The invention discloses a watermelon
ketone preparation method which comprises the following steps: (1) under an alkali condition and in the presence of aids, heating 4-methyl-orthodioxybenzene and
alcohol-protected ketalized 1,3-bisubstited
acetone to 30-120 DEG C in a
solvent, and performing a Williamson
ether synthesis reaction so as to generate a corresponding ketal intermittent, wherein reaction materials are fed in the following sequence: firstly, adding the
solvent, an alkali and aids, uniformly stirring, heating to a set temperature, slowly dropping 4-methyl-orthodioxybenzene and
alcohol-protected ketalized 1,3-bisubstited
acetone, and performing a reaction for 2-12 hours after dropping is competed; (2) performing a
backflow reaction on the ketal intermittent obtained in the step (1) for a certain time under an acid condition, pouring into water to implement
hydrolysis, extracting with ethyl
ether, washing an organic phase with a
sodium bicarbonate solution,
drying sodium sulfate, evaporating off the
solvent, and performing recrystallization, thereby obtaining watermelon
ketone. The method disclosed by the invention is easy to control, simple to operate, good in environmentprotection, relatively high in yield and beneficial to industrialization.