The invention relates to a thiodicarb synthesis method with high
methomyl conversion rate. The method comprises the following steps: adopting
xylene and
toluene as solvents; reaction: when the temperature in the synthesis kettle is reduced to be lower than 0 DEG C, starting to dropwise add SCl2, after the SCl2 is dropwise added, adding
methomyl into the synthesis kettle, introducing
nitrogen into the kettle, heating, and reacting; after the reaction is finished, centrifuging to obtain centrifugate and a centrifugal
filter cake; primary
water washing and filter pressing; carrying out secondary washing and
centrifugation; washing with
methanol, and centrifuging; and carrying out
vacuum drying on a
filter cake obtained by centrifuging the
methanol washing material to obtain a thiodicarb finished product. According to the synthesis method provided by the invention, when the intermediate thiobipyridine
hydrochloride is synthesized, a
toluene and
xylene double-component
solvent is adopted,
pyridine is used as a
raw material and a
solvent, and the reasonable material ratio avoids the influence on the reaction process of
pyridine and
sulfur dichloride due to overhigh
solid material concentration in a
reaction system; the yield of the thiobipyridine
hydrochloride and the conversion rate of
methomyl in the subsequent reaction between the thiobipyridine
hydrochloride and methomyl are improved.