Catalytic olefination. Estimation of the reactivity of polyhaloalkanes

Abstract

Global electrophilicity indices and carbon-halogen bond energies of a wide series of halogen derivatives were calculated in terms of the density functional theory (DFT). The calculated values were used to estimate the reactivity of halogen derivatives under conditions of catalytic olefination. Reactions of N-unsubstituted hydrazones with polyhaloalkanes in the presence of CuCl afforded substituted alkenes. The relation between the structure of polyhaloalkanes and their reactivity was studied using the reaction with 4-chlorobenzaldehyde hydrazone as an example. It was found that increase in the global electrophilicity index and decrease in the C-Hlg bond energy are accompanied by increase in the "olefinating" power of halogen derivatives.

The catalytic olefination reaction of aldehydes and ketones with CBr3CF3

“…In accordance with our model of ''catalytic olefination activity'' [21], CBr 3 CF 3 should be a very active reagent for catalytic olefination (the most reactive of all fluorinated compounds which we have used earlier) and should to provide high yields of desired products with aldehydes and ketones. The high difference in steric volumes of CF 3 group and bromine atom permit us to hope for high stereoselectivity of reaction.…”

Friedel–Crafts Alkylation of Arenes with 2-Halogeno-2-CF3-styrenes under Superacidic Conditions. Access to Trifluoromethylated Ethanes and Ethenes

“…Initial 1-aryl-2-halogeno-3,3,3-trifluoro­propenes 1a – l were obtained by reaction of aryl aldehydes with 1,1,1-trifluoro-2,2,2-trihaloethanes. − To estimate the electronic properties of reaction intermediates, we performed DFT calculations (B3LYP) of cations A , B , derived from styrenes 1 (Table ). Charge distribution, contribution of atomic orbital into molecular orbital, and global electrophilicity indices ω were calculated. In “open form” cations A1 – A12 , atom C 1 bears a positive charge (0.02–0.12 e) and has a large LUMO contribution (25.9–48.1%) (Table ).…”

A novel method for the synthesis of dichloroalkenes

“…Later, 8 it was demonstrated that bromotri chloromethane is a more reactive alkenylating reagent than tetrachloromethane, even in the presence of a cata lyst (0.5 mol. % CuCl).…”