Patent GB-654841-A (GB)
Title: Improvements in or relating to the production of esters of secondary alcohols
IPC: C07C69/80
Filed: 1947-09-03
Abstract: Carboxylic esters of secondary alcohols are made by reacting a secondary alcohol with an ester of the carboxylic acid and a primary alcohol having less than 8 carbon atoms in the molecule and of lower boiling point than the secondary alcohol, in the absence of moisture, at a temperature low enough to avoid olefine formation and in the presence of an alkaline esterification catalyst which is gradually added over the period of reaction, and the lower boiling alcohol is continuously removed, e.g. by distillation.  In this way esters are obtained which due to the absence of colour are used as plasticizers for synthetic resins. Preferably the temperature does not exceed 150 DEG  C. and is controlled by the use of a low boiling solvent or reduced pressures.  Reaction may be effected by adding an excess of alcohol over that required to replace the primary alcohol of the ester and distilling with a low boiling water entraining solvent, or applying a vacuum, to remove moisture before addition of catalyst. The catalyst may be the sodium alkoxide corresponding to the alcohol of the primary ester.  Primary alcohol esters specified are lower alcoholic esters of phthalic, sebacic and other high boiling dibasic acids and high boiling monobasic acids such as lauric, stearic, trimethyl hexoic acid, and like fatty acids or mixtures thereof obtainable, e.g. from coconut oil. Secondary alcohols specified are straight chain alyphatic secondary alcohols, e.g. octanol 2, mixed secondary alcohols obtained by hydrating olefines, cyclic alcohols obtained by reducing phenols, e.g. cyclo-hexanol, and alcohols such as tetralol and phenyl methyl carbinol obtained as autoxidation products of hydrocarbons.  Catalysts specified are sodium, potassium and magnesium alkoxides, but any alkaline catalyst effective below 150 DEG  C. may be used.  The effectiveness of the process may depend on the efficiency of the fractionation column used.  Thus, if a good column is used isopropyl phthalate may be made from methyl phthalate and isopropyl alcohol although if ethyl phthalate is substituted for methyl phthalate the closeness of the B. Pts. of ethyl and isopropyl alcohol renders the preparation of isopropyl phthalate impracticable. In examples: (1) water is removed from mixed dimethyl phthalate and octanol-2 by entrainment distillation with benzene, sodium in methanol added slowly whilst methanol is removed at 70-80 DEG  C. and the product recovered by vacuum distillation after washing with water, a small amount of methyl octyl phthalate is also obtained, and in (2) water is removed from mixed dethyl phthalate and octanol 4 by vacuum treatment at 25 DEG  C., preferably in the presence of an entrainer such as benzene or toluene, sodium in ethanol is added while maintaining the vacuum at 10-50 m.m.s. and the temperature at 25 DEG  C., and ethanol removed and product recovered as in (1). Specification 654,842 is referred to.  The Provisional Specification contains a reference to the use of substituted carboxylic acid and derivatives of cyclohexanol.