| Summary: | 碩士 === 國立中央大學 === 化學工程與材料工程研究所 === 97 === The preparation of sodium methoxide and the phase-transfer catalyzed methoxy substitution of dichloromethane were studied. The physical and chemical processes were considered to derive the overall production rate equation for methylal. The factors (the types and amounts of the solvents, the kinds and amounts of phase-transfer catalysts, the stirring speed and the reaction temperature) affecting the overall reaction rate and the product distributed were studied. The results can be explained with the overall rate equation.
Sodium methoxide was prepared as follows: methanol 1.2 mol, sodium hydroxide 1 mol and phase-transfer catalyst (BzBu3NCl) amounts of 10% methanol, reaction temperature 50℃and stirring speed 200 rpm. Reaction time about 8 hours, vacuum-filter and distillation in 100~150℃, we can recycle methanol and obtain pure sodium methoxide solid.
The dimethoxymethane was synthesized by method I and method II.
Method I: sodium methoxide 2 mol, dichloromethane 1 mol, solvent (THF) 0.6 mol and phase-transfer catalyst (BzBu3NCl) amounts of 10% sodium methoxide, reaction temperature 50℃and stirring speed 200 rpm. Reaction time about 30 hours, we can obtain about 90% dimethoxymethane.
Method II: methanol 2.2 mol, sodium hydroxide 3.2 mol, dichloromethane 1 mol, solvent (THF) 0.6 mol and phase-transfer catalyst (BzBu3NCl) amounts of 10% methanol, reaction temperature 50℃and stirring speed 200 rpm. Reaction time about 3 hours, we can obtain about 50% dimethoxymethane.
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