Theoretical study on the pyrolysis mechanism and kinetics of β-hydroxyketones

✍ Scribed by Wenlin Feng; Yan Wang; Shaowen Zhang

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 150 KB
• Volume: 62
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1997)62:3<297::aid-qua8>3.0.co;2-r

✦ Synopsis

The mechanism and kinetics for the decomposition of ␤-hydroxypropaldehyde, primary and secondary ␤-hydroxyketones, were studied by using ab initio RHFr6-31G and RHFr6-31G* methods. The activation barriers of these reactions were refined to be 39.57, 40.10, and 36.80 kcal mol y1 at the MP2rrRHFr6-31G* level, respectively. The calculated results show that each decomposition is a concerted process with hydrogen transferring and bond breaking via a six-membered cyclic transition state. The thermal rate constants of the decomposition of primary and secondary ␤-hydroxyketones were obtained by calculating microcanonical probability fluxes through each transition state. It is theoretically confirmed that methyl substitution at the hydroxyl carbon of ␤hydroxyketones causes a small enhancement in rates. The theoretical investigations of the mechanism and the rate constants are in agreement with the experimental results.