prov:value
| - where R is an m valent aliphatic, cycloaliphatic heterocyclic or aromatic residue and each Y, which may be the same or different, is ##STR3## where R1 is, or, when n is more than 1, each R1, which may be the same or different, is an alkyl, alkenyl, aralkyl, N-substituted carbamyl, phenyl, NO2, halogen or ##STR4## group where R2 is a C1 -C4 alkyl group, n is 0, 1, 2 or 3
|