Patent ID: 11897838
Assignee: JC (WUXI) COMPANY, INC.
Field: Organic fine chemistry (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A method for preparing an isothiocyanate compound of formula (I),

A-N═C═S  (I)

in formula I:
—N═C═S is isothiocyanate group;
A is —XR1 or —CR2R3R4, wherein
X is —(CH2)n—, and n is an integer of 0-6;
R1 is selected from the group consisting of methyl, tert-butyl, isopropyl, methylthio, methoxy, allyl, methallyl, cyclohexyl, methylsulfinyl, naphthyl, methyl cyclohexyl, morpholinyl, diethylamino, benzoyl, ethoxycarbonyl, tert-octyl, chlorine, trimethylsilyl, substituted or unsubstituted phenyl;
wherein, one or more hydrogen in the substituted phenyl are substituted by substituents selected from the following group: halogen, methyl, bromomethyl, ethyl, methoxy, nitro, azido, trifluoromethyl, difluoromethoxy, methylthio, cyano, trifluoromethoxy, trifluoromethylthio, tert-butoxycarbonyl, and ethoxycarbonyl;
R2, R3, and R4 are each independently H, phenyl or C1-3 alkyl;

wherein the method comprises:
(1) reacting, in the presence of an organic base, A-NH2 with CS2 in organic solvent so as to obtain a first reaction mixture containing dithiocarbamate,
wherein the organic solvent is an ethyl acetate, and ratio of the A-NH2 to the CS2 is 1:1.05-2;

(2) adding, in the presence of an optional base catalyst, a desulfurizing agent to the first reaction mixture to carry out a desulfurization reaction so as to obtain a second reaction mixture containing the isothiocyanate compound of formula (I),
wherein the desulfurizing agent is selected from the group consisting of methyl chloroformate, p-toluenesulfonyl chloride, solid phosgene, elemental iodine, chlorosilane, chlorophosphate, dicyclohexylcarbodiimide, dicyandiamide, triphenylphosphine, di-tert-butyl dicarbonate, cyanuric chloride, or combinations thereof;

(3) purifying the second reaction mixture by post-processing to obtain the isothiocyanate compound of formula (I); wherein in (3), the post-processing comprises:
washing the second reaction mixture and concentrating so as to obtain an acid-washed crude product;
distilling the acid-washed crude product so as to obtain a distilled crude product containing the isothiocyanate compound of formula (I); and
subjecting the distilled crude product to rectification under vacuum so as to obtain a pure isothiocyanate compound of formula (I).