Main Reagents and Instruments
Methyl cocoate, industrial product, American Stepan Co., Ltd.; N, N-dimethyl-1,3-propylenediamine, industrial product, Guangzhou Tianci High-tech Materials Co., Ltd.; Chloroacetic acid, industrial product, Aksu Nobel Ltd. GS-1 magnetic drive autoclave, Weihai Chemical Machinery Co., Ltd.; LCQ Deca XP liquid mass spectrometer, Thermoelectric Corporation of America; LC-10AT high performance liquid chromatography, Shimadzu Corporation of Japan; IR 200 Fourier transform infrared spectrometer, American Nicholas Company.
Synthesis of Cocamidopropyl Dimethylamine
Add 2.875 mol of N,N-dimethyl-1,3-propylenediamine, 2.500 mol of methyl cocoate, and an appropriate amount of catalyst KOH to the magnetically driven autoclave, seal the reactor, and fill the reactor with nitrogen to replace the air , start magnetic stirring, heat to 210°C, and react for 25 minutes. After the reaction is completed, the excess N,N-dimethyl-1,3-propylenediamine and the methanol produced by the reaction are removed in vacuum.
Synthesis of Cocamidopropyl Betaine Natural
Add 0.600 mol of cocamidopropyl dimethylamine and appropriate amount of water to a 1L four-neck glass flask, stir and raise the temperature, and add the chloroacetic acid (0.618 mol) solution neutralized with NaOH solution in advance after reaching 80°C, and heat Keep at 80-90°C, and react at constant temperature for 3 hours. After the reaction, cool down to below 40°C, and add hydrochloric acid or NaOH to adjust to the required pH.
Determination of conversion rate of fatty acid methyl ester
With reference to the method for measuring the average relative molecular mass of free amines (i.e. fatty amidopropyl dimethyl tertiary amine) by gas chromatography in QB/T4082-2010, the unreacted coconut oil in cocoamidopropyl dimethylamine is determined by gas chromatography acid methyl ester to obtain its conversion.