Substd. phenol antioxidants esp. for high temp. use - prepd. e.g. from nitroalkane, (2,6)-ditertiary-butyl phenol and formaldehyde

摘要

New substd. phenol antioxidants are of formula Ar-C(R1)(R2)-NO2 (I) or Ar-ON(O)=C(R3)-Ar (II). In the formulae, Ar is 3,5-di-t-butyl-4-hydroxybenzyl; R1 and R2 are H, 1-4C alkyl or Ar; and R3 is 1-4C alkyl, opt. substd. by methoxy or ethoxy. They are prepd. by reacting a nitroalkane with 2 or 3 moles 2,6-di-t-butylphenyl and 2 or 3 mole formaldehyde in a polar water-miscible organic solvent at between room temp. and the reflux temp. of the solvent. A sec. nitroalkane, e.g. 2-nitropropane, is used to give (I) and a 2-4C prim. nitroalkane, e.g. nitroethane, to give (II). Alternatively the nitroalkane is reacted with 1-3 moles 3,5-di-t-butyl-4-hydroxybenzyl N, N-dialkylthiocarbonate, the nitroalkane being prim. with 2-4C, to give (II); or with 1-3 moles, 2,6-di-t-butyl-4-alkoxymethylphenol to give (I); or with formaldehyde, 2, 6-di-t-butylphenol and a lower aliphatic alcohol (when the nitroalkane is nitromethane) to give (II). They are less volatile than other antioxidants and are suitable for high temp. applications.