Abstract
Electron Spin Resonance (ESR) spectroscopy is the technique sine qua non for establishing the geometric and electronic structures of the free radicals participating in many organic reactions and syntheses. It also allows the mechanisms of the complex network of elementary reactions constituting the overall chemical change to be determined and the rate parameters of these reactions to be measured. Radicals can be classified into two main types - and π-radicals. -radicals, exemplified by phenyl, have their free electron orbital projecting out from a non-planar radical centre. They are usually more reactive than -radicals, exemplified by alkyl radicals in which the free electron resides in a carbon 2pz orbital perpendicular to the planar radical centre. Fluorine substitution results in a progressive change from a planer -methyl radical to a tetrahedral -trifluoromethyl radical. The regioselectivity and stereoselectivity of intermolecular and intramolecular free atom and radical additions to unsaturated systems are discussed in terms of optimal orbital overlap, steric and free valence effects as are group transfers and SH 1 and SH 2 homolytic substitution reactions. The unusual reactions of aluminium and gallium atoms with alkenes, alkynes 1,2 and 1,3 dienes and benzene are considered. Recent controversies concerning the Fenton reaction and the free radical mode of action of the new antimalarial drug Artemisinin are reviewed. The potential for applications of ESR in conjuction with spin traps in heterogeneous catalysis is outlined.
Call for Papers in Thematic Issues
Advances of Heterocyclic Chemistry with Pesticide Activity
Global food safety and security will continue to be a global concern for the next 50 years and beyond. Plant diseases have had a significant impact on food safety and security throughout the entire food chain, from primary production to consumption. While conventional chemical pesticides have been traditionally used for ...read more
Calculation design of covalent/metal organic framework based catalysts
This research area combines theoretical computation and screening with machine learning for the design of covalent/metal organic framework-based catalysts, bridging the disciplines of organic chemistry, physical chemistry, computational chemistry, materials science, and machine learning. It covers several critical aspects: designing and synthesizing organic catalysts for improved performance, applying computational methods ...read more
Carbohydrates conversion in biofuels and bioproducts
Biomass pretreatment, hydrolysis, and saccharification of carbohydrates, and sugars bioconversion in biofuels and bioproducts within a biorefinery framework. Carbohydrates derived from woody biomass, agricultural wastes, algae, sewage sludge, or any other lignocellulosic feedstock are included in this issue. Simulation, techno-economic analysis, and life cycle analysis of a biorefinery process are ...read more
Catalytic C-H bond activation as a tool for functionalization of heterocycles
The major topic is the functionalization of heterocycles through catalyzed C-H bond activation. The strategies based on C-H activation not only provide straightforward formation of C-C or C-X bonds but, more importantly, allow for the avoidance of pre-functionalization of one or two of the cross-coupling partners. The beneficial impact of ...read more
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