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Betaine surfactants because of their unique properties, water-soluble, salt ability, low toxicity and irritation, high foaming resistance, and other surface active agents with an excellent effect of the complex, in industrial applications and scientific research and more attention to the natural fatty acids as raw material, through a two-step synthesis of α-long chain alkyl betaine, this method has low prices of raw materials, synthetic procedure is simple, high conversion rate, the product is superior overall performance and some advantages. Amphoteric surfactants such synthetic steps are divided into two steps: first, to natural fatty acids and chlorine as a raw material, chlorosulfonic acid as the catalyst, and oxygen as a radical trapping agent, α-chloro fatty acid synthesis; second step to α-chloro short chain fatty acids and tertiary ammonium trimethylamine as raw materials, the synthesis of the pressure and heat conditions α-long chain alkyl betaines. This topic is conducive to industrial scale from the perspective of the reaction process and the implementation of optimization of process conditions, chose a cost-effective process route and the corresponding method. In this experimental range get the following main results and conclusions: the use of gas chromatography (GC) method for the determination α-CDA content, while taking advantage of the relative density (RD) method for the determination of the sample corresponds to the density of the coupling α-chloro lauric acid content RD values ??change throughout the course of the reaction between coupling method established GC-RD control lauric acid reaction of α-chloro-depth. According to α-chloro-lauric acid content and RD coupling diagram in a chlorinated reaction process, when the density of 0.9652 is α-chloro-lauric acid content of 80% after the start side reaction diagram inflection point ; density of 0.9868 is the end of the reaction, then the α-chloro maximum content of lauric acid, chlorinated acid content of less than 1%, α, α-chloro-lauric acid not a lot of production. GC-RD coupling method simple equipment can be quickly and easily online monitoring of α-chloro depth of the reaction, the establishment of GC-RD coupling diagram after the determination of the actual production only relative density of the reaction system, coupled to the control GC-RD diagram, an indirect characterization of the content of α-CDA, control the reaction process, this method is expected for the reaction of α-chloro-line monitoring of industrialization. In this paper, a solvent-based synthesis of quaternary α-decyl betaine. The process avoids the aqueous phase reaction easy to generate α-hydroxy acid by-products, and other organic solvent phase reaction solvent was removed for further drawbacks, and further α-decyl betaine to improve the yield and product quality. In the preliminary investigation feeding mode, feed ratio, reaction temperature, reaction time, pre-cast NaOH factors such as solvent quaternization reaction effects, based on the design of orthogonal design feed ratio, reaction temperature, reaction time and other factors, solvent-derived quaternization reaction optimal reaction conditions were: α-chloro trimethylamine and lauric acid molar feed ratio of 6:1, the reaction temperature was 60 ℃, reaction time 10 h, under this condition, α-decyl betaine yield up to 92.4%. In the process of solvent-based quaternary ammonium, synthesis of myristic acid, palmitic acid, stearic acid derivative of α-dodecyl betaine, α-tetradecyl betaine, α-hexadecyl betaine, and its preliminary exploration process conditions.
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