| A novel type of amphoteric surfactantsα-capric betaine (α-CB) was prepared through ammonolysis of long chain fatty acid derivativeα-chlorododecanoic acid (α-CDA) with trimethylamine. Many advantages of the synthesis were cheap raw material, simple synthesis route and good comprehensive product property. In this paper,α-CB prepared usingα-CDA was theoretically investigated. Through the simulation of production process, the technology ofα-CB prepared usingα-CDA was investigated. The qualitative and quantitative analysis method was developed to determineα-CB. An environmental and economic techonology route was chosen so as to provide basis for future amplification of ammonolysis reactor and industrial production practice. The main points were as follows:A method for the determination ofα-CB by high performance liquid chromatography coupled with evaporative light-scattering detection (HPLC-ELSD) was developed. According to the recovery experiment and the interference experiment, it was concluded that HPLC-ELSD was an accurate analysis method for analysisα-CB. Moreover, The traditional method of phosphotungstic acid titration to determineα-CB wasn't suitable. The reason was that trimethylamine had much influence on phosphotungstic acid titration. The method to determine residual fatty acids in reaction products was developed by two-phase titration with bromcresol green indicator and gas chromatography with area normalization method. The structure of target compoundα-CB was characterized by infrared spectrum, nuclear magnetic resonance, mass spectrometry, element analysis, etc.The participation effect of the neighboring carboxyl group ofα-CDA on dynamics and thermodynamics of the reaction was investigated. The experimental results indicate that the addition of NaOH is unfavorable to ammonolysis ofα-CDA due to the participation effect of neighboring carboxyl group ofα-CDA, which is contrary to the fact that strong alkaline environment is propitious to SN reactions of ordinary chlorinated hydrocarbons. On the one hand, the presence of NaOH results in the decline of charge density ofα-carbon atom inα-CDA and the decrease of ammonolysis rate, which accords with the calculated result by semi-empirical quantum chemistry calculation. On the other hand, NaOH accelerates the hydrolysis ofα-CDA to produce byproductα-hydroxyldodecanoic acid (α-HDA) and thus makes the equilibrium yield ofα-CB deceased. The fact that increasing solvent polarity increases the reaction rate supports to the conclusion that the ammonolysis ofα-CDA with trimethylamine follows SN2 mechanism.The effect of some process parameters such as the feed way of initial substances, the ratio of initial substances, concentration ofα-CDA, solvent and reaction temperature on ammonolysis ofα-CDA with trimethylamine was investigated. Optimization of process condition was approached. Through reaction temperature programmed, KI as catalyst, controlling PH, removing Cl ion, adding NaCl andα-CB added in advance, the yield ofα-CB was much improved and the yield of by-productα-HDA was decreased. The optimum conditions were obtained: KI as catalyst, m (α-CDA) / m (KI) =100, the aqueous solution with 15% ofα-CB mass fraction added in advance, aqueous solution as solvent, n(trimethylamine)/ n(α-CDA) = 3, c (α-CDA) = 1.70mol/L, reacted for 8 hours at 70℃, then reacted for 2 hours at 100℃. The yield ofα-CB reached 86.35%.Dodecyl betaine, tetradecyl betaine and hexadecyl betaine were successfully prepared byα-chloro-myristic acid,α-chloro-hexadecanoic acid andα-chloro-stearic acid respectively. The synthesis of dodecyl betaine, tetradecyl betaine and hexadecyl betaine were preliminary investigated respectively.
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