Coumarin compounds

A compound, of formula Ia, ##SPC17##

• in which each of
• R.sub.5 and R.sub.6, which may be the same or different, signifies a hydrogen atom, an alkyl or allyl, radical or an alkyl radical substituted by a halogen atom, an alkoxy or cyano group, which alkyl radicals and alkoxy moieties in such radicals contain 1 to 4 carbon atoms with the proviso that when one of R.sub.5 and R.sub.6 signifies a hydrogen atom the other has a significance other than hydrogen,
• R.sub.7 signifies a radical of formula (a), (b), (c), (d), or (e) ##EQU3## or ##SPC18##
• in which
• R.sub.20 signifies SO.sub.3 M,
• R.sub.21 signifies a hydrogen chlorine or bromine atom, a alkyl, alkoxy, cyano, thiocyano, trifluoromethyl, alkoxycarbonyl, benzyloxy-carbonyl, alkylcarbonyloxy, alkylcarbonylamino, amino-sulphonyl, alkylamino-sulphonyl or dialkylamino-sulphonyl radical, which alkyl and alkoxy radicals or moieties in such radicals contain 1 to 4 carbon atoms, each of
• R.sub.22, r.sub.23 and R.sub.24, which may be the same or different, signifies a hydrogen, chlorine or bromine atom, a SO.sub.3 M, methyl, alkoxy, cyano, thiocyano, trifluoro-methyl, alkoxycarbonyl, benzyloxycarbonyl, alkyl-carbonyloxy, alkylcarbonyl-amino, aminosulphonyl or alkylaminosulphonyl radical, which alkyl and alkoxy radicals or moieties in such radicals contain 1 to 4 carbon atoms, with the proviso that each of radicals of formula (a) (b) (c) and (d) bear only one --SO.sub.3 M group and the radical of formula (d) bears not more than two substituents in addition to the --SO.sub.3 M group,
• R.sub.10 signifies hydrogen, amino-sulphonyl or --SO.sub.3 M,
• R.sub.11 signifies a hydrogen atom or --SO.sub.3 M with the proviso that the radical of formula (e) contains only one --SO.sub.3 M group,
• the atom of radical (a) to (e) marked *, being, in each case, bound to the carbon atom designated by the same mark in formula Ia, and
• M is hydrogen or an alkali metal.