Patent GB-822693-A (GB)
Title: Hydroxybenzyl ethers and their use as age-resisters
IPC: C07C43/178
Filed: 1958-03-11
Abstract: The invention comprises compositions of natural or synthetic rubbers with an antioxidant of general formula <FORM:0822693/IV (a)/1> where R1 and R2 are alkyl, aryl, aralkyl, or cycloalkyl, R3 is alkyl, aryl or hydrogen, and R4 is alkyl or cycloalkyl.  Radicals specified for R1 and R2, which may be the same or different, are tert.-butyl, cyclohexyl, cumyl, methyl, alphamethyl cyclohexyl, sec.-butyl, cyclopentyl, 21-methyl cyclohexyl, 11-phenylethyl, isopropyl, a -phenyl ethyl and tertiary aryl.  Radicals specified for R4 are isopropyl, methyl, ethyl, cyclohexyl, dodecyl and octyl.  Aldehydes specified from which <FORM:0822693/IV (a)/2> is formed are formaldehyde, isobutyraldehyde, n-butyraldehyde and benzaldehyde. The compounds may be added in from 0.1 to 5% by weight of the elastomer, e.g. those obtained from butadiene, dimethyl butadiene, isoprene and homologues or their copolymers with compounds such as styrene, a -methyl styrene, acrylonitrile, methacrylonitrile, acrylates and methacrylates, also copolymers obtained from isobutylene with a small proportion of conjugated diolefines. Polymerizates obtained from chlorobutadiene and its co-polymerizates obtained with mono and/or di-olefines or other polymerizable vinyl compounds may also be used.  The antioxidants may be added to the raw mixtures, to the vulcanizates or to the rubber latices, for example in the form of a dispersion.  Mixtures of the antioxidants with other known antioxidants may also be used.  Examples illustrate the mechanical properties of vulcanized compositions of light crepe rubber, zinc oxide, stearic acid, tetramethyl thiuram monosulphide, titanium dioxide, blanc fixe and sulphur with (a) no antioxidant, (b) phenolstyrene reaction product, and (c) various compounds of the invention, and the storage of a butadiene-styrene copolymerizate containing (a) no stabilizer, (b) phenol-styrene reaction product and (c) 2,4-di-tert.-butyl-4-hydroxybenzyl methyl ether.ALSO:The invention comprises compounds of the general formula <FORM:0822693/IV (a)/1> where R1 and R2 are alkyl, aryl, aralkyl or cycloalkyl, R3 is alkyl, aryl or hydrogen, and R4 is alkyl or cycloalkyl.  The compounds may be prepared by reacting a phenol substituted in the 2 and 6-position, with an aromatic or aliphatic aldehyde in alcoholic solution in the presence of compounds having an alkaline reaction. Radicals specified for R1 and R2, which may be the same or different, are tert.-butyl, cyclohexyl, cumyl, methyl, alpha methyl cyclohexyl, sec.-butyl, cyclopentyl, 21-methyl cyclohexyl, 1-phenylethyl, isopropyl, a -phenyl ethyl, and tertiary amyl. Radicals specified for R4 are isopropyl, methyl, ethyl, cyclohexyl, dodecyl, octyl. Aldehydes specified from which <FORM:0822693/IV (a)/2> is formed are formaldehyde, isobutyraldehyde, benzaldehyde, and n-butyraldehyde. Examples of compounds having an alkaline reaction and suitable for use in the reaction are sodium, potassium, and lithium hydroxides, sodium or potassium cyanides, and tertiary aliphatic organic bases such as trimethylamine.  The reaction proceeds at room or elevated temperature and the hydroxy ether formed may be separated in known manner.  Examples are given of the preparation of many compounds of the stated general formula.