Alkylaromatic compounds (products of alkylation of benzene, toluene, xylenes etc.) are used as solvents, lubricating oil additives, transformer oil and intermediate for the manufacture of surface active agents and detergents. They are excellent synthetic plasticizers for rubber. Alkylbenzenes can also be used as lubricating greases and lacquer resins.
Alkylated phenols and their derivatives are outstanding antioxidants and stabilizers in lubricating oils, polymers, synthetic fuels and wide variety of oxygen sensitive materials.
2-Alkyl-4-methylphenol upon condensation with formaldehyde readily gives antioxidant of the bisphenol type. 2-Alkyl-4-methylphenol upon further alkylation produces 2,4,6-trialkylated phenol. 2,4- and 2,6-Xylenols also give 2,4,6-trialkylated phenols upon alkylation. These are antioxidants of the monophenol type. These compounds protect polymers, lubricating oils etc. from thermal degradation. The degradation occurs by the radical chain mechanism.
Alkylated phenols and some of their derivatives are effectively used as insecticides, herbicides and bactericides. These are also used as plant growth regulators and antiseptics. Alkylphenols are used as plasticizers for polymeric material, corrosion inhibitors for metals, pour point depressants for transmission fluid. At low temperature fluidity of oil can be increased by alkylphenols.
Alkylphenols also find use in plastic masses and adhesives, in perfume industry, in the manufacture of paints, varnishes and soaps, in dye industry etc. Alkylphenols are intermediates for the manufacture of surfactant and detergents.
Alkylated ortho-, meta- and para- cresols can be utilized as antioxidants and as intermediates in the production of herbicides and surfactant of the non-ionic type. Monoalkylphenols with alkyl groups of 5-8 carbons atoms are strong bactericides while those with longer alkyl groups (up to 8-12 carbon atoms) are valuable intermediates in the synthesis of non-ionic surfactants. Oil soluble thermoplastic resins used in paints, varnishes and adhesive formulations can be produced upon polycondensation of ortho- or para-alkylphenol with formaldehyde. One of the most effective stabilizers is Ionol (4-methyl-2,6-di-tert.-butylphenol), which is produced by the reaction of p-cresol with isobutylene. Upon condensation of o-tert.-butyl-p-cresol with formaldehyde, the outstanding antioxidant-2246 (2,2-methylene-bis-4-methyl-6-tert.-butyl phenol) is produced. Thus antioxidants of the monophenol and bisphenol types are obtained based on the products of alkylation of p-cresol. Trialkylated phenols (products of 2,4-, 2,3-, 2,5-, 2,6-, 3,4- and 3,5-xylenols) are excellent antioxidants. Alkylated chlorophenols are also excellent antioxidants.