Semi-stoichiometric oxidation of benzylic alcohols to benzaldehydes was readily achieved in heated toluene in the presence of cobalt-doped birnessite MnO 2 under oxygen atmosphere. The oxidation took place selectively for benzylic alcohols, while allylic alcohols were oxidized slowly. No oxidation occurred for usual primary and secondary alcohols. Oxygen atmosphere was important to perform effective oxidation; i.e. the oxidation progressed much slower in nitrogen atmosphere. Cobalt-doped birnessite was the best catalyst for the oxidation, in which the amount of birnessite was reduced to 0.7 equivalent of alcohol, resulting in yields of aldehydes greater than 80%. The present method provides a useful green oxidation for benzylic alcohols.

Cathodic reduction of aqueous MnO 4− ions in the presence of various alkaline metals except for Na + ions led to the deposition of birnessite-type layered MnO 2 . The highest crystallinity was obtained when electrolyzed in a 2 mM KMnO 4 and 50 mM KCl at a constant potential of 0 V vs Ag/AgCl. The cathodic formation of MnO 2 was prevented by the presence of divalent cations, and Na + ions gave rise to an amorphous or low crystalline product. The birnessite film thus formed exhibited an excellent pseudocapacitive behavior in the as-deposited state, with a specific capacitance as high as 322 F g −1 at a scan rate of 2 mV s −1 , which is much larger than that (75 F g −1 ) of the birnessite film grown anodically. The resulting pseudocapacitive electrode functioned as an efficient catalyst toward the oxidation of L-cysteine, where the anodic overpotential was reduced by 0.15 to 0.3 V.

Atmosphere. -The title reaction takes place selectively with benzylic alcohols (I), whereas allylic alcohols such as (III) are oxidized quite slowly. No oxidation or poor yields are found in the oxidation of usual primary and secondary alcohols. Oxygen atmosphere is required to perform effective transformation, i.e. the oxidation progress is much slower in nitrogen atmosphere. -(KAMIMURA*, A.; NOZAKI, Y.; NISHIYAMA, M.; NAKAYAMA, M.; RSC Adv. 3 (2013) 2, 468-472, http://dx.doi.org/10.1039/c2ra22117a ; Dep. Appl. Mol. Biosci., Grad. Sch. Med., Yamaguchi Univ., Ube, Yamaguchi 755, Japan; Eng.) -S. Karsten 21-034