GB714772A - Improvements in or relating to the treatment of natural and synthetic rubbers - Google Patents

Abstract

Substituted resorcinols which may be used as rubber antioxidants (see Group V) may be prepared as follows: (a) 4-ethyl-resorcinol was prepared by catalytic reduction of 2,4-dihydroxyacetophenone in cyclohexane solution at 60 DEG C. and 700 lb./square inch hydrogen pressure using Raney nickel as catalyst, or by acetylating resorcinol using conc.H2SO4 and then reducing the resulting ketone by amalgamated zinc and hydrochloric acid; (b) 4,6-dibenzyl-resorcinol was prepared by reacting one gm. mol. of resorcinol with 2 gm. mols. of benzyl chloride and zinc dust; (c) 4-octadecyl-resorcinol was obtained by reducing the ketone obtained by rearranging the mono-stearate of resorcinol by means of sulphuric acid.ALSO:Natural or synthetic rubber is preserved by treating it with a derivative of resorcinal having in the 4-position or in the 4 and 6-positions one or two alkyl, aralkyl, cycloalkyl or naphthenic hydrocarbon groups. The resorcinol compounds may be those in which the substituting groups are:-4-methyl, 4-ethyl, 4, 6- diethyl, 4-isopropyl, 4, 6-di n propyl, 4-(di-isopropylmethyl), 4-(tertiary butyl), 4, 6-di (tertiary butyl), 4, 6-(di tertiary amyl), 4-n.-hexyl, 4-iso octyl, 4, 6,-di (iso-octyl), 4-octadecyl, 4-octadecenyl, 4-benzyl, 4, 6-dibenzyl, 4-ethyl benzyl, 4-a phenyl ethyl, 4-cyclohexyl and 4, 6-dicyclohexyl. These compounds may be made according to the methods described in Group IV(b). In Examples, the oxidation of a mix consisting of crepe cuttings, zinc oxide, dibenzthiazyl disulphide, tetramethyl-thiuram disulphide, lithopone, stearic acid and sulphur was reduced by adding one or more of the above resorcinol derivatives.