NEW MATERIAL: The compound of formula I (Z is halogen).

EXAMPLE: 4-(β-chloroethylsulfonyl-metnyl)-benzoyl chloride.

USE: This is used as a fiber reactive compound, particularly, an intermediate needed for introducing a reactive group into a fiber in the production of fiber reactive dyes.

PREPARATION: The alkyl group of the compound of formula II (Y is halogen, alkoxy or OH) is chlorinated and converted into the compound of formula III, which is brought to react with 2-mercapto-ethanol in an aq. soln. to obtain the thioether compound of formula IV (wherein Y is alkoxy or OH). Then, in the case Y is alkoxy, it is converted into OH by hydrolysis, and after that, the compound is treated with an oxidizing agent to convert into the sulfonyl compound of formula V, which is then treated by a chlorinating agent to obtain the compound of formula I.