Study On The Synthesis Of Tetramethy Lammonium Hydroxide

With the increasing development of large scale integration circuits, the demand of high purity electronic grade tetramethylammonium hydroxide (TMAH) is increasing. The traditional preparation method of TMAH cost high and impurity ions is also high. Comprehensive comparative literature, this paper used dimethyl carbonate and trimethylamine methanol solution as raw material by synthesis,hydrolysis and electrolytic to prepare high purity TMAH.By single factor experiments and orthogonal test, the influences of the molar ratio of raw materials, reaction time, reaction temperature and reaction pressure on the conversion rate were studied. The experimental result shows that the optimum conditions were as follows:the molar ratio of dimethyl carbonate and trimethylamine was 1:1.2, reaction temperature was 115℃, reaction time was 5.5h and reaction pressure was 2MPa. The conversion rate can be up to 99.06% under the optimum condition.Tetramethylammonium methylcarbona hydrolysis process conditions were studied by single factor experiments. The molar ratio of water and tetramethylammonium methylcarbona was 6:1, at 70℃vacuum distill 2h, the conversion rate was 94.4%.Using Ti supported ruthenium dioxide as anode and stainless steel as cathode, the electrolytic synthesis of TMAH in an H type of electrolytic cell under a constant current density was studied. The effects of ion exchange membrane, concentration of tetramethylammonium hydrocarbonate, temperature of electrolyte and current density on the current efficiency of the process for synthesis were mainly investigated. The current efficiency was up to 83.5% at optimal operating condition:Aciples-F4403D cation exchange membrane, concentration of tetramethylammonium hydrocarbonate 1.41mol/L, electrolyte temperature 40～60℃, current density 792A/m2.The product of TMAH and tetramethylammonium hydrocarbonate was qualitative identified by the way of infared (IR) spectrum and nuclear magnetic resonance (NMR).