Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. Autoxidation leads to degradation of organic compounds, including living matter. Antioxidants are frequently added to industrial products, such as polymers, fuels, and lubricants, to extend their usable lifetimes. Foods are also treated with antioxidants to forestall spoilage, in particular the rancidification of oils and fats. In cells, antioxidants such as glutathione, mycothiol, or bacillithiol, and enzyme systems like superoxide dismutase, can prevent damage from oxidative stress.
Butylated hydroxytoluene (BHT), also known as dibutylhydroxytoluene, is a lipophilic organic compound, chemically a derivative of phenol, that is useful for its antioxidant properties. BHT is widely used to prevent free radical-mediated oxidation in fluids and other materials, and the regulations overseen by the U.S. F.D.A.—which considers BHT to be "generally recognized as safe"—allow small amounts to be added to foods. Despite this, and the earlier determination by the National Cancer Institute that BHT was noncarcinogenic in an animal model, societal concerns over its broad use have been expressed. BHT has also been postulated as an antiviral drug, but as of December 2022, use of BHT as a drug is not supported by the scientific literature and it has not been approved by any drug regulatory agency for use as an antiviral.
Phenol formaldehyde resins (PF) are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde. Used as the basis for Bakelite, PFs were the first commercial synthetic resins. They have been widely used for the production of molded products including billiard balls, laboratory countertops, and as coatings and adhesives. They were at one time the primary material used for the production of circuit boards but have been largely replaced with epoxy resins and fiberglass cloth, as with fire-resistant FR-4 circuit board materials.
A plasticizer is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture.
Isobutylene is a hydrocarbon with the chemical formula (CH3)2C=CH2. It is a four-carbon branched alkene (olefin), one of the four isomers of butylene. It is a colorless flammable gas, and is of considerable industrial value.
In industrial chemistry, a stabilizer or stabiliser is a chemical that is used to prevent degradation. Above all, heat and light stabilizers are added to plastic and rubber materials because they ensure safe processing and protect products against aging and weathering. In particular polyvinyl chloride would not be possible without stabilizers.
Photodegradation is the alteration of materials by light. Commonly, the term is used loosely to refer to the combined action of sunlight and air, which cause oxidation and hydrolysis. Often photodegradation is intentionally avoided, since it destroys paintings and other artifacts. It is, however, partly responsible for remineralization of biomass and is used intentionally in some disinfection technologies. Photodegradation does not apply to how materials may be aged or degraded via infrared light or heat, but does include degradation in all of the ultraviolet light wavebands.
Polyester is a category of polymers that contain one or two ester linkages in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include naturally occurring chemicals, such as in plants and insects, as well as synthetics such as polybutyrate. Natural polyesters and a few synthetic ones are biodegradable, but most synthetic polyesters are not. Synthetic polyesters are used extensively in clothing.
2,6-Di-tert-butylphenol is an organic compound with the structural formula 2,6-((CH3)3C)2C6H3OH. This colorless solid alkylated phenol and its derivatives are used industrially as UV stabilizers and antioxidants for hydrocarbon-based products ranging from petrochemicals to plastics. Illustrative of its usefulness, it prevents gumming in aviation fuels.
The Dakin oxidation (or Dakin reaction) is an organic redox reaction in which an ortho- or para-hydroxylated phenyl aldehyde (2-hydroxybenzaldehyde or 4-hydroxybenzaldehyde) or ketone reacts with hydrogen peroxide (H2O2) in base to form a benzenediol and a carboxylate. Overall, the carbonyl group is oxidised, whereas the H2O2 is reduced.
Polymer stabilizers are chemical additives which may be added to polymeric materials to inhibit or retard their degradation. Mainly they protect plastic and rubber products against heat, oxidation, and UV light. The biggest quantity of stabilizers is used for polyvinyl chloride (PVC), as the production and processing of this type of plastic would not be possible without stablizing chemicals. Common polymer degradation processes include oxidation, UV-damage, thermal degradation, ozonolysis, combinations thereof such as photo-oxidation, as well as reactions with catalyst residues, dyes, or impurities. All of these degrade the polymer at a chemical level, via chain scission, uncontrolled recombination and cross-linking, which adversely affects many key properties such as strength, malleability, appearance and colour.
Triisopropylamine is an organic chemical compound consisting of three isopropyl groups bound to a central nitrogen atom. As a hindered tertiary amine, it can be used as a non-nucleophilic base and as a stabilizer for polymers; however, its applications are limited by its relatively high cost and difficult synthesis.
tert-Butyl bromide (also referred to as 2-bromo-2-methylpropane) is an organic compound with the formula Me3CBr (Me = methyl). The molecule features a tert-butyl group attached to a bromide substituent. This organobromine compound is used as a standard reagent in synthetic organic chemistry. It is a colorless liquid.
2,4,6-Tri-tert-butylphenol (2,4,6-TTBP) is a phenol symmetrically substituted with three tert-butyl groups and thus strongly sterically hindered. 2,4,6-TTBP is a readily oxidizable aromatic compound and a weak acid. It oxidizes to give the deep-blue 2,4,6-tri-tert-butylphenoxy radical. 2,4,6-TTBP is related to 2,6-di-tert-butylphenol, which is widely used as an antioxidant in industrial applications. These compounds are colorless solids.
Tris(2,4-di-tert-butylphenyl)phosphite is an organophosphorus compound with the formula [(C4H9)2C6H3O]3P. This white solid is a widely used stabilizer in polymers where it functions as a secondary antioxidant. It also reduces discoloration (yellowing) of plastics. The compound is a phosphite ester formed by the reaction of 2,4-di-tert-butylphenol with phosphorous trichloride. It is an approved food contact materials in the US.
Pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate) is a chemical compound composed of four sterically hindered phenols linked through a pentaerythritol core. It is used as primary antioxidant for stabilizing polymers, particularly polyethylene and polypropylene.
Di-tert-butylcyclopentadiene is an organic compound with the formula (Me3C)2C5H4, where Me = methyl. It is a colorless liquid that is soluble in organic solvents. The compound is the conjugate acid of the di-tert-butylcyclopentadienyl ligand, (Me3C)2C5H3− (sometimes abbreviated Cp‡−). Two regioisomers of di-tert-butylcyclopentadiene exist, depending on the relative location of the double bonds.
Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is a hindered phenolic antioxidant commonly used as a polymer stabiliser.
2,4-Di-tert-butylphenol (2,4-DTBP) is a white solid with a phenolic odour. It is primarily used as a raw material for the production of several commercially important antioxidants and phenolic benzotriazole-type UV absorbers. It also finds use as a starting material in the synthesis of agrochemicals, fragrances and catalysts.
Tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate is a chemical compound used as a polymer stabilizer in plastics. Like other hindered phenols it acts as a primary antioxidant. More than 1000 tonnes per year are used in the EU.
