Kinetics and mechanism of oxidation of aliphatic alcohols by oxo(salen) manganese(V) complexes

654-659The oxidation of aliphatic alcohols by substituted oxo(salen)manganese(V) (H2salen = N,N'- Bissalicylideneethylenediamine) complexes, in acetonitrile, leads to the formation of the corresponding carbonyl compounds. The reaction is first order each in alcohol and Mn(V) complex. The oxidation of (1,1-2H2]ethanol and (2-2H]propan-2-ol exhibits substantial kinetic isotope effects. The rate of oxidation of twelve alcohols by four Mn(V) complexes have been determined. The oxidation is susceptible to both the polar and steric effects of the substituent in the alcohol molecule. The reaction constants are negative. The rate of reduction of the substituted Mn(V) complexes shows an excellent correlation in terms of Hammett equation with positive reaction constants. The reactivity-selectivity principle (RSP) is obeyed in this reaction. The validity of RSP is verified by Exner's mathematical procedure. Suitable mechanisms have been discussed