Abstract: The invention relates to new chromiferous complex dyestuffs of the general formula: ##STR1## in which R represents a hydrogen atom or a .beta.-hydroxyethyl group, A represents a hydrogen atom, a phenyl group or a phenyl group substituted by one or more halogen atoms or alkyl groups of low molecular weight, and the nucleus B may be substituted by one or more chlorine atoms.These complexes may be used for the coloration of the natural or synthetic polyamides or leather.

Abstract: The invention relates to the preparation of 1-phenyl-3-carbamoyl-5-pyrazolones of the formula: ##STR1## in which the two symbols R and R' may be the same or different and each represents a hydrogen atom, an alkyl radical or a substituted alkyl radical containing 1 to 4 carbon atoms.An aqueous paste of diethyl oxalacetate phenylhydrazone is heated at a temperature not greater than 85.degree. C. until the hydrazone is completely melted, and the aqueous phase is then removed and the remaining hydrazone is treated with 2 to 12 molar equivalents of a compound of the formula HNRR' at a temperature between 20.degree. and 100.degree. C. The formation of 1-phenyl-3-carboxy-5-pyrazolone is thus avoided.