GB852932A - Rubber antidegradants - Google Patents

Abstract

In rubber there is incorporated, as antidegradant, a compound of the formula: <FORM:0852932/IV(a)/1> where R1 is an aliphatic or aralkyl group and R2 an alkyl or cycloalkyl group containing 6 or more carbon atoms or an aralkyl group, and where the benzene ring may contain an inert substituent, or a salt of one of these substituted anilines. The preferred anti-degradants are those where R1 is a primary, secondary or tertiary lower alkyl group, a cycloalkyl group or a benzyl group, R2 a primary or secondary alkyl group, a cyclohexyl group or a benzyl group and where the benzene ring is unsubstituted in the positions ortho to the amino group but may bear for example alkyl groups in the meta positions. The anti-degradent may be used in natural or synthetic rubbers in an amount between 0,5-2% by weight. Examples describe compositions based on pale crepe rubber, smoked sheets and styrene-butadiene copolymer, and physical properties of the compositions containing specified anti-degradants are given.ALSO:The invention comprises N-substituted anilines of the formula: <FORM:0852932/IV(b)/1> where R1 is an alkyl, cycloalkyl or aralkyl group and R2 is an alkyl or cycloalkyl group containing 6 or more carbon atoms and where the benzene ring can contain an inert substituent, and their salts, provided that where R2 contains 6 carbon atoms R1 if an aralkyl group is a benzyl group and where R2 is a cyclohexyl group the total number of carbon atoms in R1 and in any inert substituent of the benzene ring is at least 2. The compounds may be prepared by reductive alkylation of an amine <FORM:0852932/IV(b)/2> (or a suitable nitrogen-containing precursor of the amine, e.g. a nitro, nitroso, azo or hydrazo compound) in the presence of an aldehyde or ketone from which the group R2 can be derived by reduction. The reductive alkylation may be carried out catalytically by means of hydrogen. The compounds may also be prepared by alkyllating the N-unsubstituted aniline with an alkyl halide R2-hal preferably in the presence of an acid-acceptor. Salts, e.g. quaternary chlorides or hydrochlorides may be prepared in the usual manner. The compounds find application as rubber anti-degradants (see Group IV(A)). Examples describe the preparation of the following substituted anilines:4-ethoxy-N-11, 31-dimethyl-n -butyl, 4-ethoxy-N-cyclohexyl, 4-benzyloxy-N-11, 31-dimethyl-n-butyl, 2-methyl-4-methoxy-N-cyclohexyl, 4-ethoxy-N-n-hexyl, 4-methoxy-N-n-hexyl, 4-ethoxy-N-n-hexadecyl, and 2, 6-di-methyl-4-methoxy-N-n-octyl-aniline. Benzyl-4-nitrophenyl ether is prepared from potassium p p-nitrophenate and benzyl chloride. 2-methyl-4-methoxy-azobenzene is prepared by treating sodium m-cresate with phenyldrazonium chloride and methylating the resulting 2-methyl-4-hydroxy-azobenzene. 2,6-dimethyl-p-anisidine is prepared by coupling 3,5-xylenol with sodium benzenediazotate to give 3,5-dimethyl-4-phenylazophenol which is methylated to 3,5-dimethyl-4-phenylazoanisole and then reduced.