GB815991A - Dibenzoate esters of aliphatic diols and process for their preparation - Google Patents

Abstract

The invention comprises a process for preparing dibenzoate esters of aliphatic diols wherein butyl benzoate is reacted with an aliphatic diol having 4 to 9 carbon atoms and no "tertiary hydroxyl groups," and also the dibenzoate esters of 2 - ethyl - 1 : 3 - hexanediol, 2 - methyl- or -ethyl - 1 : 5 - pentanediol, 2 - ethyl - 3 - methyl-or 2 : 4-diethyl-1 : 5-pentanediol and 2-ethyl-2-butyl- or 2-methyl-2-propyl-1 : 3-propanediol. A "tertiary hydroxyl group" is one which is attached to a tertiary carbon atom. Preferably, 1 mol. of the aliphatic diol is reacted with 2.5 mols. of butyl benzoate in the presence of an alkaline catalyst at a temperature of 100 DEG to 250 DEG C. and at a pressure from 0.1 mm. to 200 mm. Hg. Suitable catalysts are the alkali and alkaline earth metal oxides, hydroxides, alkoxides, carbonates and borates. Diols specified in addition to those in examples are 1 : 5-pentanediol and 2 : 5-hexanediol. In an example, butyl benzoate, dipropylene glycol and calcium oxide are mixed in a reaction vessel fitted with a stirrer and fractionating column, distilled in vacuo to give a first fraction of butanol, a mid-fraction of butanol and butyl benzoate and a final fraction of butyl benzoate, the residue is filtered to remove catalyst, stripped, treated with a decolorizing agent and filtered to give dipropylene glycol dibenzoate. Alternatively, the ester may be obtained as a fourth fraction in the vacuum distillation. The dibenzoate esters of the following diols are prepared similarly: diethylene glycol, 2-ethyl-1 : 3-hexanediol, 2 - methoxymethyl - 2 : 4 - dimethyl - 1 : 5 - pentanediol, 2 : 4 - diethyl- or 2 - methyl - 3 - methyl - 1 : 5 - pentanediol, 2- or 3-methyl- or 2-ethyl-1 : 5-pentanediol and 2 - ethyl - 2 - butyl- or 2 : 2 - diethyl- or 2-methyl-2-propyl-1 : 3-propanediol.