GB806197A - Improved method for the production of esters of unsaturated acids - Google Patents

Abstract

Compounds of the general formula CH2 = CX.COOR, in which X and R are hydrogen or C1-4 alkyl groups, are reacted under acid esterifying conditions with a mixture of alcohols containing about 10-20 carbon atoms commercially known as lauryl alcohol, in the presence of catechol as a polymerization inhibitor, the reaction mixture being extracted with aqueous alkali and the lauryl ester recovered. The inhibitor is suitably used in concentrations of about 1 per cent or more based on the weight of reactants, preferred concentrations being about 2 to 4 per cent. The reactants may be heated in an inert solvent with an acid catalyst such as sulphuric acid or p-toluene sulphonic acid, suitable concentrations of catalyst being greater than 0.25 per cent by weight of the total charge. When esters are used as starting material it is convenient to use an inert entraining liquid as solvent, so as to remove the lower alcohol formed; or with methyl methacrylate, excess may be used, and methyl alcohol removed azeotropically with the excess ester. Molar quantities of reactants may be used, but preferably excess of the acrylic component is employed. The reaction may be carried out at the boiling point of the mixture, e.g. under distillation conditions, suitably at 90 DEG to about 150 DEG C., until no more water or alcohol of reaction is removed. It is advantageous to add active carbon, e.g. about 2 to 5 per cent of the reactants. After the reaction the mixture is washed with aqueous alkali, e.g. sodium hydroxide of about 5-10 per cent by weight. After separation of the layers the organic layer is preferably filtered with a filter aid, such as diatomaceous earth. The lauryl ester may be recovered by distillation of excess acrylic acid or its derivative and solvent under reduced pressure, preferably not allowing the base temperature to rise above about 80 DEG C. In examples, the lauryl alcohol mixture is reacted with methyl methacrylate.