Abstract: Disclosed is a process for the preparation of a mixture of 4-bromophenyl derivatives (compound of formula (2)) and 2,4-dibromophenyl derivatives (compound of formula (3)) comprising the steps of [1] reacting in a two-phase (liquid-liquid) system a bromide containing source with a phenyl derivative (formula (1)) in the presence of an excess of an oxidizing agent, an acid, and optionally a catalyst selected from vanadium pentoxide and ammonium heptamolybdate forming 4-bromo- (compound of formula (2)) and 2,4-dibromo derivatives (compound of formula (3)) and as intermediate product the 2-bromo derivative (compound of formula (4)) which reacts in step [2] to the 2,4-dibromo derivative (formula (3)) according to the following reaction scheme 2 wherein R1 is hydroxy; C1-C5alkoxy; or —NR2R3; and R2 and R3 independently from each other are hydrogen; or C1-C5alkyl.

Abstract: Disclosed are thiol dyes of formula (1), wherein R1 is hydrogen; C1-C12alkyl; or phenyl-C1-C4alkyl; X is C1-C12alkylene; C2-C12alkenylene; C5-C10cycloalkylene; C5-C10arylene; or C5-C10arylene-C1-C10alkylene; Y is the residue of an organic dye which corresponds to the formula (1a), wherein R2 is hydrogen; or C1-C5alkyl; R3 is a radical of formula (1a1): (1a2); or (1a3); or R2 and R3 together with the linking carbon atom C form a 6 to 10 membered carbocyclic ring which may optionally be a condensated aromatic system and may contain one or more than one hetero atom; and R4, R5 and R6 independently form each other are hydrogen, or C1-C5alkyl; Z is H; or a thio ester group of formula (1b), wherein A is O; S; or N—R9; B is —OR7; —NR7R8, or —SR7; and A is O; S; or N—R9; B is —OR7; —NR7R8, or —SR7; and R7, R8 and R9, independently from each other are hydrogen; C1-C12alkyl C6-C12aryl; or C6-C12aryl-C1-C12alkyl. The compounds are useful for the dyeing of organic materials, such as keratin fibers, preferably human hair.