Preparation method of diethyl malonate

Abstract

The invention discloses a preparation method of diethyl malonate. The preparation method comprises the following steps: allowing a neutralization reaction between chloroacetic acid and soda solution, mixing an obtained product sodium monochloroacetate solution with sodium cyanide aqueous solution to allow a cyanation reaction while stirring to generate sodium cyanoacetate solution, mixing the sodium cyanoacetate solution with hydrochloride solution to allow an acidizing reaction while stirring to generate cyanoacetic acid solution, dehydrating the obtained cyanoacetic acid solution in a reaction kettle in vacuum, relieving vacuum, sequentially adding ethanol and a solid catalyst 12-tungstophosphoric acid, introducing HCL gas, stirring, keeping temperature and allowing a reflux reaction, cooling to 50 DEG C, continuously putting feed liquid in a filtration tank for filtration to obtain raw ester, then regulating PH of the raw ester value to be neutral, and turning to a rectification process to obtain the diethyl malonate finished product. Compared with the traditional process, the preparation method has lower cost and environment-friendly process and ensures balanced reaction and easy operation.

Description

technical field [0001] The invention relates to a method for preparing organic acid esters, in particular to a method for preparing diethyl malonate. Background technique [0002] The production of diethyl malonate has all adopted a traditional production process in China before, that is, the cyanoacetic acid generated in the process and ethanol are synthesized under the catalysis of 98% concentrated sulfuric acid. The main process and raw materials used include: [0003] 1, neutralization reaction process: raw material is the chloroacetic acid (molecular formula ClCH of 320Kg97%) 2 COOH), 180Kg99% sodium carbonate (Na 2 CO 3 ). Dissolve 180Kg of 99% sodium carbonate with hot water into a saturated solution of about 34%, and then use it to drop 320Kg of 97% chloroacetic acid weighed in the reactor, stir to make acid-base neutralization reaction occur, and control the end point pH value Equal to 7.0. The reaction product sodium chloroacetate solution was obtained. Reac...

AI Technical Summary

Problems solved by technology

[0013] The most prominent disadvantage of the traditional production process is that sulfuric acid is used as a catalyst in the esterification process to generate a large amount of acidic wastewater, which causes environmental pollution or brings relatively large environmental protection pressure and increases treatment costs.

And in the process of esterification, a large amount of waste gas hydrogen chloride is produced, which corrodes the equipment