disclosed and claimed are oxidation reactions involving , as a catalyst , a bis - and / or tris -- dimanganese complex salt of the formula i . sub . a . sub . b mnl ]. sup . x a . sub . y ac is a c 2 - c 8 - acyl group , a is 1 , 2 or 3 , b is 0 when a is 2 or 3 or b is 2 when a is 1 , x indicates the number of positive charges and is 2 or 3 , a is a singly or doubly negatively charged anion , y is the number of anions a required to balance the positive charges and l is a ligand , such as n , n - bis - n - methylamine or n , n , n &# 39 ;, n &# 39 ;- tetrakis - n - methylamine or n 1 n 1 n 1 , n 1 - tetrakis - 1 , 2 - ethylenediamine .