The invention relates to a preparation method of watermelon
ketone, which comprises the following steps: by taking 4-methylcatechol and 1,3-dichloroacetone as raw materials and
carbonate as a base catalyst, adding a
drying agent into a
Soxhlet extractor for
dehydration, and under the protection of
inert gas, assembling a reduced pressure
reflux water removal device to prepare a watermelon
ketone crude product; carrying out rotary
evaporation to recover a
solvent, carrying out post-treatment steps of decoloration, concentration and the like, and transferring an obtained solution into a rectification device provided with a glass vacuum rectification column to carry out segmented rectification: in first-stage rectification, evaporating off reaction
solvent light components, in second-stage rectification, collecting fractions to obtain a residual
raw material 4-methylcatechol and a part of crude product watermelon
ketone, and in third-stage rectification, collecting a main fraction watermelon ketone crude product; and recrystallizing the watermelon ketone crude product. According to the preparation method of the watermelon ketone, the yield of the watermelon ketone is improved through the reduced pressure
reflux water removal device, the watermelon ketone is purified step by step by combining segmented rectification and recrystallization, the purity of the product reaches 98% or above, the technological process is simplified, and the problem that industrial large-scale production is difficult to achieve through an existing watermelon
ketone synthesis technology is solved.