Relations Between Structure and Reactivity in Free‐Radical Chemistry

Abstract

An analysis of the relations between structure and reactivity in free-radical chemistry has shown that the usual interpretation of reactivities by means of the stability of the radicals involved is greatly simplified and often incorrect. The C-X bond energies of the alkanes and simple alkyl derivatives can be explained qualitatively by strain efects in the ground state on the basis of the VSEPR theory and nonbonding interactions. To be able to explain reactivities in free-radical chemistry, it is necessary to deduce injormation about the geometry of the transition states during free-radical formation from experimental measurements. The relations between structure and reactivity in freeradical chemistry are interpreted in terms of bond dissociation energies, as well as polar and sieric effects.

Homolytic Bond Dissociation Enthalpies of C–C and C–H Bonds in Highly Crowded Alkanes

“…12,13 Correlation between trend in C-C, C-H bond energies and steric effect has been firstly suggested by Eyring 14 in 1932. Later, Rüchardt [15][16][17] demonstrated the influence of substitutions on the strength of the carbon-carbon bond, and also emphasized polar and steric effect according to experimental data. Velevkin and Nölke 18 took steric repulsion into consideration, thus successfully used UV-irradiation with mercury in the gas phase to synthesize polycarbon hydrocarbons.…”

Electron Spin Resonance and Laser Flash Photolysis Study of Radical Addition to Vinyl Acrylate and Related Alkenes

“…The addition of radicals to alkenes in order to initiate polymerization is one of the most important reactions in polymer chemistry and in organic synthesis, and has been reviewed in a number of articles [1][2][3][4][5][6][7] and books. [8][9][10] Radical addition reactions have been an important area for research in free radical chemistry and in chemical kinetics.…”

Fundamentals of Organic Chemistry

“…10 These differences are clearly presented in the plot shown in Figure 3.1a, where BDEs relative to Me-X are plotted against increasing α-substitution of the R-X molecule. However, it has also been long recognized that the trend in R-X BDE is dependent on the nature of the X group.…”

“…We begin with what should be the next-larger aromatic annulene after benzene, namely [10]annulene. The first characterization of [10]annulene was reported by Masamune and coworkers 183 in 1971.…”

“…The first ab initio study of [10]annulene was the work of Schaefer and coworkers. 184 Eight different isomers of [10]annulene were optimized at MP2/DZP//HF/DZP.…”