title: TEMPO/HCl/NaNO2 catalyst: a transition-metal-free approach to efficient aerobic oxidation of alcohols to aldehydes and ketones under mild conditions.
abstract: Hydrochloric acid, a very inexpensive and readily available inorganic acid, has been found to cooperate exquisitely with NaNO(2)/TEMPO in catalyzing the molecular-oxygen-driven oxidation of a broad range of alcohol substrates to the corresponding aldehydes and ketones. This transition-metal-free catalytic oxidative conversion is novel and represents an interesting alternative route to the corresponding carbonyl compounds to the metal-catalyzed aerobic oxidation of alcohols. The reaction is highly selective with respect to the desired product when carried out at room temperature in air at atmospheric pressure. Notably, the use of very inexpensive NaNO(2) and HCl in combination with TEMPO for this highly selective aerobic oxidation of alcohols in air at ambient temperature makes the reaction operationally and economically very attractive. The results of mechanistic studies, performed with the aid of electrospray ionization mass spectrometry (ESI-MS), are presented and discussed. TEMPO, TEMPOH, and TEMPO(+) were observed in the redox cycle by means of ESI-MS. On the basis of these observations, a mechanism is proposed that may provide an insight into the newly developed aerobic alcohol oxidation.
authors.affiliation: Dalian Institute of Chemical Physics, Institution Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, PR China.
authors.forename: Xinliang
authors.initials: X
authors.lastname: Wang
authors.forename: Renhua
authors.initials: R
authors.lastname: Liu
authors.forename: Yu
authors.initials: Y
authors.lastname: Jin
authors.forename: Xinmiao
authors.initials: X
authors.lastname: Liang
mesh_terms: D000438:Alcohols / Q000737:chemistry*; D000447:Aldehydes / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003497:Cyclic N-Oxides / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry*; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D012977:Sodium Nitrite / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
chemical_list: D000438:Alcohols; D000447:Aldehydes; D003497:Cyclic N-Oxides; D007659:Ketones; D012977:Sodium Nitrite; D006851:Hydrochloric Acid; D010100:Oxygen; C003959:TEMPO