Patent GB-864696-A (GB)
Title: Nuclear alkylation of aromatic compounds containing a hydroxyl group
IPC: C07C37/14
Filed: 1958-06-19
Abstract: Hydroxyl-containing nuclearly-alkylated aromatic compounds, obtained by reacting a monohydroxy aromatic compound, such as phenol or a cresol or naphthol, with styrene and at least one unsaturated hydrocarbon having at the olefinic bond a quaternary carbon atom in presence of a Friedel Crafts catalyst or a bleaching earth, are used as age-resisters for natural rubber or elastomeric polymers.  The unsaturated hydrocarbon having a quaternary carbon atom may be formed in situ in the reaction medium from the corresponding secondary or tertiary alcohol if there is used a catalyst which simultaneously has a dehydrating effect.  Specified compounds having a quaternary carbon atom include a -methyl styrene, a -alkyl cyclopentenes and cyclohexenes, isobutylene, 2, 2, 4-trimethyl-3-tert. butyl pent-3-ene, isododecylene, camphene, a -and b -pinene.  Specified polymers with which the age-resisters may be used are polymers of buta-1, 3-diene, 2-chloro-buta-1, 3-diene, and isoprene, and copolymers of these with styrene, acrylonitrile, acrylic and methacrylic esters, vinyl methyl ketone, asym. dichloroethane, and isobutylene.  Mixtures of these polymers with one another or with natural rubber may be used.  In examples, age-resisting compositions are prepared by mixing pale crepe rubber with heavy spar, titanium dioxide, zinc oxide, stearic acid, tetramethyl thiuram sulphide, sulphur, and as age-resister 1% based on the crepe rubber of a nuclear alkylation product of phenol with styrene and a -methyl styrene, or of o-cresol with styrene and a -methyl styrene, or of phenol with styrene and di-isobutylene, or of phenol with styrene and a -methyl cyclohexanol, and vulcanizing the mixtures.  In another example, a nuclear alkylation product of o-cresol with styrene and a methyl styrene is mixed with a 30% latex of a co-polymer of butadiene and styrene in a proportion of 2,5% based on the weight of the copolymer. The latex is coagulated and then dried.  The stabilized co-polymer is then mixed with magnesium silicate, stearic acid, zinc oxide, glycerine, dioctyl phthalate, disulphide of 2mercapto-benz-thiazole, hexamethylene tetramine, and sulphur, and the mixture is vulcanized by heating.  Specification 516,936 is referred to.ALSO:Hydroxyl - containing nuclearly - alkylated aromatic compounds are obtained by reacting a monohydroxy aromatic compound, e.g. phenol or a cresol or naphthol, with styrene and at least one unsaturated hydrocarbon having at the olefinic bond a quaternary carbon atom (i.e. a carbon atom to which no hydrogen atom is attached) in the presence of a Friedel Crafts catalyst or a bleaching earth.  The name Friedel Crafts catalyst is used to include hydrogen chloride and bromide, zinc chloride, phosphoric acid, sulphuric acid, aliphatic and aromatic sulphonic acids.  As unsaturated hydrocarbon having a quaternary carbon atom there may be used a -methyl styrene, a -alkyl cyclopentenes or cyclohexenes, isobutylene, 2-methyl but-1-ene, 2-methyl but-2-ene, 2, 2, 4-trimethyl pent-4-ene, 2, 2, 4-trimethyl-3-tert. butyl pent-3-ene, isononylene, isododecylene, camphene, a -pinene, and b -pinene.  In the mixture comprising styrene and an unsaturated hydrocarbon having a quaternary carbon atom, the latter compound may amount to 10-90% of the weight of the mixture.  From 1 to 3 mols of the mixture of olefinic compounds may be reacted with 1 mol of the aromatic hydroxy compound.  The products obtained are liquids of low viscosity.  The nuclear alkylation may take place at 50-150 DEG C.  If a catalyst is used which simultaneously has a dehydrating effect, as is the case when using an activated bleaching earth, the unsaturated compounds may be used in the form of their secondary or tertiary alcohols.  Thus instead of an a -alkyl cyclohexene there may be used a 2-alkyl-cyclohexan-1-ol, and instead of isobutylene there may be used tertiary butanol.  The alcohols used in this way are dehydrated in the reaction mixture by the action of the catalyst to the corresponding olefines which then react with the aromatic hydroxy compound.  If desired, instead of reacting the aromatic hydroxy compound with a mixture of the olefine compounds, it may be reacted first with the styrene and then with the unsaturated hydrocarbon which has a quaternary carbon atom, or the order of these reactions may be reversed.  The nuclearly-alkylated compounds may be used as age-resisters in natural rubber or synthetic rubber-like polymer compositions.  In Examples, (1) phenol (1 mol) is heated with a mixture of styrene (1,1 mol) and a -methyl styrene (1,1 mol) in presence of a bleaching earth; (2) o-cresol (1 mol) is heated with a mixture of styrene (1,25 mol) and a -methyl styrene (0,75 mol); (3) phenol (1 mol) is heated with styrene (1 mol) and di-isobutylene (1 mol); (4) phenol (1 mol) is heated with styrene (2 mols) and a -methyl cyclohexanol (1 mol) in presence of a bleaching earth; o-cresol is heated with a mixture of styrene and 2-methyl but-2-ene or 2, 2, 4-trimethyl-3-tert. butyl-pent-1-ene in presence of bleaching earth; o-cresol (1 mol) is heated with styrene (1 mol) and a -pinene (1 mol) in presence of anhydrous zinc chloride. Specification 516,936 is referred to.