Method for preparing high-content alpha-lauryl betaine by solvent-free quaternization

Abstract

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.

Description

technical field [0001] The invention discloses a method for preparing high-content α-alkyl betaines by solvent-free quaternization, which belongs to the technical field of organic synthesis. Background technique [0002] Betaine is an amphoteric compound first isolated from sugar beet by Kruger, also known as N,N,N-trimethylglycine inner salt or betaine. When a methyl group on the N atom is replaced by other alkyl groups, The amphoteric compounds are called N-alkyl betaines; when the methylene groups are replaced by other alkyl groups, the amphoteric compounds are called a-alkyl betaines. When the substituted alkyl group has 8 carbons or more, the members of the two series have surface activity, which are called N-alkyl betaine amphoteric surfactant and a-alkyl betaine betaine amphoteric surfactant respectively. , commonly known as carboxybetaine amphoteric surfactants. [0003] In the traditional carboxybetaine synthesis process, water is used as the reaction medium. Afte...

AI Technical Summary

Problems solved by technology

The core of the new process is to make trimethylamine, one of the reaction materials, liquefied under autoclaving and then serve as the reaction medium at the same time, which skillfully solves the difficulties of increasing the concentration of the reaction materials in the aqueous phase and the problems of mass and heat transfer; avoiding the use of external solvents , so as to curb the occurrence of side reactions, especially hydrolysis side reactions, and effectively improve the yield and purity of α-alkyl betaines; after the reaction, trimethylamine is recovered by evaporation and recycled, and the final product α-alkyl betaines is high content of solid products, and the preparation process achieves zero emissions

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