C2-IIH5OH + K2MnVIO4 C-IIIH3CIHO + MnIVO2 + 2 KOH

This is an oxidation-reduction (redox) reaction:

MnVI + 2 e- MnIV (reduction)

C-II - 3 e- CI (oxidation)

C-II + e- C-III (reduction)

Change the oxidation states