Analysis And Synthesis Of Alpha Alkyl Betaine Surfactants

Alpha alkyl betaine are a kind of natural oil-based betaine surfactants, which synthesisroute have two steps, chlorinate the fatty acids, downstream products of oil industry, andquaternize with trimethylamine (TMA). Such surfactants have many advantages, such as,excellent performance, the sources of the raw materials are extensive and cheap, and thesynthesis process is simple.At first, alpha capric bataine (CB) was synthesized using solventless process with thematerial of alpha chloro dodecanoic acid (CDA) and TMA. The structure of CB wascharacterized after purification. Established quantitative analysis methods to analyze the rawmaterial, the main and by-products of CB product. Based on the analysis methods above,studied the effect of solvent on the synthesis of CB, optimized the technological condition forthe synthesis of CB with water and ethanol as the reaction solvent, discussed the impact ofcatalysts of KI, alkali and urotropin on the yield of CB; For the technology of ethanol solventto synthesize CB, attempted to research the desalinization of the by-product trimethylaminehydrochloride (TMA·HCl) in crude product. In order to real-time and online monitor thereaction process of CB in industrial manufacture, studied the feasibility that bromocresolgreen two-phase titration method be used to rapid analyze the CB content in industry. Inaddition, DB, TB and HB were synthesized, using the optimal technological condition andanalysis methods of CB, scaned they with infrared spectroscopy after purification, and settedup quantitative analysis methods to analyze DB, TB and HB as well as there residual fattyacids.In scope of the experiment of this paper, main results and conclusions are as follows:CB was synthesized using solventless process, the structure of CB was confirmed byFT-IR, ESI-MS,1H-NMR and elemental analysis after purification, established the methodand procedure of HPLC-ELSD to analyze CB content, coexistence species of raw materialand by-products have non influence on the result of the analysis. Soxhlet Extraction-GasChromatography (SE-GC) can accuratly analyze the residual dodecanoic acid (DA), unreactedCDA and by-product alpha hydroxyl dodecanoic acid (HDA) in CB product.It has been proved that the synthesis reaction of CB is SN2nucleophilic substitutionreaction through theory and experiment two aspects, the higher the polarity of the solvent, thefaster the reaction. With water as the reaction solvent, the optimal technological condition tosynthesize CB is nTMA: nCDA=8:1, T=95℃, t=10h, in this condition the yield of CB is91.26%. With ethanol as the reaction solvent, the optimal technological condition tosynthesize CB is nTMA: nCDA=12:1，T=105℃，t=10h, in this condition the yield of CB is92.85%. The catalysts of KI, alkali and urotropin have no promoting effect on the yield of CBwhether use water or ethanol as the solvent to synthesize CB. The desalination rate of CBproduct in ethanol solvent is99.62%.In order to real-time and online monitor the reaction process of CB in industrialmanufacture, studied the feasibility that bromocresol green two-phase titration method beused to rapid analyze the CB content in industry, experiments showed that this method can quickly analyze the total amount of the residual fatty acids of CB product, coupled with theinitial mass of CDA, CB content can be got. This method has a good reproducibility inanalyzing fatty acids (RSD<0.8%), the recovery rate of DA and CDA close to100%, but therecovery rate of HDA have some deviation. If control the sample concentration of CB productin the range of5g·L-1, the relative deviation of the fatty acids between the measured valueand the accurate value will be less than5%.DB, TB and HB were synthesized, using the optimal technological condition of CB, andscaned they with infrared spectroscopy after purification. The results showed that themolecules of the betaine have amino acid inner salt structure. It has a good accuracy and highprecision that the method of HPLC-ELSD be used to analyze the content of DB, TB and HB.Method of SE-GC is fit for analyze the residual fatty acids of DB, TB and HB. OV-1701capillary column coupled with temperature programming is fruitful to separate and analyzethe fatty acids (methyl ester derivatives).