Steric influence in the direction of elimination of gas-phase pyrolyses of several highly branched secondary acetates

✍ Scribed by Carolina Arcila; Maria Pino; Jacek Lubinkowski; Jose Adan Hernandez A; Gabriel Chuchani

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: English
• Weight: 457 KB
• Volume: 16
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550160108

✦ Synopsis

The rate coefficients for the gas-phase pyrolyses of a series of structurally related secondary acetates have been measured in a static system over the temperature range of 289.1-3595°C and the pressure range 50.0-203.0 torr. The temperature dependence of the rate coefficients is given by the following Arrhenius equations: for 3-hexyl acetate, log k l (s-l) = (12.12 f 0.33) -(176.1 f 3.9)kJlmo1/2.203RT; for 5-methyl-3-hexyl acetate, log k1 (s-l) = (13.17 f 0.20) -(186.2 f 2.3)kJlmo1/2.303RT; and for 5,5-dimethyl-3-hexyl acetate, log k l (s-l) = (12.70 f 0.19) -(177.4 f 2.2)kJ/mo1/2.303RT. The direction of elimination of these esters has shown from the invariability of olefin distributions a t different temperatures and percentages of decomposition that steric hindrance is a determining factor in the eclipsed cis conformation. Moreover, a more detailed analysis indicates that the greater the alkyl-alkyl interaction, the less favored the elimination tends to be. Otherwise, an increase of alkylhydrogen interaction caused steric acceleration to be the determining factor.