The invention discloses a method for preparing high-content alpha-
lauryl betaine by
solvent-free quaternization, which belongs to the technical filed of
organic synthesis. Particularly, a hot-press condition is implemented for quaternization of
trimethylamine and alpha-halogenated
carboxylic acid, and the
trimethylamine which is one of reaction materials is liquefied under the hot-press condition and is simultaneously used as a reaction medium, so that the problem of difficulty in enhancing the reaction material concentration,
mass and
heat transfer and the like is solved skillfully; and an additional
solvent is avoided being used, so that quaternization is undergone under the
solvent-free condition to synthesize alpha-
lauryl betaine, particularly alpha-long-chain
lauryl betaine, serving as an amphoteric surfactant. The technology disclosed by the invention can be implemented under the solvent-free condition, so that the hydrolytic
side reaction of alpha-halogenated
carboxylic acid in an
aqueous solution is avoided, the yield of alpha-lauryl
betaine is effectively increased, or the product
pollution and the environmental
pollution caused by the use of an
organic solvent are avoided, and the product purity is remarkably increased; and the method has a simple process, excessive
raw material, namely
trimethylamine, is recycled after being evaporated and recovered, an end product, namely alpha-lauryl
betaine is a high-content
solid-state product, and a preparation process is emission-free.