Abstract: The subject matter of the present invention is directed to a process for producing 4,5-diaminopyrazole derivatives of the general formula (I) ##STR1## where R.sub.1 and R.sub.2 independently designate hydrogen, a C.sub.1 - to C.sub.6 -alkyl radical or a C.sub.2 - to C.sub.4 -hydroxyalkyl radical, which can be used as dye precursors, for example for hair dyes, and to new pyrazole derivatives.When using the process according to the invention good yields of isomer-pure 4,5-diaminopyrazole derivatives of general formula (I) can be obtained.

Abstract: The oxidation hair dye composition consists of a combination of 0.01 to 10 percent by weight of one or more developer substances and 0.01 to 5 percent by weight of one or more coupler substances, and 0.01 to 2 percent by weight of one or more azo dye compounds of the formula I, A--N=N--B, wherein A is a p-aminophenyl group or a 3-pyridyl group and B is a 2,6-diamino-3-pyridyl group or a substituted 4-[N,N-bis-(2'-hydroxyethyl)amino]phenyl group of formula IV: ##STR1## wherein R is hydrogen, an alkyl group having from 1 to 6 carbon atoms, fluorine, chlorine, bromine or iodine; andone or more cosmetic additive selected from the group consisting of solvents, surfactants, antioxidants, thickeners, pH-adjusting compounds, hair care materials and additional dye components. The additional dye components can be 6-amino-2-methylphenol, 2-amino-5-methylphenol, triphenylmethane dye compounds and/or aromatic nitro dye compounds.