OCTABENZONE

Octabenzone is an oil-soluble hydroxybenzophenone UV absorber designed to intercept damaging ultraviolet radiation before it initiates polymer photo-oxidation.
Its unusually long linear octyloxy group gives the molecule strong affinity for polyolefins, plasticisers, hydrocarbon media and organic coating binders.
Commercial selection therefore centres on optical purity, resin compatibility, migration control and the physical form needed for clean, uniform addition.

CHEMICAL IDENTITY AND COMMON NAMES

Octabenzone is the established name for 2-hydroxy-4-(octyloxy)benzophenone, also recognised in ingredient nomenclature as Benzophenone-12.
The structure contains a benzophenone chromophore, an ortho phenolic hydroxyl group and a linear n-octyloxy substituent.
The n-octyl chain is part of the defined identity and distinguishes Octabenzone from related hydroxybenzophenones carrying methoxy, hydroxy or other alkoxy groups.

Names using octoxy and octyloxy describe the same oxygen-linked C8 chain in this context.
Industrial designations such as UV-531 and BP-12 are widely used for Octabenzone, while proprietary product names are separate from the chemical identity.

Synonyms and Common Names: Octabenzone, Octabenzon, Benzophenone-12, Benzophenone 12, BP-12, UV-531, UV 531, HOBP, OH-OBP, 2-hydroxy-4-(octyloxy)benzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-(n-octyloxy)benzophenone, 2-hydroxy-4-(octoxy)benzophenone, 2-hydroxy-4-(n-octoxy)benzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 4-(octyloxy)-2-hydroxybenzophenone, 4-(n-octyloxy)-2-hydroxybenzophenone, 4-n-octyloxy-2-hydroxybenzophenone, 4-(octoxy)-2-hydroxybenzophenone, 4-octoxy-2-hydroxybenzophenone, 2-benzoyl-5-(octyloxy)phenol, 2-benzoyl-5-octyloxyphenol, 2-hydroxy-4-(octyloxy)phenylmethanone, [2-hydroxy-4-(octyloxy)phenyl]phenylmethanone, methanone, [2-hydroxy-4-(octyloxy)phenyl]phenyl-, methanone, (2-hydroxy-4-(octyloxy)phenyl)phenyl-, benzophenone, 2-hydroxy-4-(octyloxy)-, benzophenone, 2-hydroxy-4-octoxy-

TECHNICAL IDENTIFICATION

CAS Number: 1843-05-6
EC / EINECS Number: 217-421-2
Molecular Formula: C21H26O3
Molar Mass: 326.43 g/mol
IUPAC Name: 2-hydroxy-4-(octyloxy)phenylmethanone
Chemical Class: Ortho-hydroxybenzophenone UV absorber
UNII: 73P3618V2E
InChIKey: QUAMTGJKVDWJEQ-UHFFFAOYSA-N
Canonical SMILES: CCCCCCCCOC1=CC(=C(C=C1)C(=O)C2=CC=CC=C2)O

THE UV ENERGY-DISSIPATION CYCLE

The phenolic hydroxyl group lies next to the benzophenone carbonyl and forms a strong intramolecular hydrogen bond with the carbonyl oxygen.
That six-membered chelated arrangement is the functional core of Octabenzone rather than a minor structural detail.

After the chromophore absorbs a UV photon, an ultrafast excited-state intramolecular proton transfer converts the chelated enol form into an excited keto-like form.
The excited species then relaxes mainly through non-radiative internal conversion, releasing the absorbed energy as a very small amount of heat.
Reverse proton transfer regenerates the starting ground-state structure and makes repeated absorption cycles possible.

By intercepting radiation before a polymer chromophore absorbs it, Octabenzone reduces radical initiation, chain scission, oxidation and crosslinking.
The visible consequences are slower yellowing, reduced chalking and cracking, better gloss retention, and longer preservation of tensile and impact properties.
Octabenzone screens radiation rather than repairing oxidation that has already occurred, which is why uniform distribution and early addition are important.

PHYSICAL AND OPTICAL PROFILE

Appearance: Colourless to pale yellow crystalline solid supplied as powder, crystals or flakes
Odour: Essentially odourless
Melting Point: 47–49 °C for purified material and commonly 47–51 °C as a commercial release range
Thermal Behaviour: Decomposes above approximately 300 °C
Density: Approximately 1.16 g/cm3
Flash Point: Approximately 102 °C, closed cup
Vapour Pressure: Approximately 3.38 × 10-8 mmHg at 20 °C
Water Solubility: Below 0.001 mg/L at 20 °C and pH 6
Representative Solubility at 25 °C: About 74 g/100 g acetone, 40 g/100 g n-hexane, 2 g/100 g methanol and 2.6 g/100 g 95% ethanol
Organic-Solvent Behaviour: Soluble in aromatic hydrocarbons, ketones and many ester solvents, with much lower solubility in short-chain alcohols
Octanol/Water Partition Coefficient: log Kow approximately 6.8–7.4
UV Absorption Region: Approximately 270–380 nm in representative coating media
Principal Absorption Maxima: Approximately 291 nm and 328 nm under representative measurement conditions
Volatility: Extremely low at ambient temperature

The melting point sits close enough to normal processing temperatures for Octabenzone to soften and distribute readily during polymer compounding.
The same low melting range makes heat exposure during storage relevant because warm powder can consolidate, form lumps or lose free-flowing behaviour without undergoing chemical decomposition.

Strong absorption in the UV-B region and into the lower UV-A region provides useful protection for many organic matrices while leaving most visible light comparatively unaffected.
Colour and visible-light transmittance nevertheless matter in clear, white and pastel products, where a small amount of initial colour is more noticeable than in dark or highly pigmented systems.

WHY THE OCTYL CHAIN CHANGES FORMULATION BEHAVIOUR

The linear C8 chain shifts Octabenzone decisively toward non-polar phases.
It improves dissolution in hydrocarbons, plasticisers and hydrophobic binders and supports compatibility with polyethylene, polypropylene and ethylene-based copolymers.

High lipophilicity and negligible water solubility also mean that Octabenzone cannot simply be stirred into waterborne formulations as a molecular solution.
Waterborne coatings, inks and dispersions need prior dissolution in an appropriate organic phase, an emulsified delivery system or a controlled fine-particle dispersion.

The octyl group lowers volatility and helps retention during melt processing, but Octabenzone remains a mobile small molecule rather than a polymer-bound stabiliser.
Resin polarity, crystallinity, additive loading, part thickness and service temperature therefore govern migration, extraction and surface blooming.
A compatibility test at the intended loading reveals whether the absorber remains molecularly dispersed after cooling, ageing and contact with adjacent materials.

PRODUCTION AND PURITY ARCHITECTURE

Industrial synthesis commonly begins with 2,4-dihydroxybenzophenone and selectively converts the para hydroxyl group into an n-octyl ether.
Reaction with 1-chlorooctane or 1-bromooctane under basic conditions is an established route, while carbonate-based alkylation provides an alternative process design.

Selectivity is critical because the ortho hydroxyl group must remain free to form the internal hydrogen bond responsible for UV energy dissipation.
Over-alkylation at both hydroxyl groups can raise assay by nonspecific techniques while reducing functional UV performance.
Unreacted 2,4-dihydroxybenzophenone, di-alkylated material, residual octylating agent, octanol, inorganic salts, residual solvent and coloured oxidation products are therefore meaningful process impurities.

Work-up normally combines aqueous washing, phase separation, solvent removal and crystallisation or recrystallisation.
The resulting crystal habit determines whether the product is sold as a fine powder, friable crystalline mass or lower-dust flake.
Controlled cooling and drying help stabilise melting behaviour, colour, particle form and flow.

APPLICATIONS AND INDUSTRIES

Polyolefin films and moulded articles

Octabenzone protects low-density polyethylene, linear low-density polyethylene, high-density polyethylene and polypropylene against sunlight-driven degradation.
Applications include agricultural and greenhouse films, outdoor film and sheet, crates, containers, pipes, storage components and polypropylene fibres.
The absorber is especially useful in thin sections because UV radiation can penetrate a large proportion of the material thickness.

In agricultural film, combination with a hindered amine light stabiliser addresses two different stages of degradation.
Octabenzone reduces the amount of radiation absorbed by the polymer, while the hindered amine system interrupts radical oxidation that still occurs during service.
This complementary mechanism generally provides more durable protection than either additive acting alone.

PVC, styrenics and engineered plastics

Plasticised and rigid polyvinyl chloride use Octabenzone to slow colour change, surface embrittlement and loss of flexibility during light exposure.
Polystyrene, styrenic copolymers, polycarbonate, acrylic polymers, polyesters and selected polyamides can also benefit when the absorber is compatible with the exact resin and processing window.

The low melting point promotes rapid incorporation into a polymer melt, but solubility after cooling remains the decisive issue.
Transparent parts place the strongest demands on absorber colour, clarity and absence of crystals, while pigmented articles require attention to how pigments alter UV penetration and stabiliser demand.

Coatings, inks, adhesives and sealants

Octabenzone is incorporated into alkyd, acrylic, polyurethane, polyester, epoxy and other organic binder systems to improve colour, gloss and film-integrity retention.
The same UV-screening function supports printing inks, pressure-sensitive and structural adhesives, and sealants exposed through a transparent substrate or at an exterior bond line.

Solventborne systems can receive a pre-dissolved concentrate, whereas powder coatings rely on homogeneous dry blending followed by melt distribution.
Clear-coat performance depends on complete dissolution and on adequate protection through the full film thickness.

UV-curable systems require a different formulation decision because Octabenzone can compete with the photoinitiator for lamp output.
Its absorption spectrum, concentration and film thickness are matched with the photoinitiator and irradiation source so that weathering protection does not reduce cure depth or surface conversion.

Elastomers and polyurethane systems

Rubber compounds, thermoplastic elastomers and polyurethane products use Octabenzone where UV exposure would otherwise promote cracking, hardening, discolouration or loss of elasticity.
Compatibility with the elastomer, plasticiser and other compounding ingredients controls both initial dispersion and long-term resistance to blooming.
Flexible articles also require extraction testing when they contact oils, cleaners or skin because those media can mobilise a lipophilic additive.

Packaging and content protection

Packaging films, sheets and containers can use Octabenzone as a UV barrier that protects both the polymer and light-sensitive contents.
This function is relevant to products whose colour, aroma, active content or shelf stability deteriorates under near-UV exposure.

Octabenzone appears on authorised lists for defined plastic food-contact uses in major jurisdictions and is subject to compositional and migration conditions.
Food-contact selection therefore combines identity and purity documentation with overall and specific migration testing for the finished article under its intended time, temperature and food-simulant conditions.

Cosmetics and personal-care formulations

Benzophenone-12 is recognised as a cosmetic UV absorber for protecting a formulation and its ingredients from light-induced deterioration.
The octyloxy group favours incorporation into oil phases, anhydrous products and hydrophobic emollient systems.

The ingredient function of UV absorber is distinct from legal authorisation as an active sunscreen filter intended to protect human skin.
Cosmetic procurement is consequently aligned with the permitted function, product category, concentration and ingredient rules of the destination market.

Pesticide formulations and petroleum wax

Octabenzone can protect photosensitive components in specifically authorised pesticide formulations by screening incident UV radiation.
In the United States, its regulated inert-ingredient use is limited to no more than 0.2% in pesticide formulations applied to growing crops.
That narrow authorisation is a formulation-specific use and not a general approval for unrestricted agricultural addition.

Petroleum wax and related hydrocarbon systems use Octabenzone to reduce light-induced colour and property changes.
Its oil solubility and very low water affinity support distribution through the wax phase without introducing an aqueous component.

Analytical and materials research

Neat analytical standards support purity testing, migration analysis, extractables and leachables work, environmental monitoring and method development for polymer additives.
Materials research also uses Octabenzone to study photostabilisation, additive diffusion, ageing and the interaction between UV absorbers, radical scavengers and antioxidants.

FORMULATION LOGIC AND ADDITIVE COMBINATIONS

A common screening range for many polymer systems is approximately 0.1–0.5% by weight, with the final concentration set by polymer type, article thickness, pigmentation, exposure intensity and service-life target.
Very thin films, demanding outdoor exposure or content-protection duties can require a different stabilisation package from thick, opaque mouldings.

Octabenzone combines effectively with hindered amine light stabilisers because UV screening and radical control are complementary.
Phenolic antioxidants and phosphites address thermal and processing oxidation, producing a package that covers melt history as well as later sunlight exposure.
Additive ratios are balanced to prevent antagonism, excessive colour, plate-out and migration.

For thermoplastics, Octabenzone may enter with the resin, through a preblend or as a masterbatch concentrate.
Its low melting point enables early wetting, while sufficient mixing distributes the molten absorber before the strand or article cools.
Prolonged residence above the necessary processing temperature is avoided to limit colour formation and additive loss.

For liquid coatings and inks, complete dissolution is established before pigments or other components make visual assessment difficult.
A filtration step can remove undissolved crystals or foreign matter when the application demands high optical clarity.
Cooling and accelerated storage tests then reveal recrystallisation that may not be visible immediately after manufacture.

GRADE SELECTION AND COMMERCIAL FORM

Industrial polymer grade is commonly supplied at a minimum assay of 98–99% by gas or liquid chromatography.
Release parameters usually include appearance, melting range, volatile matter, ash, visible-light transmittance and solution clarity.
Low ash protects electrical and optical properties, while low volatile matter supports cleaner extrusion and reduced die deposit.

Coating and ink grades place additional emphasis on colour, UV-visible absorption, solvent clarity and absence of insoluble matter.
Cosmetic and regulated-contact grades require tighter control of odour, residual solvents, elemental impurities, process by-products and the documentation associated with the intended market.

Powder gives rapid dissolution and dispersion but requires stronger dust control.
Flake or coarse crystalline material reduces airborne dust and can improve handling in larger batches.
Masterbatch delivery simplifies metering into thermoplastics but introduces carrier-resin identity and active-content uniformity as additional purchasing parameters.

Analytical grade is selected for method calibration, migration measurement or impurity identification rather than bulk stabilisation.
The useful package includes assigned purity, identity data, traceability, storage conditions and an expiry or retest period.

QUALITY CONTROL AND DOCUMENTATION

Gas chromatography and high-performance liquid chromatography are suitable for assay and related-substance profiling.
Infrared spectroscopy, nuclear magnetic resonance and mass spectrometry confirm the benzophenone structure, linear octyl ether and molecular identity.
Differential scanning calorimetry or a controlled capillary method verifies the narrow melting transition.

UV-visible spectroscopy is a functional identity test as well as an optical-quality tool.
Absorbance maxima, specific absorbance and visible transmittance are measured at a defined concentration, path length and solvent because those conditions directly affect the result.
Colour testing at approximately 450–500 nm helps predict initial tint in clear or lightly coloured matrices.

Moisture, volatile matter, ash, residual solvents and solution clarity complete the routine industrial profile.
Chromatographic control of unreacted 2,4-dihydroxybenzophenone and di-alkylated by-product is particularly valuable because these impurities change polarity, melting behaviour and UV response.

The Certificate of Analysis records the released batch results.
The Technical Data Sheet describes processing characteristics and intended application scope, while the Safety Data Sheet defines classification, exposure controls, transport information and emergency measures.
Food-contact, cosmetic and pesticide-formulation projects add the regulatory declarations and migration or compositional data required for that use.

ENVIRONMENTAL FATE AND RELEASE CONTROL

Octabenzone is highly hydrophobic, essentially insoluble in water and strongly attracted to organic matter and solids.
An estimated organic-carbon sorption coefficient near 64,000 indicates very low mobility through soil in the dissolved phase.
Very low vapour pressure also makes volatilisation from dry material and water a minor transport route.

The compound is not readily biodegradable, with only about 5–6% mineralisation observed over 28 days in a screening test.
Hydrolysis is slow across environmentally relevant pH conditions, while sunlight can contribute to transformation in exposed surface water.
Measured fish bioconcentration factors of approximately 70–190 indicate moderate to high accumulation potential.

Aquatic-effect data occur at very low concentrations, so powder, process water, cleaning solvent and polymer-additive waste are kept out of drains and natural waters.
Environmental control focuses on source containment and collection because dilution is not an appropriate response for a poorly soluble, strongly sorbing substance.

REGULATORY POSITION

Octabenzone is registered for industrial chemical uses in the European Union and is present on the United States chemical inventory.
Its inclusion in an inventory establishes chemical-market status rather than automatic suitability for every finished-product application.

Defined indirect food-contact uses exist in both European and United States frameworks, with migration and compositional conditions applying to the finished material.
The cosmetic designation Benzophenone-12 identifies a UV-absorbing ingredient function but does not by itself establish sunscreen-active status.
The pesticide-formulation use is separately regulated and carries its own concentration and crop-use limitations.

SAFETY AND OCCUPATIONAL CONTROL

Signal Word: Warning
Principal Classified Hazard: H317 and may cause an allergic skin reaction
Combustibility: Combustible organic solid with a closed-cup flash point near 102 °C
Acute Oral Toxicity: Low in available studies, with a rat oral LD50 above 10,000 mg/kg
Environmental Concern: Very toxic effects can occur in aquatic organisms at low concentrations

Low acute oral toxicity does not remove the need for controlled industrial handling.
Repeated skin contact is avoided because sensitisation can lead to allergic reactions after prior exposure.
Fine powder can cause mechanical irritation of the eyes and respiratory tract even though vapour exposure is negligible at ambient temperature.

Contained charging, local exhaust ventilation and dust collection minimise inhalation and cross-contamination.
Chemical-resistant gloves, safety goggles and protective work clothing prevent routine contact.
A suitable particulate respirator is used when powder handling cannot be fully enclosed or ventilated.

Fire can generate carbon monoxide, carbon dioxide and irritating organic fumes.
Water fog, alcohol-resistant foam, dry chemical or carbon dioxide may be selected for the surrounding fire conditions, with contaminated extinguishing water retained for controlled disposal.

FIRST AID

Inhalation: Move the affected person to fresh air and obtain medical attention if coughing, breathing difficulty or irritation continues.
Skin Contact: Remove contaminated clothing and wash the skin thoroughly with soap and water.
Eye Contact: Rinse cautiously with clean water for at least 15 minutes, remove contact lenses when easy to do and obtain medical assessment if irritation persists.
Ingestion: Rinse the mouth, do not induce vomiting and seek medical advice after a significant ingestion or if symptoms occur.
Note to Physicians: Treatment is symptomatic and supportive, with attention to allergic skin response and any exposure to formulation solvents.

HANDLING, STORAGE AND SPILL RESPONSE

Handling takes place away from open flames, hot surfaces and strong oxidising agents.
Powder transfer uses low-drop-height or closed equipment because dust prevention protects both workers and product cleanliness.
Grounded equipment is appropriate where fine organic dust can accumulate or where flammable solvents are present.

Storage uses a tightly closed original or compatible container in a cool, dry and well-ventilated area protected from direct sunlight.
Temperature remains comfortably below the 47–49 °C melting range to preserve free flow and prevent caking.
Opened containers are resealed promptly to exclude dirt and moisture.

Spilled powder is collected without dry sweeping or compressed air.
A filtered industrial vacuum or careful damp collection limits airborne dust, and recovered material is placed in a labelled waste container.
Solvent solutions are absorbed with compatible inert material and kept away from drains, soil and surface water.

PACKAGING AND PROCUREMENT CONSIDERATIONS

Bulk Octabenzone is commonly packed in lined fibre drums or lined multiwall bags that protect the light-coloured solid from contamination and moisture.
Smaller high-purity and analytical quantities are suited to sealed amber or opaque containers with chemically compatible closures.
Pallet protection and temperature-aware storage reduce compaction during warm-weather transport.

A technically complete inquiry identifies the polymer or binder, processing temperature, final application, outdoor exposure, desired service life, additive form and pack size.
Optical applications also state colour and transmittance requirements, while regulated-contact uses identify the destination market and migration-document package.

Important purchasing parameters include assay method, melting range, colour, volatile matter, ash, UV-visible spectrum, solution clarity, particle or flake form, residual solvents and named process impurities.
Projects involving clear films, UV-curable coatings or food-contact articles also define compatibility, cure-response or migration testing at the finished-formulation level.

Ataman Kimya supports Octabenzone inquiries involving polymer and coating grade selection, optical specifications, powder or flake presentation, regulatory documentation, packaging and planned supply volume.
For product-specific assistance, contact Ataman Kimya at +90 216 577 10 10 or info@atamankimya.com.