Synthesis Of Sodium N-lauroylglycinate By Modification Of The Schotten-baumann Reaction

With the depletion of oil resources,the development of green chemistry and increasing attention on the safety of chemicals, surfactants synthesized by petroleum materials are gradually replaced by deriving from renewable raw materials. Sodium N-fatty acyl amino acid(SFAAA) is an industrialized anionic surfactant, which was derived from natural fatty acids and industrial fermentation amino acids and has been widely applied in personal care and cleaning products due to its good surface activity and application performance, especially its low-toxicity, non-toxic and excellent biodegradability. However, the main synthesis method of N-fatty acyl amino acid sodium at present is via the traditional Schotten-Baumann reaction with fatty acyl chloride and amino acids as starting materials under the action of alkaline catalyst. However, the traditional Schotten-Baumann reaction uses non eco- friendly fatty acyl chloride and VOC and produces by-product of sodium chloride, the present of water in the aqueous solution leads to an increase of sodium fatty acid in the product. Therefore, to develop a new synthetic method by modification of the Schotten-Baumann reaction that is more in line with the principles of green chemistry has the double meaning of academic and application.Based on the above issues, a novel synthesis method by modification of the Schotten-Baumann reaction is developed to synthesize sodium N- lauroylglycinate(SLG) from methyl laurate(ML) and sodium glycinate(SG) catalyzed by sodium methoxide(SM) in glycerol and methanol. The relative research contents are shown as follows.The synthesize of SLG with ML and SG as raw materials is catalyzed by SM in polyol. Some affecting factors such as reaction solvent type, catalyst type, removal of methanol, molar ratio of SG to ML, the catalyst dosage of SM, reaction time and temperature on the condensation reaction are investigated, through orthogonal experiments to get the better experimental conditions. With glycerol as solvent and nitrogen bubbling for removing methanol, it is showed that the yield of SLG reaches 80.2% under the molar ratios of ML/SG/SM being 1.0 : 2.5 : 0.02 and catalyzed by SM for 3.5 h at 135 oC in glycerol, and glycerol monolaurate(GML) had been transformed completely.The synthesize of SLG with ML and SG as raw materials is catalyzed by SM in methanol and hydrothermal rector. Some affecting factors such as reaction solvent type, catalyst type, molar ratio of ML to SG, the catalyst dosage of SM, reaction time and temperature on the hydrothermal reaction are investigated under the using of hydrothermal reactor to increase the reaction temperature and the molar ratios of SG/ML being 5.0 : 1.0. It is showed that the yield of SLG reaches 62.4% under the molar ratios of SG/ML/SM being 5.0 : 1.0 : 0.01 and catalyzed by SM for 24 h at 125 oC in methanol. With an increase on the molar ratios of SG/ML to investigate the feasibility of the modificated reaction in a packed bed reactor, the influence of molar ratios of SG/ML on the hydrothermal reaction was investigated under the condition of the molar ratios of ML/SM being 1.0 : 0.01, for 24 h at 125 oC in methanol. It is showed that the yield of SLG was increased up to 93.6%. Based on the above research result, We found that this modificated reaction has the possibility to be carried out in a packed bed reactor, and it is an effective method to improve the yield of SLG by increasing the molar ratios of SG/ML.For designing the molecular of SFAAA, Sodium N- lauroylalanine(SLA) and Sodium N-lauroylsarcosinate(SLS) were synthesized by changing the types of sodium amino acid. It proved the universality of the modificated synthesis method. Surface activity, wetting time, foam ability and emulsifying ability were measured of SLA, SLS and SLG. We found that the types of amino acid sodium did not have a significant impact on the surface ability of SLA, SLS and SLG under the same lipophilic group, and SLS possess the best comprehensive ability.In a word, a novel synthesis method of the modificated of Schotten-Baumann reaction is developed to prepare SLG from ML and SG catalyzed by SM in glycerol and methanol and the appropriate reaction conditions are also explored. Compared with the traditional Schotten-Baumann reaction, firstly, the modificated method are eco- friendly and free from the bothersome by-product of sodium chloride; secondly, the use of glycerol which could be used as formulation components as an alternative to medium solvents such as acetone, gets rid of VOC and improves the environmental performance of the process and the quality of products; thirdly, the feasibility of the modificated reaction in a packed bed reactor is evaluated by simulating the reaction with increasing the reaction temperature by and hydrothermal reaction to strengthen the reaction conditions and the molar ratios of SG/ML, we found that it is an effective method to improve the yield of SLG under the hydrothermal condition and by increasing the molar ratios of SG/ML.