ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A novel method for the investigation of the thermodynamic properties of free radicals is described. It involves the establishment of an equilibrium of the form \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm R}_1 {\rightleftharpoons} {\rm R + olefin} $$\end{document} where R1 and R2 are free radicals, and the measurement of the recombination products of R1 and R2. The method is applied to the case where R1 is n-propyl, R2 is methyl, and the olefin is ethene, using the thermal decomposition of azomethane (a source of methyl) in the presence of ethene in the temperature range of 581-649°K. Using the best available thermodynamic parameters for methyl, it is concluded that those for n-propyl are in need of adjustment. We recommend the values ΔHf°(300°K) = 22.6 ± 1 kcal/mol and S300° = 67.4 ± 3 cal/mol · K together with either the heat capacity data of O'Neal and Benson or the essentially identical data derivable from the results of Purnell and Quinn.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550090503
