Kinetics of 1,5-Hydrogen Migration in Alkyl Radical Reaction Class

Artur Ratkiewicz,Barbara Bankiewicz

doi:10.1021/jp208432z

Abstract

Kinetics of the 1,5-intramolecular hydrogen migration in the alkyl radicals reaction class has been studied using the reaction class transition state theory combined with the linear energy relationship (LER) and the barrier height grouping (BHG) approach. The high pressure limits of the rate constants for the reference reaction of 1-pentyl → 1-pentyl, calculated by the Canonical Variational Transition State Theory (CVT) with the Small Curvature Tunneling (SCT), are taken from the literature. Direct comparison with available experimental data indicates that the RC-TST/LER, where only reaction energy is needed, can predict rate constants for any reaction in this reaction class with excellent accuracy. Specifically for this reaction class, the RC-TST/LER method has less than 65% systematic errors in the predicted rate constants when compared to explicit rate calculations.

Highlights

Being the initial product from the radical attack on the alkanes, alkyl radicals are important intermediates in the decomposition of organic fuels
We describe how the reaction class transition state theory (RC-TST)/linear energy relationship (LER) factors for the 1,6-H migration in alkyl radicals are derived using the training reaction set, three error analyses are presented
As mentioned in the ‘‘Introduction’’ section, the RC-TST/LER correlations for the 1,6-H shift reaction family are needed to provide a complete picture of the internal H migrations in alkyl radicals

Summary

Introduction

Being the initial product from the radical attack on the alkanes, alkyl radicals are important intermediates in the decomposition of organic fuels. Reac Kinet Mech Cat (2013) 108:545–564 chemistry is largely governed by mutually competitive unimolecular reactions, namely intramolecular H atom migration and direct decomposition (beta scission) of the C–C bond For this reason, there has been considerable and growing interest in investigating both of these reaction families for a long time [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33]

Methods

Results

Conclusion