GB906655A - Substituted phenols - Google Patents

Abstract

Liquid hydrocarbon fuels and lubricants (both mineral oils and synthetic esters) are stabilized against oxidation by adding a small proportion (up to 5%) of a 2,6-disubstituted phenol having the formula <FORM:0906655/III/1> wherein A1 is a phenyl, alkylphenyl or phenyl-phenyl group, R1 is a C1 to C3 alkyl group, R2 is a hydrogen atom or a C1 to C3 alkyl group, and R is a C1 to C22 hydrocarbon group which may be of the same type as the other ortho-substituent. In Example 29, gasoline (comprising 7,3% olefins) containing tetraethyllead, ethylene dichloride ethylene dibromide and tris(beta-chloro-isopropyl) thionophosphate is stabilized with (6-(alpha-ethyl-alpha-propyl-p-monylbenzyl)-o-cresol. In Example 31, diesel oil is stabilized against oxidative deterioration with 0,3% of 6((alpha-methylbenzyl)-o-cresol. In Example 34, a petroleum lubricating oil is stabilized with 0,2% of 2-(alpha, alpha-diethyl-p-methylbenzyl)-6-tert-butylphenol. Examples 35 and 36 relate to the stabilization of pentaerythritol ester and dicoctyl sebacate with 2,6-bis(a -methylbenzyl)phenol and 6-(alpha-methylbenzyl)-o-cresol, respectively. For the preparation of the substituted phenols, see Group IV(b).ALSO:Natural and synthetic rubbers and synthetic polymers such as polyethylene are stabilized against oxidation by adding a small proprtion (up to 5%) of a 2,6-disubstituted phenol having the formula <FORM:0906655/IV(a)/1> wherein A1 is a phenyl, alkylphenyl or phenylphenyl group, R1 is a C1 to C3 alkyl group, R2 is a hydrogen atom or a C1 to C3 alkyl group, and R is a C1 to C22 hydrocarbon group which may be of the same type as the other ortho-substituent. Example 11 describes the use of 2-6-bis (alpha-methylbenzyl)phenol as an antioxidant for pale crepe rubber; the other components of the stock, before curing, being:-zinc oxide, titanium dioxide, stearic acid, ultramarine blue, sulphur and mercaptobenzothiazole. Examples 13, 16 and 20 also relate to the stabilization of natural rubber. Examples 12 and 15 relate to the stabilization of butadiene-styrene copolymer with 6-(alpha,alpha-dimethylbenzyl)-o-cresol and 2,6-bis-(alpha-methylbenzyl)phenol respectively. Examples 14 and 19 relate to the stabilization of butadiene-acrylonitrile copolymer with 6-(alpha-methylbenzyl)-o-cresol and 6-(alpha, alpha-dimethylbenzyl)-o-cresol, respectively. Examples 17 and 18 relate to the stabilization of butyl rubber with 2-(alpha-ethyl-4-methylbenzyl)-6-ethylphenol and 2-(alpha-propylbenzyl)-6-tert-amylphenol respectively. Examples 21 to 24 relate to the stabilization of polyethylene using 2,6-bis (alpha, alpha-dimethylbenzyl)phenol, 6-alpha-methylbenzyl)-o-cresol, 6-(alpha, alpha-dimethylbenzyl)-o-cresol, and 2,6-bis(alpha-methylbenzyl)phenol, respectively. For the preparation of the disubstituted phenols, (see Group IV(b)).ALSO:2,6-Disubstituted phenols having the formula <FORM:0906655/IV (b)/1> wherein A1 is a phenyl, alkylphenyl or phenyl-phenyl group, R1 is a C1 to C3 alkyl group, R2 is a hydrogen atom or a C1 to C3 alkyl group, and R is a C1 to C22 hydrocarbon group, which may be of the same type as the other ortho-substituent, are prepared by reacting a phenol, having a hydrogen atom attached to the aromatic ring in an ortho-position to the hydroxyl group, with styrene or an alkyl- or phenyl-substituted styrene in the presence of a catalyst such as an aluminium phenoxide. In Example 2, phenol (3 moles) is refluxed with aluminium turnings 1/6 mole); and then alpha-methylstyrene (6 moles) is added. The reaction is carried out at 150 DEG C. Benzene and diethyl ether are then added, followed by hydrochloric acid. The organic phase is separated, washed with warm water, and submitted to fractionation to obtain 2,6-di-(alpha, alpha-dimethylbenzyl)phenol. O-(alpha, alpha-dimethylbenzyl)phenol is obtained as byproduct; but this may be converted into 2-(alpha, alpha - dimethylbenzene) - 6 - tert-butylphenol by reaction with isobutylene. In Example 3, o-cresol is reacted, in the presence of aluminium cresoxide, with styrene to obtain 6-(alpha-methylbenzyl)-o-cresol. In Example 9, phenol is reacted at 200 DEG C. with alpha, p beta-diethyl-p-octylstyrene in the presence of a small amount of aluminium phenoxide. The product is 2,6-di-(alpha-ethyl-alpha-propyl-p-octylbenzyl)phenol. These substituted phenols are effective stabilizers and antioxidants for hydrocarbon fuels and lubricants (Group III) natural and synthetic rubbers, and polyethylenes (Group IV(a)).