Process for preparing surfactant solutions with N-acyl amino acid salts

A process for preparing a surfactant solution with an N-acyl amino acid or its salt comprising

• a) preparing an alkali metal salt of an amino carboxylic acid in-situ by reacting the amino carboxylic acid and an alkali metal methoxide by a1) reacting the amino carboxylic acid with a solution consisting of an alkali metal methoxide in methanol in presence of a carboxyl glyceride ester or by a2) reacting the amino carboxylic acid with a solution consisting of the alkali metal methoxide in methanol and afterwards adding the carboxyl glyceride ester before
• b) forming the N-acyl amino acid salt by reacting the alkali metal salt of the amino carboxylic acid with the carboxyl glyceride ester by heating and under removal of methanol until at least 60 wt % of a theoretical amount of methanol was removed and
• c) afterwards applying vacuum and
• d) after releasing vacuum adding water to form a solution with the N-acyl amino acid salt
• e) and optionally adjusting the pH value.