Effect of substituents in the ring on the structure and electron density distribution in benzyl halides

Abstract

The results of calculations for benzyl chlorides and benzyl bromides that contain substituents in the ring by different quantum-chemical methods are compared. The electron density on the benzyl carbon atom increases as the electron-withdrawing properties of substituents are enhanced due to the shi/~ of the electron density from the benzyl halogen atom to the adjacent carbon atom. A topological analysis according to Bader confirmed the main reason for the change in the paramagnetic shielding of the benzyl 13C nuclei. The results of calculations provide, for the first time, an explanation for the resonance upfietd 13C shift of this atom as the Harnmett constant of a substituent increases in compounds of the series under consideration.

Substituent effects on SN2 reaction between substituted benzyl chloride and chloride ion in gas phase

“…The effect of substituents on the structures, properties, and reactivities of S N 2 reactions has been of major interest in organic chemistry 9–20. The correlation between structure and reactivity forms the basis for much of our understanding of basic chemical principles; its use as a tool to probe the properties of transition states (TSs) and intermediates can be traced back to the beginnings of modern reaction chemistry 21.…”