High production of adamantane oxygenates in propionic acid using VO(acac)2 and Eu(OTf)3 with O2

VO(acac)2 with 1 atm O2 catalysed the oxidation of adamantane to adamantanone, adamantanols and its esters in propionic acid at 353–393 K. Propionic acid was a more suitable solvent for the oxidation than acetic, butyric, valeric, or hexanoic acids. The maximum yield of oxygenates was 65% (3300 TON) in 360 min. Adamantane solubilities and chemical stabilities of carboxylic acid were important for the oxidation; however, the coordination of carboxylic anions with the vanadium catalyst strongly affected the oxidation activity. The oxidation rate of adamantane was enhanced 3.8 times by the addition of the Eu(OTf)3 co-catalyst. The product selectivity for various oxidations of alkane and UV–vis spectroscopic studies of V species indicated that an active species was electrophilic vanadium peroxide species coordinated propionic anion and OTf.

Graphical abstractAdamantane was effectively oxidised to adamantane oxygenates and its esters in propionic acid using the V catalyst with 1 atm O2. The maximum yield of the sum of oxygenates was 1.04 M (65%, 3300 TON) in 6 h.Figure optionsDownload full-size imageDownload as PowerPoint slide