutic effect.
Pharmaceutical qualification requires the applicable monograph, supplier controls and compatibility with the active substance and packaging. A high assay alone does not establish that an industrial BHT lot is acceptable. Product-specific development must demonstrate stability without creating unacceptable degradation products or changing drug performance.

Feed and specialist agricultural formulations

BHT can protect oxidation-sensitive ingredients in qualifying feed or agricultural preparations where its use is authorized. In feed, antioxidant requirements can involve combinations with other antioxidants and limits specific to the intended framework. In a crop-protection formulation, BHT may be a stabilizing component rather than the active substance.
These markets require their own current authorization and composition assessment. Human-food conditions should not be copied into feed or agricultural specifications. The physical form, carrier and antioxidant concentration of a commercial preparation also affect metering and compatibility.

Solvent stabilization and laboratory chemistry

Butylated Hydroxytoluene (BHT) is used to stabilize selected solvents and reactive organic materials against unwanted radical chemistry. Its presence can be important during storage but can also interfere with a planned reaction or analytical measurement. The required inhibitor concentration belongs to the exact material and stability system.
BHT does not make a peroxide-forming solvent permanently safe. Inhibitor depletion, evaporation and storage history still matter, and distillation may separate the stabilizer from the solvent. Testing and handling should follow the solvent's validated procedure; antioxidant addition is not a remedy for an already hazardous peroxide condition.

FORMULATION GUIDANCE

Start by identifying the deterioration mechanism. If the main problem is microbial growth, hydrolysis, metal corrosion or light-induced change unrelated to radical oxidation, BHT may not address it. An effective antioxidant study begins with a measurable oxidation-related endpoint in the actual material.
Select the grade against the intended market before optimizing dose. Food, cosmetic, pharmaceutical and technical applications have different documentation needs. A trial that performs well with an unsuitable grade does not establish an acceptable commercial formulation.
Prepare a compatible premix when direct solid addition would leave undissolved particles. Use the lowest practical incorporation temperature and sufficient mixing to achieve a verified uniform concentration. Excess heating can increase loss and expose the substrate to unnecessary oxidation.
Check the finished formulation after cooling and temperature cycling. A hot clear mixture may become supersaturated and deposit BHT crystals later. Include realistic storage temperatures, packaging and dilution steps when defining the test.

Calculate active BHT rather than the weight of a carrier-containing preparation. For example, adding 0.10% of a preparation containing 20% BHT contributes 0.020% active BHT before accounting for BHT from other ingredients. This calculation illustrates mass balance, not a recommended dosage or a regulatory limit.
Include every source of BHT in the formulation total. Antioxidant can arrive through oils, fragrances, polymers or premixes as well as through a direct addition. This matters particularly when a finished-product concentration limit is low.
Run a dose-response study within the permitted range and use conditions representative of processing and service. Measure oxidation indicators, color, odor and relevant physical properties. The best level is the justified effective concentration, not automatically the highest concentration that remains soluble or legally permitted.

Compare BHT with a complementary stabilization package when multiple mechanisms contribute to deterioration. Check whether a metal-control component, secondary antioxidant or packaging improvement provides more benefit than further BHT. Any combined system should be evaluated for precipitation, discoloration and cure effects.
Retain analytical samples from the initial blend and after aging. Residual BHT, peroxide-related measurements and substrate degradation markers can help distinguish poor distribution from depletion or an unsuitable mechanism. Shelf-life claims should be based on that combined evidence rather than on the initial recipe alone.

PRODUCTION AND COMMERCIAL GRADES

Butylated Hydroxytoluene (BHT) is commonly manufactured through controlled alkylation of p-cresol with an appropriate tert-butylating feedstock. The desired substitution pattern places tert-butyl groups on both positions adjacent to the phenolic hydroxyl group. Purification and crystallization help establish the required identity, purity and physical form.
Process-derived impurities can include related alkylphenols, residual starting material and other organic components. Their importance depends on the application and specification. A high overall assay does not automatically demonstrate that every relevant impurity is below the required limit.
Technical grades are selected for industrial stabilization where their specification meets the process need. Food-compliant grades require the appropriate food-additive purity and supply documentation. Pharmacopoeial grades must meet the relevant current monograph and associated quality expectations. These descriptions should be supported by documentation for the actual material.
Powder, granules, flakes and molten BHT can have the same underlying chemical identity while differing in handling and metering. A solution or supported preparation additionally introduces a carrier. Active content, solvent identity and any anti-caking component should therefore be confirmed before comparing prices, dosage or performance.

QUALITY CONTROL

Identity
Use a suitable identification method, such as infrared spectroscopy supported by chromatography where appropriate. The result should confirm BHT rather than a related phenolic antioxidant. CAS Number, product label and analytical identity should be consistent throughout receipt and release.

Assay
Gas chromatography is a recognized approach for BHT assay, while other validated methods may be appropriate for particular grades or formulated products. State whether the result is on an as-is or another defined basis. A reference-standard purity value should not be applied to a commercial preparation without checking composition.

Related substances
Control relevant phenolic and process-related impurities using the required method and acceptance limits. A normalized chromatographic area result may not adequately describe every impurity of interest. Methods should resolve the components that matter to the specification and intended market.

Melting and solidification behavior
Melting range and solidification point provide useful quality indicators but are different measurements. A broad or depressed transition can suggest contamination or compositional variation. Use the designated method rather than comparing an incoming capillary result directly with an unrelated solidification specification.

Recognized food-additive benchmarks
A recognized food-additive monograph specifies assay of at least 99.0%, an identification melting range of 69-72 °C and a solidification point not below 69.2 °C. It also specifies sulfated ash not above 0.005%, lead not above 2 mg/kg and phenolic impurities not above 0.5%. These are monograph-specific criteria, not an automatic certification of any BHT batch or a substitute for current jurisdictional requirements.

Color, odor and appearance
Inspect the physical form for unusual discoloration, foreign matter or unexpected odor. For color-sensitive formulations, a defined solution-color test can be more informative than visual inspection of the solid alone. Any solution preparation must use consistent concentration and solvent conditions.

Moisture and volatile matter
Use the moisture or loss-on-drying method required by the grade. These measurements are not necessarily interchangeable because a drying loss can include substances other than water. Sampling and conditioning should not create an apparent difference between otherwise comparable batches.

Inorganic residues and elemental impurities
Ash-related and elemental-impurity controls are important where the end use demands them. Apply the actual monograph or agreed specification and a method with suitable sensitivity. A broad statement that a material is high purity is not a replacement for the required elemental results.

Particle size and flow
Particle-size distribution, bulk density and flow behavior can be relevant to automated feeding and premix preparation. Changes in physical form can affect dosing accuracy without changing chemical purity. Establish appropriate physical acceptance criteria when the process depends on consistent charging behavior.

Functional performance
An oxidation-stability comparison in a qualified reference substrate can supplement chemical analysis for sensitive applications. The test should distinguish the antioxidant's contribution from variations in the substrate. Record concentration, temperature, oxygen exposure and endpoint so results remain comparable.

Batch documentation
Maintain the certificate, batch number, specification version, manufacturing or release information and relevant storage conditions. Where a monograph or market-specific claim is needed, confirm it for the actual grade. The certificate should support the agreed requirements rather than merely repeat the product name.

COMPATIBILITY AND PROCESSING

Butylated Hydroxytoluene (BHT) should be compatible both with the bulk formulation and with the phase undergoing oxidation. Poor distribution can leave part of the substrate unprotected even when total assay appears correct. Sampling at several locations may be needed to demonstrate uniformity after a new incorporation procedure.
BHT can inhibit desired radical reactions as well as unwanted oxidation. In free-radical polymerization, UV curing or peroxide-initiated processes, the antioxidant load may change induction time or conversion. Evaluate the total BHT introduced through all raw materials before changing initiator or cure conditions.
Avoid incompatible reactive substances during storage and transfer. Strong oxidizers can react with organic phenols, while strong bases and other aggressive reagents may alter BHT chemistry. Compatibility with containers, seals and equipment should be established for the actual temperature and any carrier solvent present.

Heat only as required for validated dissolution or molten handling. The boiling point is not an acceptable routine processing target, and antioxidant stability does not imply unlimited thermal endurance. Heated equipment needs suitable temperature control, ventilation and protection against localized overheating.
When BHT is used in a mixture, the mixture's hazards depend on every component. A flammable solvent can dominate the fire classification of a dilute BHT solution. Likewise, an aqueous preparation can have different spill behavior from neat crystals, so the solid-substance SDS should not be substituted for the formulated product's SDS.

EU CLASSIFICATION AND REGULATORY ASSESSMENT

Regulatory review date: 15 October 2026. Available documentation commonly identifies BHT with supplier classifications for aquatic hazards, particularly Aquatic Acute 1, H400, and Aquatic Chronic 1, H410. These mean very toxic to aquatic life and very toxic to aquatic life with long-lasting effects, respectively. They should not be presented as an established harmonized Annex VI entry merely because they appear in many safety data sheets.
This review did not establish a current mandatory EU harmonized classification entry for BHT. Accordingly, no invented Annex VI index number is assigned here. Use the supplied material's current SDS for classification, label elements and any applicable multiplication factors. A harmonized classification and a supplier self-classification are different regulatory bases.
Public European assessment information identifies BHT, also called 2,6-di-tert-butyl-p-cresol, as under endocrine-disruptor assessment through substance evaluation. An assessment under development is not the same as a final determination that the substance meets a legal endocrine-disruptor criterion. 

Nor does it independently establish inclusion on an authorization list or a general prohibition.
The fact that a cosmetic safety assessment considered endocrine-related concerns does not settle every environmental or industrial regulatory question. Different assessments address different exposure routes, endpoints and legal frameworks. Conclusions should be applied within their stated scope.
Regulatory monitoring should distinguish an information request, an assessment, a proposal, an adopted measure and its legally applicable date. A future classification or restriction must not be anticipated as current law. Equally, an older favorable assessment should not be described as a guarantee that regulatory conditions cannot change.

COSMETIC REGULATORY CONDITIONS

Under the European cosmetic restriction introduced by Regulation (EU) 2022/2195, the category-specific maximum concentrations for BHT in ready-for-use preparations are 0.001% for mouthwash, 0.1% for toothpaste and 0.8% for other leave-on and rinse-off products. These correspond to 10, 1,000 and 8,000 mg/kg, respectively, when the percentage is expressed by mass.
The cosmetic entry is Annex III reference number 325. A corrigendum published on 6 November 2025 identifies the ingredient name as BHT and includes the chemical names 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol. The name correction should not be mistaken for a new chemical identity or a change to the listed concentration limits.
The original restriction set transition dates of 1 July 2023 for placing noncompliant products on the Union market and 1 January 2024 for making them available. Those transition dates have passed by the review date of this profile. Product development should therefore use the applicable restricted conditions rather than the pre-restriction position.
These concentrations are ceilings, not default formulation levels. The complete product still needs a safety assessment, correct ingredient declaration and suitable stability evidence. BHT introduced through fragrances, oils or other preparations should be included when assessing the total concentration.

FOOD AND FOOD-CONTACT REGULATORY CONDITIONS

In the European food-additive framework, BHT is identified as E 321. Its use depends on authorized categories, applicable limits and purity requirements under the relevant food-additive legislation. The additive number is not permission to add BHT to every food or to use an industrial grade in a food application.
The purity framework under Regulation (EU) No 231/2012 and the authorization framework under Regulation (EC) No 1333/2008 serve different purposes. Meeting a purity specification does not by itself establish that a proposed food use is permitted. The category, concentration basis, combined-antioxidant provisions and any carry-over conditions must be checked.

In the United States, 21 CFR 182.3173 addresses BHT antioxidant use with a condition that total antioxidant content does not exceed 0.02% of the food's fat or oil content, including essential oil content, subject to good manufacturing practice. That basis must not be rewritten as a universal 0.02% limit on the total finished-food mass.
Separate provisions address specified foods. Under 21 CFR 172.115, BHT must have at least 99% assay, and the table specifies limits for total BHA and BHT in the listed applications. Examples include 50 mg/kg for dry breakfast cereals and 10 mg/kg for potato granules. These are category-specific examples, not a general treatment rate for all foods.
For food-contact materials, the relevant authorization can depend on the polymer, coating, adhesive or other article and the conditions of contact. A direct-food permission cannot simply be transferred to packaging, and a packaging authorization cannot be treated as direct-food authorization. Migration and extractables obligations belong to the actual finished article and use.

A United States post-market assessment of BHT uses in human food and food-contact materials was accompanied by a request for information published on 13 May 2026. The public comment period was subsequently reopened with a deadline of 31 August 2026. The available review status is information assessment; these notices are not themselves a final withdrawal of existing authorizations.
Commercial qualification should check current legal conditions for the destination market, including any more specific subnational requirements. This profile does not replace a category-specific compliance review or declare that every existing application remains acceptable under every local rule.

PHARMACEUTICAL AND OTHER GRADE REQUIREMENTS

Butylated Hydroxytoluene (BHT) is available in grades intended to meet pharmacopoeial requirements, but the unqualified product name does not establish such compliance. Confirm the relevant current monograph, test results and supply documentation for the exact grade. Manufacturing and change-control expectations also form part of a pharmaceutical qualification.
The presence of an excipient monograph does not authorize every route, concentration or finished medicinal product. Compatibility with the active ingredient, degradation profile, packaging and intended patient exposure must be assessed in the formulation. A reference standard and a production excipient are also different supply categories.
Feed, crop-protection, drinking-water-contact and other specialist uses have distinct regulatory conditions. A successful antioxidant result does not establish authorization for those applications. Select the grade and documentation against the specific market rather than extrapolating from food or cosmetic status.

SAFETY AND HANDLING

Handle Butylated Hydroxytoluene (BHT) with measures that minimize dust generation and unnecessary contact. Local extraction can be useful at bag opening, weighing and charging points. Closed or controlled addition can improve both worker exposure and dosing consistency.
Select eye protection, gloves and work clothing using the current SDS and the actual task. Molten BHT presents an additional thermal-burn hazard, and hot-transfer work needs suitable splash protection. A dilute solution may require different glove or ventilation choices because its solvent contributes additional hazards.

Use respiratory protection within an appropriate workplace program when engineering controls do not adequately control exposure. Particle size and the charging method influence dust exposure, while heated systems can create vapor or condensate exposure. Apply current local exposure requirements rather than assuming one numerical limit is valid everywhere.
Control accumulation and dispersion of organic dust. Evaluate whether the handled physical form can create a combustible-dust hazard under site conditions, and base equipment protection on relevant material data. The absence of a flammable-liquid classification for the ambient solid does not establish that dust or molten material cannot burn.

Keep BHT separate from strong oxidizers and other incompatible reactive chemicals. Avoid contaminating food, cosmetic or pharmaceutical grades with technical process materials. Good housekeeping also helps prevent an environmentally harmful spill from being spread through routine cleaning or traffic.
Food or cosmetic use under specified conditions does not make the concentrated raw material harmless. Occupational handling and consumer-product exposure are different situations. Likewise, an industrial hazard classification does not by itself answer whether a finished regulated product is acceptable at its permitted concentration.

FIRST AID

Eye contact
Rinse promptly with clean water, keeping the eyelids open and removing contact lenses if easy to do. Continue rinsing and obtain medical attention if irritation persists or the exposure is significant. Hot material requires prompt assessment for thermal injury as well as chemical exposure.

Skin contact
Wash the affected area thoroughly with soap and water and remove contaminated clothing. Do not use solvents to clean the skin. For contact with molten BHT, cool the affected area with water and obtain urgent medical assistance; do not forcibly remove material adhering to injured skin.

Inhalation
Move the affected person to fresh air without exposing rescuers to a hazardous atmosphere. Seek medical advice for persistent coughing, respiratory discomfort or other symptoms. Emergency assistance should be provided by trained personnel using appropriate protection.

Ingestion
Rinse the mouth and obtain advice from a poison service or medical professional. Do not induce vomiting unless specifically directed. Never give anything by mouth to an unconscious person, and provide the exact product information to the treating professional.

STORAGE

Store Butylated Hydroxytoluene (BHT) in well-closed packaging in a cool, dry, suitably ventilated area. Protect the material from excessive heat, contamination and prolonged unnecessary exposure to light and air. Use the grade-specific storage conditions and retest or shelf-life information.
Prevent moisture ingress and physical damage to bags, liners or containers. Although BHT is not water-soluble, wet packaging or repeated temperature changes can affect powder handling and introduce contamination. Keep food and pharmaceutical grades under the segregation and traceability conditions required for their use.
For molten BHT, control the operating temperature and ensure that lines, valves and vessels are designed for the service. Avoid localized overheating and unintended solidification in a blocked transfer path. Heated systems require a separate operating procedure from storage of ambient solid material.
Storage of a BHT solution must account for the carrier's flash point, volatility and compatibility. The solubility of BHT at the minimum expected temperature should also be established. A crystallized concentrate cannot be assumed to have uniform active content without an appropriate reconditioning and mixing procedure.
No universal shelf life applies to all grades and packaging forms. Retest decisions should consider the specification, appearance, assay, impurity profile and storage history. A visually white powder alone does not establish continued compliance with a demanding end-use specification.

SPILL MANAGEMENT AND FIRE RESPONSE

Restrict access to a spill and avoid generating airborne dust. Trained personnel should collect stable solid material using a method suited to the site and physical form, placing it in appropriate labeled containers. Prevent entry into drains, soil and surface waters.
Do not wash a BHT spill into the drainage system. Poor water solubility does not remove its aquatic hazard, and contaminated washwater still requires management. Recovered material should not be returned to clean stock without a defined assessment and release procedure.
For molten material, protect responders from hot surfaces and splashes and allow recovery only under the appropriate procedure. For a solution spill, assess the solvent as well as BHT. Ignition control and ventilation can be essential even when the pure antioxidant is an ambient solid.
Suitable extinguishing media can include water spray, foam, dry chemical or carbon dioxide according to the fire and supplied SDS. Burning organic material can produce hazardous combustion gases. Firefighters need protective equipment and breathing apparatus, and contaminated firefighting water should be contained where feasible.
Waste BHT, contaminated absorbents and empty packaging must follow the applicable waste requirements. Avoid mixing residues with strong oxidizer waste or treating an antioxidant-containing formulation as nonhazardous solely because its BHT concentration is low.

TRANSPORT AND ENVIRONMENTAL CONSIDERATIONS

Neat solid BHT is commonly shipped under UN 3077, ENVIRONMENTALLY HAZARDOUS SUBSTANCE, SOLID, N.O.S., Class 9, Packing Group III, when the applicable transport criteria are met. The technical name, environmental marking and any marine-pollutant requirements must follow the current SDS and modal rules.
Some small-package provisions can change the transport obligations for qualifying consignments. Their applicability depends on package quantity, packaging and the transport mode; they do not mean that BHT loses its environmental hazard. A molten grade or solvent-containing preparation requires its own assessment.
BHT's low water solubility and lipophilic character influence its environmental distribution. Released material can associate with organic matter rather than remain uniformly dissolved. This behavior does not justify disposal to soil or water, and environmental acceptability cannot be inferred from solubility alone.
Consider antioxidant release through dust, contaminated water, extraction and migration from finished materials. The release pathway and concentration determine the relevant assessment. Neither biodegradation potential nor successful use in a polymer establishes a general environmentally harmless claim.

COMMON FORMULATION PROBLEMS

Undissolved particles after addition
Check solvent capacity, particle form, temperature and mixing time. Use a compatible premix if appropriate, and verify dissolution at the final process temperature rather than judging only a heated sample.

Crystals appear after cooling
The formulation may be near or above its low-temperature solubility limit. Reassess concentration and carrier choice and include temperature cycling. Heating until clear is not a permanent solution unless the finished material remains stable under its defined storage conditions.

Antioxidant assay varies between samples
Investigate incomplete mixing, crystallization, segregation and analytical sampling. For a concentrate, confirm that the carrier and active fraction remain uniform. A correct batch-average addition cannot compensate for poor local distribution.

Oxidation continues despite BHT addition
Check whether the substrate was already oxidized, whether BHT reached the relevant phase and whether catalytic contamination is present. Measure residual antioxidant and oxidation markers before deciding that a higher concentration is appropriate.

Antioxidant disappears during processing
Review temperature, residence time, vacuum exposure, air contact and reaction with the substrate. Distinguish volatilization from chemical consumption using suitable analysis. A more persistent stabilizer system may be needed for demanding conditions.

Polymerization or curing slows
Account for all BHT carried into the formulation through raw materials. Radical scavenging can interfere with a desired radical process. Adjust the validated formulation or cure strategy rather than treating the effect as an unrelated equipment problem.

Yellowing develops during storage
Investigate phenolic oxidation, exposure to reactive gases, substrate alkalinity and interactions with other additives or packaging. The description non-staining does not exclude every color pathway. Compare the complete material with and without BHT under the actual exposure conditions.

Water-based formulation separates or becomes cloudy
Check BHT solubilization and its distribution between phases. A compatible oil-phase addition or qualified preparation may help, but any new solubilizer can affect stability and regulatory status. Evaluate the final formulation after dilution and cooling.

Food-use calculation exceeds a limit
Confirm whether the applicable limit is based on fat, oil, finished food or another specified component. Include other antioxidants where the rule uses a combined total. A percentage copied from a different category can produce a substantial calculation error.

Cosmetic product assigned the wrong concentration ceiling
Identify the exact product category. European mouthwash, toothpaste and other cosmetic preparations have different BHT ceilings. Include BHT from premixes and apply the limit to the ready-for-use product.

Technical material proposed for pharmaceutical use
Check the current monograph, impurity profile, manufacturing controls and supplier qualification. Chemical identity and high assay are necessary but do not independently demonstrate suitability for a medicinal product.

Peroxide-forming solvent considered safe because it contains BHT
Review storage history, inhibitor condition and the solvent's required testing program. BHT can delay some radical chemistry but does not neutralize an established hazardous peroxide condition. Follow the solvent-specific assessment procedure.

Regulatory review described as an immediate ban
Check the legal status and dates of the measure. An information request or assessment does not itself withdraw an authorization. Future decisions should be monitored without presenting an assumed outcome as current law.

FREQUENTLY ASKED QUESTIONS

What is Butylated Hydroxytoluene (BHT)?
Butylated Hydroxytoluene (BHT) is a hindered phenolic antioxidant used to slow oxidative deterioration in suitable organic materials.

What is the CAS Number of BHT?
The CAS Number is 128-37-0.

What is the EC Number?
The EC Number is 204-881-4.

What are its molecular formula and molecular weight?
The formula is C15H24O and the molecular weight is approximately 220.35-220.36 g/mol.

What is the chemical name of BHT?
The chemical name is 2,6-di-tert-butyl-4-methylphenol, also known as 2,6-di-tert-butyl-p-cresol.

Is BHT the same as BHA?
No. Butylated hydroxyanisole is a different antioxidant with a different chemical identity and regulatory conditions.

What does BHT look like?
Neat BHT is normally a white crystalline solid supplied as powder, granules or flakes.

Can BHT be supplied as a liquid?
Yes. It can be supplied molten or in a formulated solution; the form and carrier must be identified.

What is the melting point?
BHT typically melts near 69-71 °C, while a recognized food-additive identification range is 69-72 °C.

Is BHT soluble in water?
BHT has very low water solubility and should not be treated as a water-soluble antioxidant.

How does BHT work?
It transfers phenolic hydrogen to suitable radicals and helps interrupt radical oxidation chains.

Does BHT reverse rancidity?
No. It can delay further oxidation but does not remove existing oxidation products or restore damaged material.

Is BHT an antimicrobial preservative?
Its principal formulation role is antioxidant protection, and it does not replace a validated microbial-preservation system.

Where is BHT used industrially?
Applications include suitable oils, lubricants, polymers, rubber, polyols, adhesives, inks and waxes.

Does BHT always prevent yellowing?
No. Although often described as non-staining, BHT-containing systems can develop color under particular exposure and formulation conditions.

Can BHT interfere with curing?
Yes. Its radical-scavenging action can delay desired free-radical polymerization or curing.

Why can BHT crystallize in a formulation?
The concentration can exceed its solubility at the storage temperature, or changes in the solvent mixture can reduce solubility.

Is there one recommended concentration for every application?
No. The effective and permitted level depends on the substrate, process, product category and jurisdiction.

What is E 321?
E 321 is the European food-additive designation for BHT where its use is authorized.

Does the E 321 designation make every BHT grade food-compliant?
No. The exact grade must meet the applicable purity and documentation requirements, and the food use must be permitted.

Does the United States 0.02% condition always refer to finished food?
No. Under 21 CFR 182.3173 the condition is based on the food's fat or oil content and concerns total antioxidant content.

What are the European cosmetic concentration limits?
The listed maxima are 0.001% in mouthwash, 0.1% in toothpaste and 0.8% in other leave-on and rinse-off preparations.

What ingredient name appears in the corrected European cosmetic entry?
The corrected entry uses BHT as the ingredient name and retains the same CAS Number.

Should BHT from fragrances and premixes be counted?
Yes. Its contribution should be included when determining total BHT in a formulation.

Is industrial BHT automatically pharmaceutical grade?
No. The exact grade requires appropriate monograph compliance and pharmaceutical qualification.

Are H400 and H410 automatically EU harmonized classifications for BHT?
No. Frequently used supplier classifications should not be presented as an established harmonized entry without the relevant legal basis.

Does endocrine-disruptor assessment mean BHT is already legally identified as an endocrine disruptor?
An assessment under development does not itself establish a final legal determination or a general prohibition.

Did the 2026 United States information request itself ban BHT?
No. It initiated information collection for post-market assessment and was not a final withdrawal of authorization.

What transport classification is commonly used for solid BHT?
UN 3077, environmentally hazardous substance, solid, n.o.s., Class 9, Packing Group III is commonly used, subject to the applicable rules.

Where can grade-specific technical information be obtained?
Contact Ataman Chemicals for the applicable specification, TDS, SDS, COA and commercial supply information.

FINAL TECHNICAL SUMMARY

Butylated Hydroxytoluene (BHT), CAS Number 128-37-0 and EC Number 204-881-4, is a defined hindered phenolic antioxidant with formula C15H24O. Its central function is to interrupt radical oxidation chains in suitable organic materials. The two tert-butyl groups and phenolic structure support a useful balance of antioxidant activity, oil affinity and compatibility across a wide range of formulations.

BHT can delay changes in odor, color, viscosity and mechanical properties when oxidation is the relevant deterioration mechanism. Applications range from lubricants and insulating oils to rubber, plastics, adhesives, polyols and selected regulated formulations. Performance depends on distribution, solubility, thermal history, antioxidant consumption and the condition of the substrate before addition.
Commercial selection should distinguish neat solid, molten material and carrier-containing preparations, and should match the grade to the destination market. Assay, related substances, melting or solidification behavior, color, moisture, elemental impurities and physical form can all influence suitability. Application testing and residual-antioxidant measurement complement the raw-material certificate.

Regulated uses require precise interpretation of product category and concentration basis. European cosmetic limits differ for mouthwash, toothpaste and other preparations, while food and food-contact requirements follow separate frameworks. The 2026 United States post-market assessment is an ongoing review process rather than an automatic cancellation of existing permissions. European endocrine-related assessment activity should likewise be distinguished from a final legal determination.
Environmental protection, dust control and appropriate hot-material handling remain relevant despite BHT's familiar applications. Common supplier aquatic classifications require careful spill containment and waste management. Safe and consistent use combines suitable grade selection, controlled incorporation, validated storage and documentation for the actual formulation.

For Butylated Hydroxytoluene (BHT) technical specifications, TDS, SDS, COA and commercial supply, contact Ataman Chemicals. The chosen grade should match the required purity, physical form, processing conditions and intended application.

Ataman Chemicals
Phone: +90 216 577 10 10
Email: info@atamankimya.com