New diarylmethane derivatives, their manufacture and application as antioxidants

摘要

Age resistant synthetic rubber articles and stabilized synthetic rubber latices comprise a 2 : 21 - dihydroxy - 5 : 51 - dimethyldiphenyl - methane to the 3-position of which there is attached the tertiary carbon atom of a tertiary alkyl group of 4-8 carbon atoms and to the 31-position an a -alkyl cycloalkyl group, in which the cycloalkyl group is a cyclopentyl, methyl cyclopentyl, cyclohexyl or a methyl cyclohexyl group and the alkyl substituent has not more than 4 carbon atoms, and is attached to the a -carbon atom of the cycloalkyl group, i.e. the carbon atom which is joined to the phenyl radical, or a normal or basic aluminium, barium, calcium, magnesium, strontium or zinc salt thereof (see Group IV (b)). Synthetic rubbers mentioned include polymers of butadiene-1 : 3 and 2-chlorobutadiene-1 : 3 and copolymers of either of these compounds with acrylonitrile, styrene and methyl methacrylate. The antioxidants may be mixed with the rubber with the vulcanizing and other ingredients and cured at room or elevated temperature or they may be mixed with the rubber and other ingredients and vulcanized in the cold with sulphur monochloride.ALSO:The invention comprises 2:21-dihydroxy-5:51-dimethyldiphenyl methanes to the 3-position of which there is attached the tertiary carbon atom of a tertiary alkyl group of 4-8 carbon atoms and to the 31-position an a -alkylcycloalkyl group in which the cycloalkyl group is a cyclopentyl, methyl cyclopentyl, cyclohexyl or methylcyclohexyl one and the alkyl substituent has not more than four carbon atoms, and is attached to the a -carbon atom of the cycloalkyl group, i.e. the carbon atom which is joined to the phenyl radical and the normal and basic aluminium, barium, calcium, magnesium, strontium and zinc salts of these compounds. The compounds are prepared by a process which comprises interacting equimolecular proportions of two substituted cresols one from each of the two types of the general formul in which R1 stands for a tertiary alkyl group of 4-8 carbon atoms, attached to the benzene nucleus by the tertiary carbon atom, R2 stands for an a -alkyl cycloalkyl group, in which the cycloalkyl group is cyclopentyl, methylcyclopentyl, cyclohexyl or methylcyclohexyl and the alkyl group has not more than four carbon atoms and is attached to the a -carbon atom of the cycloalkyl group, i.e. the carbon atom which is joined to the phenyl radical and X stands for H or for either a -CH2OH or -CH2Cl group, subject to the condition that one and only one of the two cresols which are interacted carries either a -CH2OH group or a -CH2Cl group. One molecular proportion of a substituted cresol from one of the two types of the general formul may be combined with a molecular proportion of formaldehyde in the presence of a basic catalyst and the resulting product reacted with one molecular proportion of a substituted cresol of the other type. Alternatively, one molecular proportion of the one cresol may be interacted with one molecular proportion of formaldehyde in the presence of anhydrous hydrogen chloride and the resulting chloromethyl derivative then interacted with one molecular proportion of the other cresol. The normal and basic aluminium, barium, calcium, magnesium, strontium and zinc salts may be made by known methods of salt formation. In examples: 2:21-dihydroxy-3-a -methyl-cyclohexyl - 31 - tert. - butyl - 5:51 - dimethyldiphenylmethane is prepared by reacting in light petroleum 2-a -methylcyclohexyl-4-methylphenol, made by combining 1-methylcyclohexene and p-cresol in the presence of sulphuric acid, with aqueous formaldehyde in the presence of hydrogen chloride and reacting the product with 2-tert.-butyl-4-methyl-phenol; the corresponding 3-a ,g -dimethylcyclohexyl compound may be made in an analogous way using 2-a ,g -dimethylcyclohexyl - 4 - methyl phenol instead of 2 - a - methylcyclohexyl - 4 - methanolphenol (1); 2:21-dihydroxy-3-a -methylcyclohexyl - 31 - (1:1:3:3 - tetramethylbutyl)-5:51 - dimethyl - methane is similarly prepared using 2-(1:1:3:3-tetramethylbutyl)-4-methyl phenol in place of 2-tert.-butyl-4-methyl phenol (3); 2:21-dihydroxy-3-a -methylcyclopentyl - 31 - tert. - butyl - 5 : 51-dimethyldiphenyl methane is similarly prepared using 2-a -methylcyclopentyl-4-methylphenol in place of 2-a -methylcyclohexyl-4-methylphenol (4); and 2 : 21-dihydroxy-3-a -methylcyclohexyl - 31 - tert. - butyl - 5 : 51 - dimethyldiphenylmethane is obtained by heating 2 - hydroxy - 3 - tert. - butyl - 5 - methylbenzyl alcohol, obtained by treating 2-tert.-butyl-4-methylphenol with formation in the presence of sodium hydroxide, with 2-a -methylcyclohexyl-4-methylphenol in the presence of hydrogen chloride. The products, and e.g. their metal salts, are antioxidants for natural and synthetic rubbers (see Groups IV (a) and V) and oils, fats and waxes.ALSO:Antioxidants for oils, fats and waxes which tend to deteriorate in the presence of oxygen are 2 : 21 - dihydroxy - 5 : 51 - dimethyldiphenylmethanes. to the 3 - position of which there is attached the tertiary carbon atom of a tertiary alkyl group of 4 - 8 carbon atoms and to the 31 - position an a - alkylcyclo - alkyl group in which the cycloalkyl group is a cyclopentyl, methyl - cyclopentyl, cyclohexyl or methyl - cyclohexyl group and the alkyl substituent has not more than 4 carbon atoms and is attached to the a - carbon atom of the cycloalkyl group, i.e. the carbon atom which is joined to the phenyl radical. Normal and basic aluminium, barium, calcium, strontium, magnesium and zinc salts thereof may also be used.ALSO:Age-resistant natural rubber and rubber articles and stabilized rubber latices comprise a 2 : 21-dihydroxy-5 : 51-dimethyldiphenylmethane to the 3 position of which there is attached the tertiary carbon atom of a tertiary alkyl group of 4-8 carbon atoms and to the 31 position an -alkyl cycloalkyl group, in which the cycloalkyl group is cyclopentyl, methyl cyclopentyl, cyclohexyl or methyl cyclohexyl and the alkyl substituent has not more than 4 carbon atoms and is attached to the -carbon atom of the cycloalkyl group, i.e. the carbon atom which is joined to the phenyl radical or a normal or basic aluminium, barium, calcium, magnesium, strontium or zinc salt thereof (see Group IVb). The antioxidants may be employed in the manufacture of rubber and rubber articles according to the normal methods, e.g. they may be mixed with the rubber and the vulcanizing ingredients and cured or they may be mixed with rubber and other compounding ingredients and vulcanized with sulphur monochloride in the cold. Vulcanizable rubber stocks are prepared, in examples, from compositions comprising pale crepe rubber, zinc oxide, blanc fixe, stearic acid, sulphur, diphenyl guanidine and 2:21-dihydroxy-3- -methylcyclohexyl - 31 - tert-butyl-5 : 51-dimethyldiphenylmethane (2); pale crepe rubber, zinc oxide, blanc fixe, stearic acid, titanium dioxide, sulphur, zinc diethyldithiocarbamate and 2 : 21-dihydroxy-3- -methylcyclohexyl-31-(1 : 1 : 3 :3-tetramethylbutyl)-5 : 51 - dimethyldiphenylmethane (3) and as antioxidant in a similar composition 2 - - methylcyclopentyl - 4 - methylphenol (4). The rubber stocks are cured and subjected to ageing tests together with stocks of similar composition for comparison.