GB860242A - Improved esterification process - Google Patents

Abstract

Polyvinyl chloride is stabilized with cadmium naphthenate and barium ricinoleate and plasticised with a decyl phthalate of improved colour resistance prepared by esterifying phthalic anhydride with decyl alcohol in the presence of formamide. Specification 802,860 is referred to.ALSO:A process for preparing esters from an acidic compound and an alcohol at elevated temperatures in the presence of a conventional esterification catalyst is characterized in that a colourinhibiting stabilizer consisting of (a) one or more primary amides, hydroxylamine or its salts, ammonium compounds or a mixture of an alkali metal borohydride and a primary amide or (b) an alkali metal borohydride which has been aged in the alcohol for at least one day prior to the esterification, is added to the mixture of acidic compound and alcohol during esterification or to the alcohol before esterification. The process is particularly directed to the production of plasticizer esters, e.g. octyl or decyl phthalate, where colourless products are desirable. The preferred proportions of colour inhibitor are 0.01 to 1% by weight based on the alcohol of amide, 0.01 to 1.5% by weight based on the alcohol of hydroxylamine or salt thereof, 0.1 to 4.0 mol. per cent based on the alcohol of ammonium compound, a mixture of 0.01 to 1 weight per cent based on the alcohol of primary amide and 0.001 to 0.03 weight per cent based on the alcohol of alkali metal borohydride or 5 to 300 p.p.m. based on the alcohol of alkali metal borohydride. The term "alkali metal borohydrides" includes organic alkali metal borohydrides, e.g. mono-, di- or tri-alkyl, alkoxy or carboxy derivatives. The esterification is otherwise carried out in a known manner and examples relate to the esterification of phthalic anhydride with a C8 or C10 oxo alcohol in the presence of sulphuric acid or p-toluene sulphonic acid and a toluene water-entrainer. The examples illustrate the use of formamide, acetamide, benzamide, hydroxylamine hydrochloride, ammonium chloride, sulphate, formate and acetate, sodium borohydride and mixtures of sodium borohydride and formamide and the ester colour ratings (Hazen or Garder scale) given and compared to those of esters prepared in the absence of the inhibitors. The invention also includes a stabilized alcohol suitable for use in preparing colour-free esters comprising a mixture of the alcohol, contaminated with minor proportions of carbonyl or carbonyl-forming compounds or mixtures thereof and a stabilizer consisting of one or more primary amides, hydroxylamine or salts thereof, ammonium compounds, an alkali metal borohydride or a mixture of an alkali metal borohydride and a primary amide. The stabilized alcohol may be washed with water to remove the inhibitor before it is used for esterification. Examples refer to the addition of hydroxylamine hydrochloride, ammonium formate and chloride and sodium borohydride to a C10 oxo alcohol. Specification 802,860 is referred to.