SYNTHESIS OF MANGANESE OXIDATION CATALYST

C6153 (L) A process is described for the preparation of a manganese complex catalyst having the formula: wherein Mn is manganese in a III or IV oxidation state; X is independently a coordinating or bridging species selected from the group: H2O, O22-, O2-, OH-, HO2-, SH-, S2, >SO, C1-, N3-, SCN-, N3-, RSO3-, NH2-, NR3 and RCOO-; R is a radical selected from the group H, alkyl aryl radicals, optionally substituted; and R1COO- is an alkyl or aryl radical, optionally substituted. L is an organic ligand containing at least two nitrogen atoms that coordinate with the Mn; z is an integer ranging from -4 to +4; Y is a monovalent or multivalent counterion leading to charge neutrality; and q is an integer from 1 to 4; the process comprising the steps of: (i) reacting, in an aqueous medium, a manganese (II) salt with the ligand L to form a manganese coordinated substance, a counterion salt M2Yq being present wherein M is selected from the group consisting of metals, ammonium and alkanolammonium ions; (ii) oxidising the manganese coordinated substance of step (i) with an oxidising agent; (iii) basifying a reaction mixture containing the oxidised manganese coordinated substance formed in step (ii) to a pH of at least 10.5; and C6153 (L) (iv) contacting the basified reaction mixture with a further oxidising agent to form the manganese complex catalyst.