Preparation of diethyl phosphoric acid

Abstract

The invention relates to a process for preparing triethyl phosphate by reacting phosphorus oxychloride with a greater than stoichiometric quantity of ethanol under reduced pressure at temperatures of from 0 to 50 DEG C. in a reaction vessel, whereina) the volatile components resulting from the reaction are predominantly condensed by means of a reflux condenser and the remaining volatile components are passed into a scrubber filled with water,b) after the end of the reaction, the reaction mixture is separated distillatively in an outgassing column into a top product and a bottom product which predominantly comprises triethyl phosphate,c) the top product of the outgassing column is combined with the contents of the scrubber and d) the contents of the scrubber are separated distillatively in an azeotropic distillation to obtain water and ethanol as top product and the ethanol, preferably after dewatering, is preferably returned to the reaction.

Description

field of invention

[0001] The invention relates to a method for preparing triethyl phosphate by reacting phosphorus oxychloride with ethanol. technical background

[0002] Trialkyl phosphates are very versatile. For example, it is used as a plasticizer, non-reactive flame retardant, hardener and accelerator in plastics and coatings, and as an auxiliary agent in textiles and paper products. They are also used in the chemical industry as wetting agents, flotation agents, defoamers, emulsifiers, stabilizers or extractants.

[0003] Various methods are known for the preparation of trialkylphosphates from phosphorus oxychloride and the corresponding alcohols. In the past, attempts were made to improve the preparation method from the aspects of reaction temperature, ratio of ingredients used and transfer of heat of reaction. A problem in the reaction of these two components is the formation of hydrogen chloride, which must be removed very quickly and completely from the reactio...