Method for producing isothiocyanate compound
The object of the present invention is to provide a novel method for producing an isothiocyanate compound having a carboxyl group(s) by a reaction of the corresponding amino compound having a carboxyl group(s), thiocarbonyldiimidazole and a base, in one step with high purity. An amino compound having a carboxyl group(s) is reacted with thiocarbonyldiimidazole in a solvent in the presence of a base to obtain an isothiocyanate compound having a carboxyl group(s).
1. A method for producing an isothiocyanate compound comprising a carboxyl group, the isothiocyanate compound represented by formula (2):
(SCN) m -A-B—(CO 2 H) n (2)
wherein m, n, A and B are, respectively, as defined for formula (1),
the method comprising reacting (i) an amino compound comprising a carboxyl group, the amino compound represented by formula (1):
(H 2 N) m -A-B—(CO 2 H) n (1)
wherein
m and n, each are an integer of 1,
A is a phenylene group that is unsubstituted or substituted with one or more halogen atoms or one or more nitro groups, and
B is a single bond,
with (ii) thiocarbonyldiimidazole in a solvent in the presence of a base; followed by treating with acid and at least one poor solvent selected from the group consisting of water, a C 5-8 alkane, diethyl ether and diisopropylether;
then filtering said isothiocyanate compound.
2. The method of claim 1 , wherein the base is a tertiary amine.
3. The method of claim 2 , wherein the base is a tri C 1-6 alkylamine.
4. The method of claim 3 , wherein the base is triethylamine.
5. The method of claim 1 , wherein the solvent is a halogenated hydrocarbon.
6. The method of claim 5 , wherein the solvent is methylene chloride.
7. The method of claim 1 , wherein the acid is an acidic aqueous solution.
8. The method of claim 7 , wherein the acidic aqueous solution is hydrochloric acid.
9. The method of claim 1 , wherein the poor solvent is water or a C 5-8 alkane.