GB1131780A - Process for the preparation of o,o'-dihalogen-substituted aromatic isothiocyanates - Google Patents

Abstract

1,131,780. Halogen-substituted aromatic isothiocyanates. FARBENFABRIKEN BAYER A.G. 22 Sept., 1967 [22 Sept., 1966; 15 Oct., 1966; 31 Dec., 1966], No. 43227/67. Heading C2C. The invention comprises isothiocyanates of the general formula in which R<SP>2</SP> and R<SP>4</SP> represent hydrogen, chlorine or bromine atoms or NH 2 groups, and R<SP>1</SP> and R<SP>5</SP> both represent chlorine atoms and R<SP>3</SP> represents a bromine atom or a nitro, cyano, amino, - SO 2 -CH 3 , C 1 -C 4 alkyl, C 1 -C 4 alkoxy or C 1 -C 4 alkylthio group; or R<SP>1</SP> represents a bromine atom, R<SP>5</SP> represents a chlorine or a bromine atom and R<SP>3</SP> represents a hydrogen, chlorine or bromine atom or a nitro, cyano, amino, -SO 2 -CH 3 , C 1 -C 4 alkyl, C 1 -C 4 alkoxy or a C 1 -C 4 alkylthio group. These and other halogen-substituted aromatic isothiocyanates may be prepared by reacting an o,o<SP>1</SP>-dihalogenated primary aromatic amine with thiophosgene at a temperature in the range 50- 300‹ C. in an anhydrous inert organic solvent and optionally in the presence of a basic organic catalyst. Suitable solvents are, for example, aliphatic and aromatic hydrocarbons which may be halogenated. Suitable basic organic catalysts are, for example, alkyl-substituted acid amides such as dimethyl formamide, methyl formamide, dimethyl acetamide, tetramethyl urea, N-methyl pyrrolidone; amidines such as N,N-dimethyl-N<SP>1</SP>-phenylformadine; and tertiary amines such as dimethylbenzylamine and N-methylmorpholine.