Process for the preparation of pure aqueous betaine solutions

摘要

The process described relates to the preparation of aqueous betaine solutions by reaction of a tertiary amine with an omega -monohalocarboxylic acid, preferably monochloroacetic acid, and an alkali metal hydroxide in the presence of water, which solutions are said to be highly pure particularly in respect of the tertiary starting amine and omega -monohalocarboxylic acid. This is achieved by first reacting the three reaction components in a certain molar ratio with the aim of obtaining a betaine solution which comprises only a tolerated amount of starting amine. This aqueous betaine solution is then treated with a sulfonating agent, preferably with an alkali metal sulfite, alkali metal pyrosulfite or alkali metal bisulfite, for conversion of the omega -monohalocarboxylic acid present into the corresponding sulfocarboxylic acid, which is not troublesome. The process described is simple to carry out and leads to the highly pure aqueous betaine solutions mentioned.