Metal ligand containing bleaching compositions

A method of oxidizing lignin comprising contacting lignin in solution with a bleaching composition comprising:

• (a) an oxidatively stable activator having the structure ##STR10## wherein Y.sub.1, Y.sub.3 and Y.sub.4 each represent a bridging group having zero, one, two or three carbon containing nodes for substitution, and Y.sub.2 is a bridging group having at least one carbon containing node for substitution, each said node containing a C(R), C(R.sub.1)(R.sub.2), or a C(R).sub.2 unit and each R substituent is the same or different from the remaining R substituents and (i) is selected from the group consisting of alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, alkynyl, alkylaryl, halogen, alkoxy, phenoxy, CH.sub.2 CF.sub.3, CF.sub.3 and combinations thereof, or (ii) form a substituted or unsubstituted benzene ring of which two carbon atoms in the ring form nodes in the Y unit, or (iii) together with a paired R substituent bound to the same carbon atom form a cycloalkyl or cycloalkenyl ring, which may include at least one atom other than carbon;
• M is a transition metal with oxidation states of I, II, III, IV, V, VI, VII or VIII or selected from Groups 3, 4, 5, 6, 7, 8, 9, 10 and 11 of the Periodic Table of the Elements;
• and Q is any counterion which would balance the charge of the compound on a stoichiometric basis;
• and
• (b) an amount of a source of an oxidant effective for oxidizing lignin.

A method of bleaching lignin comprising contacting lignin with a bleaching composition comprising:

• (a) an oxidatively stable activator having the structure ##STR12## wherein Y.sub.1, Y.sub.3 and Y.sub.4 each represent a bridging group having zero, one, two or three carbon containing nodes for substitution, and Y.sub.2 is a bridging group having at least one carbon containing node for substitution, each said node containing a C(R), C(R.sub.1)(R.sub.2), or a C(R).sub.2 unit and each R substituent is the same or different from the remaining R substituents and (i) is selected from the group consisting of alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, alkynyl, alkylaryl, halogen, alkoxy, phenoxy, CH.sub.2 CF.sub.3, CF.sub.3 and combinations thereof, or (ii) form a substituted or unsubstituted benzene ring of which two carbon atoms in the ring form nodes in the Y unit, or (iii) together with a paired R substituent bound to the same carbon atom form a cycloalkyl or cycloalkenyl ring, which may include at least one atom other than carbon;
• M is a transition metal with oxidation states of I, II, III, IV, V, VI, VII or VIII or selected from Groups 3, 4, 5, 6, 7, 8, 9, 10 and 11 of the Periodic Table of the Elements;
• and Q is any counterion which would balance the charge of the compound on a stoichiometric basis;
• and
• (b) an amount of a source of an oxidant effective for bleaching lignin.