Theoretical studies of unimolecular reactions of C-2-C-5 alkoxyl radicals.Part III. A microscopic structure activity relationship (SAR)

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., 20 00, 2, 1899) and the complete fall-off curves resulting from the subsequent RRKM/ME (master-equation) treatment (Part II: H. Somnitz and R. Zellner, P hys. Chem. Chem. Phys., 2000, 2, 1907). The correlation of the formerly der ived G2(PMP2,SVP) energy barriers with the corresponding reactive transitio n states (TS), and hence the products of the reaction, yields a microscopic structure activity relationship which is capable of predicting energy barr ier heights for the relevant decomposition pathways of linear alkoxyl radic als of arbitrary chain-length. The underlying principle of this SAR can als o be applied to the corresponding isomerisation reactions. A comparison is made with SARs formerly derived in the literature.