The invention discloses a method for synthesizing
hexazinone through continuous
solvent-free reaction. The method comprises the following steps: preparing a
cyclic acid ester compound, synthesizing
hexazinone and purifying
hexazinone. According to the invention, N-ethylcarbonyl-N,N',N'-trimethylguanidine and cyclohexyl
isocyanate are subjected to a reaction according to a certain ratio (
molar ratio of 1:1) in a
static mixer A at normal temperature, a
mixed solution passes through a
static mixer B to generate hexazinone under the action of a catalyst
sodium methoxide, the generated hexazinone is subjected to
acid washing neutralization through a
static mixer, an organic phase enters a melt crystallizer, crystallizing is performed, and
slicing is performed after qualification, so that hexazinone with the content of more than 99% and the yield of about 95% can be obtained; and n-
hexane and
toluene solvents do not need to be added, so that the problem of
solvent volatilization does not need to be considered in the processes of neutralizing,
water washing, distilling and
drying of hexazinone, the production cost can be saved, and the problem that during
solvent crystallization, a part of hexazinone is taken away from the
mother liquor does not need to be considered so as to improve the yield.