Reactions of the iso-butyl radical during 1,1′-azoisobutane pyrolysis

✍ Scribed by G. McKay; J. M. C. Turner

• Book ID: 102928636
• Publisher: John Wiley and Sons
• Year: 1978
• Tongue: English
• Weight: 559 KB
• Volume: 10
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550100107

✦ Synopsis

Quantitative analysis of the products formed in 1,l'-azoisobutane pyrolyses in the temperature range of 553"-602"K has shown that the major reactions of the iso-butyl radical are kc 2iC4H9 -2,5 dimethyl hexane and k4 (4) iC4H9 -CH3 + C3H6 Analysis of initial rate data gave loglo k~/(kc)1~2(~m-3~2~m~11~2~sec~1~2) = 7.54 f 0.44 -(136.5 f 4.8) kJ/mo1/2.303RT, the Arrhenius parameters obtained being in good agreement with thermodynamic data for reaction (4). Measured values of ka/(kC)'/* where k , is the rate constant of the reaction iC4Hg + AIB -iC4H10 + .AIB were consistent with published parameters determined by photolysis of 1,l'-azoisobutane. Combination of photolysis and pyrolysis data gave loglo k./(k.)'/2(cm3~2-moI-1~2-sec-1~2) = 3.68 i 0.15 -(27.2 f 1.2) kJ/ mo1/2.303RT. The crosscombination ratio for methyl and iso-hutyl radicals has been found to be 0.25, indicating that the geometric mean rule does not hold for methyl and iso-butyl radicals.