"up, R7 is a hydrogen atom, alkyl group having 1 to 15 carbon atoms, halogen atom, phenyl group, or derivative of phenyl group, and Z is a hydrogen atom, ammonium radical, or alkali metal atom, or by the general formula [III] ##STR4## wherein R8 and R9 are each a hydrogen atom, alkyl group having 1 to 15 carbon atoms, halogen atom, phenyl group, or derivative of phenyl group." . . . . .