Method for preparing methylal using combined continuous distillation and liquid-liquid extraction

Abstract

The preparation technique combined continual reaction rectification and liquid-liquid extraction for methylal comprises: one-time adding the catalyst of toluenesulfonic acid and formaldehyde into reaction kettle as well as methanol from rectification column; controlling the temperatures of kettle and top of reaction rectification device within 50~55Deg and 35~42Deg respectively; then, with glycerin or bicarbinolamine as extractant, taking liquid-liquid extraction to the distillate from tower top with 92% methylal and 6% methanol and 2% water to obtain the methylal on tower top; recovering the extractant and methanol-water mixture for cycle. This invention has yield more than 97% with short reaction period and fast speed.

Description

technical field [0001] The invention relates to an organic chemical process, in particular to a method for preparing methylal by combining continuous reactive distillation and liquid-liquid extraction. Background technique [0002] The traditional methylal synthesis process adopts the following four methods: dichloromethane is the earliest method for synthesizing methylal. Due to backward technology and low yield, this method is not industrialized; dimethyl sulfoxide method, due to dimethyl sulfoxide Sulfone is unstable to acid, and formaldehyde will be generated when heated, so there is no industrialization; the calcium chloride method, the reaction yield can reach 86.5%, but due to the long reaction time and inconvenient post-treatment, so there is no industrialization; acid-catalyzed batch method, yield The production rate is relatively low, the production cycle is long, and the energy consumption is high, but the main way to produce methylal in my country, the content is a...

AI Technical Summary

Problems solved by technology

[0002] The traditional methylal synthesis process adopts the following four methods: dichloromethane is the earliest method for synthesizing methylal. Due to backward technology and low yield, this method has no industrialization; dimethyl sulfoxide method, due to dimethyl sulfoxide Sulfone is unstable to acid, and formaldehyde will be generated when heated, so there is no industrialization; the calcium chloride method, the reaction yield can reach 86.5%, but due to the long reaction time and inconvenient post-treatment, so there is no industrialization; acid-catalyzed batch method, yield The production rate is relatively low, the production cycle is long, and the energy consumption is high. However, the main way to produce methylal in my country, the content is about 55%, and it can reach about 99% after azeotropic distillation, drying and precision distillation. The energy consumption of the process is high, the process is more complex, and the by-products generated by drying are high in recycling costs

The shortcomings of the traditional process are the low purity of the reaction product, the complicated purification process, and the high cost of drying the by-products.

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