The autoxidation of optically active 1-bromo-2-methylbutane

• Published in: Canadian journal of chemistry Vol. 55; no. 9; pp. 1463 - 1467
• Main Authors: Howard, J. A, Chenier, J. H. B, Holden, D. A
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.05.1977
• ISSN: 0008-4042; 1480-3291
• DOI: 10.1139/v77-205

(+)-1-Bromo-2-methylbutane undergoes autoxidation at 1 atm of oxygen and 30 °C to give, after reduction with triphenylphosphine, 1-bromo-2-methyl-2-butanol with a (+) to (−) enantiomer ratio of 1.9 ± 0.2. The optically active 1-bromo-2-methyl-2-butyl radical is, therefore, partially trapped by oxygen at this pressure before it has time to completely racemize. The half-life for racemization of the preferred conformation is approximately 2 × 10 −8 s −1 at 30 °C. At 100 atm of oxygen the yield of (+)-CH 3 CH 2 COH(CH 3 )CH 2 Br is >90% and the reaction appears to proceed with retention of configuration. A small percentage of (−)-1-bromo-2-methyl-2-butanol is, however, still produced, presumably by inversion of configuration.