 |
Synonyms:PEGDMA PEG dimethacrylate PEG bismethacrylate Methacrylate-PEG-Methacrylate PEG hydrogel Molecular Formula:(C2H4O)nC8H10O3 Molecular Weight: 200400600 HS Code: 3906909090 Grade: Industrial grade99% Hazard Class:General Cargo | |||||||||
128-37-0
bosschem
128-37-0
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, and its EU food additive code is E321. 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 and organic solvents. It protects oils, rubber, and plastics from oxidative deterioration by capturing free radicals with its phenolic hydroxyl groups and breaking oxidation chain reactions—this is the fundamental reason why it serves as a classic antioxidant in the fuel, lubricant, rubber, and plastics industries.
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.
Physically , 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 oil-soluble substance; its melting point is approximately 70°C and its boiling point is approximately 265°C. When heated, it melts into a colorless to pale yellow transparent liquid, which can evaporate with water vapor. It has low volatility and good stability at room temperature, making it easy to store and transport.
Chemically , BHT is a hindered phenolic antioxidant: the hydrogen atom on its phenolic hydroxyl group is easily captured by free radicals (hydrogen donation), transforming the active free radical into a stable product, thereby terminating the oxidation chain reaction; after hydrogen donation, 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 polymer processing and high-temperature oil processing, but it is photosensitive and will gradually change color after prolonged storage or exposure to light.
Why does BHT play these roles in industries such as petroleum fuels, lubricants, rubber, and plastics? Its mechanism of action mainly includes the following:
Phenolic hydroxyl group hydrogen donation chain breaking mechanism : The oxidation of oils and polymers are both free radical chain reactions. The phenolic hydroxyl group of BHT provides hydrogen atoms to the peroxide free radical in the reaction, deactivating it into hydroperoxide. 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 molecules 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.
Oil-soluble distribution mechanism : BHT is highly soluble in hydrocarbon oils, organic solvents 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. This is the basis for its ability to uniformly protect fuels, lubricants and plastic products.
Synergistic antioxidant mechanism : When BHT is compounded with auxiliary antioxidants such as phosphites and thioesters and metal passivators, the main and auxiliary antioxidants can regenerate in succession, and the metal passivators can also chelate trace metal ions catalytically oxidized. The compound system can significantly extend the service life of oils and polymers, and can achieve the same protection at a lower dosage.
Heat-resistant processing stabilization mechanism : BHT has a melting point of about 70℃ and a boiling point of about 265℃. It is not easily decomposed and volatilized under high-temperature conditions in plastic processing, rubber vulcanization and oil processing. It can be completely retained in the product and continue to play an antioxidant role throughout the entire cycle from production, storage to use.
II. All Uses of BHT
1. Petroleum and fuel industry
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 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 oxidation chain reactions. In the industrial field, it is known as Antioxidant 264 and Anti-aging Agent 264, playing a crucial role as an "antioxidant guardian" in various applications, from gasoline and diesel fuel to engine oils and transformer oils, from tire rubber to wire and cable plastics, and from candle crayons to hot melt adhesives and coatings. It achieves significantly extended service life for oils, rubber, and polymer materials with low-level addition. Understanding its hindered phenolic structure explains its versatility and widespread application across major industrial sectors, including petroleum, lubricants, rubber, plastics, and fine chemicals—the fundamental reason why it, despite sharing a similar origin with food-grade E321, can thrive in factory workshops.
