The invention discloses a preparation method of 3-(2,2,2-trimethylhydrazine)
propionate dihydrate, belonging to the technical field of
chemical synthesis. The method comprises the following steps: adding tert-
butyl acrylate into a three-neck flask with a mechanical stirring and
dropping funnel, dropwisely adding excessive 5-50%
unsymmetrical dimethylhydrazine, and distilling out 3-(2,2-
dimethylhydrazine)tert-butyl
propionate while depressurizing; dissolving the
distillation product in
ethanol, introducing or dropwisely adding excessive 5-30%
methylation reagent, and washing with cold
ethanol to obtain 3-(2,2,2-trimethylhydrazine)tert-butyl
propionate; dissolving the 3-(2,2,2-trimethylhydrazine)tert-butyl propionate in water, adding a small amount of acid, and heating under
reflux for 1-3 hours; depressurizing to remove water and acid; and adding
solvent and organic amines into the remainder, filtering, and recrystallizing the
solid with 95%
ethanol to obtain the target product. The invention converts the
alkaline hydrolysis in the prior art into acidic
hydrolysis and consumes less acid, and the acid can be removed by depressurized
distillation; and the
neutralization only needs a small amount of alkali, and the salt generated after
neutralization can be dissolved in the
solvent so as to be removed, so that the purity of the obtained product is high.