Bis-pyrazole aza compounds, processes for making them, and hair dye compositions containing these compounds

A composition for dyeing hair containing at least one bis-pyrazole aza compound of the following formula (I):

• ##STR11## wherein R.sub.1, R.sub.1 ', R.sub.2, R.sub.2 ', R.sub.3 and R.sub.3 ' are each, independently of each other, H, a straight, branched or cyclic alkyl group having 1 to 6 carbon atoms, a straight chain or branched monohydroxy-alkyl group or polyhydroxyalkyl group with 1 to 6 carbon atoms, a straight or branched alkoxyalkyl group with 2 to 6 carbon atoms, a straight or branched monoaminoalkyl group or polyaminoalkyl group with 2 to 6 carbon atoms, or an unsubstituted aromatic or heteroaromatic ring, or a substituted aromatic or heteroaromatic ring having one or more halogen, a C.sub.1 - to C.sub.4 -alkyl group, a nitro group, a sulfonic acid group, a carboxylic acid group or a C.sub.1 - to C.sub.4 -alkoxy group substituent, or an unsubstituted benzyl group, or a benzyl group substituted with one or more halogen atoms, a hydroxy group, a C.sub.1 - to C.sub.4 -alkyl group, a nitro group or a C.sub.1 - to C.sub.4 -alkoxy group, or R.sub.1 together with R.sub.2 and/or R.sub.1 ' together with R.sub.2 ' represent a C.sub.3 - diradical bridge or a salt of an organic or inorganic acid thereof.

A process for making the bis-pyrazole aza compound of formula (I), said process comprising reacting a pyrazole of formula (Ia) and a pyrazole of formula (Ib):

• ##STR12## with an oxidizing agent in neutral or basic media;
• wherein R.sub.1, R.sub.1 ', R.sub.2, R.sub.2 ', R.sub.3 and R.sub.3 ' groups are each, independently of each other, H, a straight, branched or cyclic alkyl group having 1 to 6 carbon atoms, a straight chain or branched monohydroxyalkyl group or polyhydroxyalkyl group with 1 to 6 carbon atoms, a straight or branched alkoxyalkyl group with 2 to 6 carbon atoms, a straight or branched monoaminoalkyl group or polyaminoalkyl group with 2 to 6 carbon atoms, or an unsubstituted aromatic or heteroaromatic ring, or a substituted aromatic or heteroaromatic ring having one or more halogen, a C.sub.1 - to C.sub.4 -alkyl group, a nitro group, a sulfonic acid group, a carboxylic acid group or a C.sub.1 - to C.sub.4 -alkoxy group substituent, or an unsubstituted benzyl group, or a benzyl group substituted with one or more halogen atoms, a hydroxy group, a C.sub.1 - to C.sub.4 -alkyl group, a nitro group or a C.sub.1 - to C.sub.4 -alkoxy group, or
• R.sub.1 together with R.sub.2 and/or R.sub.1 ' together with R.sub.2 ' represent a C.sub.3 -diradical bridge or a salt of an organic or inorganic acid thereof.