Continuous Synthesis And Properties Of Long-chain Quaternary Ammonium Hydroxides

Long-chain alkyl quaternary ammonium hydroxides are cationic surfactant which have surface activity and strong alkalinity,widely used in organic synthesis,catalyst synthesis and semiconductor industry.The alkyl quaternary ammonium hydroxides?QAHs?are commonly prepared by the counterions of quaternary ammonium salts that contains Cl^-?Br^-and CH₃SO₄^-.In the electrolysis process,halogen gas and strongly acidic substances can be produced,which can lead to environmental pollution and corrosion of electrolysis equipments.In addition,the preparation process of QAHs is discontinuity method in which the concentration of electrolyte fluctuates stronger so the life of membrane can be affected.To break this bottleneck,dimethyl carbonate was selected to be the alkyl agent for preparing the intermediate compounds instead of halogenated hydrocarbon and dimethyl sulfate.Various single-chain,double-chain and mixed carbon chain QAHs have been prepared by the continuous electrolysis method.Synthetic process,electrolysis technology,physical-chenical properties and application performance of the prepared QAHs were investigated.Alkyltrimethylammonium methylcarbonate,electrolytic reaction material,was synthesized by the hydrolysis of quaternary ammonium salts methyl carbonate,which was produced through reaction of long-chain alkyl tertiary amines and dimethyl carbonate?DMC?with methanol being solvent.Based on the electrolytic bath used in the discontinuous ion membrane electrolysis,anolyte and catholyte of the electrolysis reaction form a circulation loop respectively by adding anode liquid storage tank,circulating pump and deionized water chamber.The continuous production of electrolysis systems can be taken by adding alkyltrimethylammonium methylcarbonate with high concentration,deionized water and discharge continuously.Tetradecyltrimethylammonium hydroxide taken as an example,effects of the electrolysis reaction temperature,current density,the concentration of anolyte and the discharging concentration of catholyte on the current efficiency of electrolysis reaction were investigated by single-method experiment.The optimized condition was:reaction temperature 65?,current density 450 A/m²,the concentration of anolyte 1.40 mol/L,the discharging concentration of catholyte 0.15 mol/L.Under the optimized conditions,the electrolytic reaction have higher current efficiency,faster reaction rate and lower energy consumption with the current efficiency reaching 67.41%.The structure of the products were characterized by¹H-NMR and IR,which showed that tetradecyltrimethylammoniumhydroxideweresynthesizedsuccessfully.In addition,the results of the electrolysis technology research on QAHs with different long-chain showed that increasing the length of long-chain resulted in lower current efficiency,slower reaction rate and higher energy consumption in the reaction.Surface activity,alkalinity,wetting ability,foaming ability,clearing power and heavy metal content of decyltrimethylammonium hydroxide?DeTAH?,dodecyltrimethylammonium hydroxide?DTAH?,tetradecyltrimethylammonium hydroxide?TTAH?and cetyltrimethyl ammonium hydroxide?CeTAH?were determined.The results revealed that the four long-chain QAHs prepared by continuous ion membrane electrolysis had good surface activity and low heavy metal content with better clearing power than short-chain QAHs and Traditional inorganic base.In addition,with the increasing of the long-chain of QAHs,the critical micelle concentration?CMC?,alkalinity,wetting and foaming ability decreased.To further improve the application performance of long-chain QAHs,the performance of surface activity,wetting,foaming,emulsification ability and stability of the complex system of DTAH and APG-0810 were investigated.The results indicated that the complex system had good stability.The system performed better than either single component and gained lower CMC and in surface tension.The wetting ability,emulsifying aibility,foaming ability and clearing power were better than DTAH.