Process for preparing 1,2-benzisothiazoline-3-one

A process for preparing 1,2-benzisothiazolin-3-one of formula (I),

• comprising the steps:
• (a) reaction of a 2-halobenzonitrile compound of formula (II):
• where
• X is chlorine or bromine;
• with a reaction mixture comprising:
• (i) alkali metal sulfide and/or alkali metal hydrogensulfide and
• (ii) an alkyl halide compound of formula (III):
• R1X (III),
• where
• R1 is selected from the group consisting of unsubstituted or at least monosubstituted C1-C10 alkyl, unsubstituted or at least monosubstituted C5-C14 aryl and unsubstituted or at least monosubstituted C7-C18 aralkyl, where the substituents are selected from the group consisting of F, Cl, Br, I, OH, NH2, C1-C8 alkyl and OR2,
• where
• R2 is hydrogen or C1-C4 alkyl;
• and X is a chlorine or bromine,
• to form an intermediate of formula (IV), where R1 is as defined above,
• (b) reaction of the intermediate of formula (IV) obtained in step (a) with a halogenating agent or an oxidizing agent and
• subsequent reaction of the 2-(alkylsulfoxy) benzonitrile with an acid to form the 1,2-benzisothiazolin-3-one and a halide compound of the general-formula (V) R1X (V), where:
• R1 is selected from the group consisting of unsubstituted or at least monosubstituted C1-C10 alkyl, unsubstituted or at least monosubstituted C5-C14 aryl and unsubstituted or at least monosubstituted C7-C18 aralkyl,
• where the substituents are selected from the group consisting of F, Cl, Br, I, OH, NH2, C1-C8 alkyl and OR2,
• where
• R2 is hydrogen or C1-C4 alkyl;
• and X is chlorine or bromine.