A standard method for the preparation of N-acylamino acids is the Schotten-Baumann reaction, in which oleoyl chloride (from oleic acid and, e.g. phosphorus trichloride) is added to an aqueous solution of N-methylglycine at pH 10 (kept constant by the addition of sodium hydroxide solution).
Fatty acid-free N-oleoylsarcosine is obtained as an oil. The method is not suitable for industrial surfactant synthesis because of the relatively expensive production of the carboxylic acid chlorides and the expensive disposal of the phosphonic acid obtained as a byproduct.
N-Oleoylsarcosine can be obtained in the reaction of oleic acid, N-methylglycine and its sodium salt at 170 °C for 8 to 10 hours upon elimination of water.
More gentle conditions (120 °C) and shorter reaction times (3.5 hours) can be used when methyl oleate is reacted with sodium N-methylglycinate upon the addition of equimolar amounts of sodium methoxide in methanol. After absorption in water, acidification with concentrated sulfuric acid and extraction with butanone, N-Oleoylsarcosine is obtained in 92.5% yield.