Industrial grade98% Food Grade99% Butylated Hydroxytoluene CAS 128-37-0

What is BHT? How does it work?

BHT, short for Butylated hydroxytoluene, is a synthetic phenolic compound with the chemical name 2,6-di-tert-butyl-4-methylphenol. Its CAS number is 128-37-0. In the industrial field, it is often referred to as antioxidant 264 or anti-aging agent 264. It is a white crystalline powder, almost insoluble in water but highly soluble in oils, greases, and organic solvents. It protects oily products and materials from deterioration by capturing free radicals with its phenolic hydroxyl groups and breaking oxidation chain reactions—this is its core ability to protect not only potato chips and chewing gum on the table but also engine oil and tire rubber.

Basic information : Chinese name: Butylated hydroxytoluene (also known as dibutylhydroxytoluene, antioxidant 264, anti-aging agent 264); English name: Butylated hydroxytoluene (abbreviation BHT); CAS number: 128-37-0; Molecular formula: C15H24O; Molecular weight: 220.35; Melting point: approximately 70℃; Boiling point: approximately 265℃; Other names: BHT, 2,6-di-tert-butyl-4-methylphenol, E321, etc.

Structurally , BHT's full chemical name is 2,6-di-tert-butyl-4-methylphenol: a phenolic hydroxyl group (-OH) is attached to position 1 of the benzene ring, a tert-butyl group (-C(CH3)3) is attached to positions 2 and 6, and a methyl group (-CH3) is attached to position 4. The two large tert-butyl groups on either side of the phenolic hydroxyl group form significant steric hindrance, keeping the phenolic hydroxyl group in a "protected" state. This "hindered phenol" structure is the core structural feature that distinguishes BHT from ordinary phenolic compounds, and it also determines that the free radical it generates after donating hydrogen is exceptionally stable.

physical properties , BHT is a white crystalline or crystalline powder with a faint, distinctive odor; it is almost insoluble in water but readily soluble in ethanol, ether, acetone, benzene, and organic media such as animal and vegetable oils and mineral oils, making it a typical fat-soluble substance; its melting point is about 70°C and its boiling point is about 265°C. When heated, it melts into a colorless to pale yellow transparent liquid and can evaporate with water vapor.

Chemically , BHT is a hindered phenolic antioxidant: the hydrogen atom on its phenolic hydroxyl group is easily captured by free radicals (donating hydrogen), transforming the active free radical into a stable product, thereby terminating the chain reaction of oil oxidation; after donating hydrogen, BHT itself transforms into a phenoxy radical, which is difficult to initiate a new oxidation reaction due to the steric hindrance of the two tert-butyl groups, thus its antioxidant effect is long-lasting; BHT is chemically stable and heat-resistant, and can be used in high-temperature processing such as frying and baking, but it is sensitive to light and will gradually change color after prolonged storage or exposure to light.

Why does BHT play these roles in various fields such as food, cosmetics, pharmaceuticals, feed, and industry? Its mechanism of action mainly includes the following:

Phenolic hydroxyl group hydrogen donation chain scission mechanism : The oxidation of oils, fats and polymers is a chain reaction of free radicals. The phenolic hydroxyl group of BHT provides hydrogen atoms to the peroxide free radicals in the reaction, deactivating them into hydroperoxides. The free radical chain is thus broken, and the oxidation rate decreases significantly. This is the fundamental action of all the antioxidant effects of BHT.

Hindered phenol radical passivation mechanism : After hydrogen donation, BHT becomes a phenoxy radical. Two large tert-butyl groups surround the radical center like a shield, making it difficult for it to react with oil or polymer molecules. Therefore, BHT does not produce "secondary catalysis" like ordinary phenols, and can maintain protection for a long time with a single hydrogen donation.

Lipid-soluble partitioning mechanism : BHT is almost insoluble in water but highly soluble in oils, fats and polymer melts. After addition, it can dissolve uniformly and reside in the oil phase or resin matrix, directly intercepting free radicals inside the system, unlike water-soluble antioxidants which are confined to the aqueous phase. Therefore, it can protect vegetable oils and oily cosmetics, as well as fuels, lubricants and plastic products.

Synergistic antioxidant mechanism : When BHT is combined with food antioxidants such as BHA, propyl gallate, and citric acid, or with industrial auxiliary antioxidants such as phosphites, thioesters, and metal passivators, the main and auxiliary components can work together to regenerate and chelate trace metal ions. The combined effect is stronger than that of single addition, and the same protection can be achieved at a lower dosage.

Heat-resistant and long-lasting protection mechanism : BHT has a melting point of about 70°C and a boiling point of about 265°C. It is not easily decomposed and volatilized in high-temperature processes such as frying, baking, plastic processing and rubber vulcanization. It can be retained in the finished product and continue to play a role during the storage and use period, covering the entire cycle from processing to shelf.

All Uses of BHT

1. Food processing sector

Fats and fried foods (vegetable oils, shortening, margarine)

When added directly to oils, it blocks the oxidation chain reaction and delays the formation of rancidity and off-flavors; fried foods continuously absorb oil during frying, and BHT protects both the frying oil and the finished product.

Corresponding products: vegetable oil, shortening, margarine, potato chips, fried snacks, etc.

Cereals and baked goods (oatmeal, biscuits, nuts, mooncakes)

It protects the unsaturated fats in grain germ and nuts, prevents nuts from developing a stale or oily taste, and maintains the crisp texture of baked goods.

Corresponding products: breakfast cereals, cookies, biscuits, nuts, mooncakes, etc.

chewing gum and candy

It stabilizes the oil components in the flavoring, prevents the flavoring from oxidizing and losing its flavor, and maintains the consistent flavor of chewing gum over a long period of time.

Corresponding products: chewing gum, bubble gum, hard candy, soft candy, etc.

Instant noodles and fast food noodle products

It protects the oil in fried dough cakes and prevents oxidation during storage, which can produce unpleasant odors.

Corresponding products: instant noodles, instant rice vermicelli, instant rice noodles, etc.

Cured meat products and sausages

It slows down the oxidation of fat in meat products, inhibits darkening of color and deterioration of flavor, and extends shelf life when combined with packaging processes.

Corresponding products: sausages, cured meat, dried meat, pickled meat, etc.

Edible flavorings and fragrances

To prevent the easily oxidized components of aldehydes and ketones in the fragrance from deteriorating, and to maintain the freshness of the aroma and batch consistency.

Corresponding products: food flavorings, essential oils, food seasonings, etc.

2. Cosmetics and Personal Care

Lipstick and lip gloss

It protects the oils, waxes and pigments in the formula from oxidation, preventing the lipstick from discoloring, changing flavor, and separating from the surface.

Corresponding products: lipsticks, lip balms, lip glosses, etc.

Skin cream and lotion

It prevents the plant oils and esters in the moisturizing cream from becoming rancid, stabilizes the texture of the cream, and extends its shelf life after opening.

Corresponding products: moisturizing cream, lotion, face cream, body lotion, sunscreen, etc.

Makeup products

It protects the oil and wax components of oil-based makeup products such as eyeshadow and foundation, preventing clumping and discoloration.

Corresponding products: eyeshadow, foundation, concealer, blush, etc.

toiletries

It stabilizes the oils and fragrances in soaps, shampoos, and shower gels, preventing discoloration and off-flavors caused by oxidation.

Corresponding products: soap, shampoo, shower gel, etc.

Essential oils and aroma products

It prevents the oxidation and polymerization of terpenes in essential oils and aromatherapy oils from causing aroma distortion and increased viscosity, thus maintaining a long-lasting fragrance.

Corresponding products: essential oils, aromatherapy oils, scented candles, etc.

3. Health Supplements Industry

Dietary supplements

It protects easily oxidized nutrients such as fish oil and unsaturated fatty acids, preventing a decline in their potency.

Corresponding products: fish oil soft capsules, compound nutritional supplements, etc.

4. Feed and Animal Nutrition

Compound feed and premix

It protects the fat, vitamins and other nutrients in the feed from oxidation, and prevents the feed from heating up, spoiling and losing palatability.

Corresponding products: compound feed, premixed feed, concentrated feed, etc.

Pet food

Protect the oils and nutrients in pet food, and maintain its flavor and freshness.

Corresponding products: dry pet food, pet snacks, wet pet food, etc.

5. Industrial Applications

Gasoline and diesel fuel

To prevent fuel from oxidizing and forming gum and sediment during storage and use, keep the fuel clean, and avoid clogging of nozzles and filters.

Corresponding products: automotive gasoline, diesel, biofuels, etc.

fuel oil and heavy oil

It delays the oxidation and deterioration of marine fuel oil and industrial heavy oil during storage.

Corresponding products: marine fuel oil, industrial heavy oil, etc.

Engine oil and industrial lubricants

It slows down the oxidation of base oil, prevents the acid value from increasing, the viscosity from increasing and the sludge from depositing, and extends the service life of the oil and the oil change cycle.

Corresponding products: engine oil, gear oil, hydraulic oil, compressor oil, etc.

Transformer oil and electrical oil

To prevent the insulating oil from oxidizing and aging, and to maintain dielectric properties and equipment safety.

Corresponding products: transformer oil, switch oil, cable oil, etc.

grease

It protects the base oil and thickener in the grease from oxidation and keeps the grease stable.

Corresponding products: general-purpose lithium-based grease, industrial lubricating grease, etc.

Tires and rubber products

As an antioxidant, it delays the thermo-oxidative aging of rubber, prevents cracking, hardening and discoloration, and extends the service life of products.

Corresponding products: tires, conveyor belts, hoses, seals, etc.

Synthetic rubber and latex

Storage stabilizers for synthetic rubbers such as styrene-butadiene rubber, cis-butadiene rubber, and isoprene rubber, as well as their latexes, to prevent oxidative cross-linking of raw rubber during storage.

Corresponding products: raw synthetic rubber, latex products, rubber shoes, etc.

Polyolefin resins (PP, PE)

It is a primary antioxidant used in the processing and use of polypropylene and polyethylene, inhibiting thermo-oxidative degradation and discoloration, and maintaining mechanical properties.

Corresponding products: polypropylene, polyethylene, films, injection molded parts, etc.

Engineering plastics and modified materials

Heat-stabilizing components used in the processing and use of resins such as ABS, polyoxymethylene, and polyamide.

Corresponding products: ABS products, polyoxymethylene gears, modified plastic particles, etc.

Wires and cables and electronic and electrical materials

The antioxidant system components of cable insulation and sheathing materials delay thermal and oxygen aging and ensure electrical safety.

Corresponding products: wire and cable materials, appliance casings, electrical insulation components, etc.

Paraffin and Candles

To prevent paraffin wax from oxidizing and turning yellow, producing an odor, and to maintain the appearance and burning performance of the candle.

Corresponding products: candles, craft candles, etc.

Crayons and wax-based stationery

It stabilizes the color and hardness of the wax, preventing discoloration during writing and storage.

Corresponding products: crayons, wax-based pigments, etc.

Hot melt adhesives and pressure-sensitive adhesives

To prevent the colloid from oxidizing and becoming sticky or discolored during melt processing and storage, and to maintain its adhesive properties.

Corresponding products: hot melt adhesive, pressure-sensitive tape, label adhesive, etc.

Coatings and inks

Protects coating resins and oil components, preventing skinning and thickening during storage.

Corresponding products: coatings, printing inks, topcoat varnishes, etc.

Unsaturated polyester resin

It inhibits oxidation and gelation of unsaturated polyester resin during storage, thus extending its shelf life.

Corresponding products: unsaturated polyester resin, fiberglass raw materials, etc.

Chemical intermediates and fine chemicals

To prevent organic intermediates and fine chemical raw materials from oxidizing, discoloring, and deteriorating during storage and transportation.

Corresponding products: organic intermediates, fine chemical raw materials, etc.

III . Summary

BHT (Butylhydroxytoluene, CAS 128-37-0) is a hindered phenolic lipid-soluble antioxidant with the chemical name 2,6-di-tert-butyl-4-methylphenol. Its single phenolic hydroxyl group and two sterically hindered tert-butyl groups allow it to efficiently capture free radicals while simultaneously passivating its own free radicals, thus effectively blocking oxidative chain reactions. It serves as food additive E321, protecting vegetable oils, potato chips, chewing gum, and moisturizers, and as antioxidant 264 and anti-aging agent 264, protecting gasoline, diesel, engine oils, tire rubber, and wire and cable plastics – a dual-purpose product from the kitchen table to the factory floor. Understanding its hindered phenolic structure explains why it can simultaneously act as a core antioxidant in numerous fields such as food, cosmetics, animal feed, and industry – this is the fundamental reason why BHT spans both the consumer and industrial worlds.