Oxidation of adamantane with O2 catalysed by VO(acac)2 and reactivity of active species in acetic acid

✍ Scribed by Hirokazu Kobayashi; Ichiro Yamanaka

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 504 KB
• Volume: 294
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/j.molcata.2008.08.002

✦ Synopsis

The oxidation of adamantane (470 mM) catalysed by VO(acac) 2 (0.5 mM) with 1 atm O 2 in acetic acid at 393 K was studied. The major product was 1-adamantanol, and minor ones were 2-adamantanol and 2-adamantanone. The selectivity for 1-adamantanol (3 • -selectivity) was almost constant at 75% under all oxidation conditions. The VO(acac) 2 catalyst functioned efficiently in the oxidation with a turnover number (TON) of 440 over 600 min. The oxidation rate of adamantane was enhanced by 5.5 times by the addition of CF 3 SO 3 H (2.2 mM) to acetic acid. Reactivities of various alkanes in the presence of VO(acac) 2 catalyst and product selectivities indicated the contribution of electrophilic active species in the oxidation. The rate-determining step was dissociation of the C-H bond of alkane by electrophilic active V species. The activity of the VO(acac) 2 catalyst is significantly different from the autoxidation promoter, Co(acac) 3 . A reaction scheme for the oxidation is proposed on the basis of the reactivities and UV-vis and ESR spectroscopic studies.