Method for the preparation of a highly concentrated, flowable and pumpable betaine solution

A method for the preparation of a flowable and pumpable solution containing at least 70 weight percent of betaine of the following general formula ##STR3## in which R.sup.1 is the alkyl group of a fatty acid or a fatty acid mixture with an average of 6 to 18 carbon atoms, R.sup.2 and R.sup.3 are the same or different and represent an alkyl or a hydroxyalkyl group with 1 to 4 carbon atoms, x has a value of 2 or 3 and y a value of 1, 2, 3 or 4, said method comprising the steps of quaternizing at elevated temperature a compound of the general formula R.sup.1 CONH(CH.sub.2).sub.x NR.sup.2 R.sup.3 with the salt of a halogencarboxylic acid X(CH.sub.2).sub.y COOMe, in which X is halogen and Me is a monovalent cation, wherein

• (a) the R.sup.1 group is selected so that the compound of the formula R.sup.1 CONH(CH.sub.2).sub.x NR.sup.2 R.sup.3 has a melting point of at the most 30.degree. C.,
• (b) said quaternization being carried out
• (b.sub.1) with the potassium or ammonium salt of the halogencarboxylic acid X(CH.sub.2).sub.y COOH,
• (b.sub.2) in an organic polar solvent, which contains at the most 20 weight percent of water, said polar solvent being a monovalent aliphatic alcohol having 2-4 carbon atoms, and wherein
• (c) after the quaternization, any water contained in the reaction mixture is distilled off azeotropically and the precipitated potassium or ammonium halides is removed,
• (d) whereupon the solvent is distilled off partly or completely, and
• (e) before, simultaneously with or after the distillation, the concentration of the betaine in the solvent or the solvent mixture is adjusted to at least 70 weight percent with an aliphatic dialcohol with 2-4 carbon atoms or a mixture of an aliphatic dialcohol and an aliphatic monoalcohol with 2 to 4 carbon atoms.