Theoretical studies of unimolecular reactions of C2–C5 alkoxyl radicals. Part III. A microscopic structure activity relationship (SAR)

Abstract

Theoretical investigations of reactivity trends of linear alkoxyl radicals up to pentoxyl have been performed. We make use of our formerly derived ab initio data (Part I: H. Somnitz and R. Zellner, Phys. Chem. Chem. Phys., 2000, 2, 1899) and the complete fall-off curves resulting from the subsequent RRKM/ME (master-equation) treatment (Part II: H. Somnitz and R. Zellner, Phys. Chem. Chem. Phys., 2000, 2, 1907). The correlation of the formerly derived G2(PMP2,SVP) energy barriers with the corresponding reactive transition states (TS), and hence the products of the reaction, yields a microscopic structure activity relationship which is capable of predicting energy barrier heights for the relevant decomposition pathways of linear alkoxyl radicals of arbitrary chain-length. The underlying principle of this SAR can also be applied to the corresponding isomerisation reactions. A comparison is made with SARs formerly derived in the literature.