Optimized Structures and Theoretical ¹H-NMR Spectral Analysis of the Methylene Protons in Dibenzyl Sulfoxide

Abstract

Dibenzyl sulfoxide [C6H5CH2)2SO, DBzSO] has been studied using density functional theory (DFT) methods with a particular emphasis on the theoretical 1H-NMR spectra of the methylene protons. The 1H-NMR chemical shifts of the methylene protons of DBzSO can be divided into two main types. Four possible structures of DBzSO were considered and the total energies were calculated for both a vacuum and in CDCl3 solvent. The change of length of S-O and S-C bonds in solvent was more obvious than that of the C(CH2)-C(C6H5) bonds; The S-O bond was longer and S-C bond was shorter in CDCl3. The essence effect of solvent on the properties of dibenzyl sulfoxide should come from the change of the geometrical structure. The change of shift Δx, [shift (solvent) - shift (vacuum)] showed that the effect of solvent on methylene protons of dibenzyl sulfoxide was apparent. Except of the other H of the rings, the two ortho H which were near S-O bond appeared more sensitivity on the solvent. The optimized structures in CDCl3 were in good agreement with the experimental data. The NMR peaks of methylene protons should be split more apparently in actual circumstance and the complex split of CH2 1HNMR peaks should be explained in some degree.

Oxidation of E,E‐bis(3‐bromo‐1‐chloro‐1‐propen‐2‐yl) chalcogenides and use of E,E‐bis(3‐bromo‐1‐chloro‐1‐propen‐2‐yl)sulfone in heterocyclization with primary amines

“…Magnetic nonequivalence of methylene protons of sulfoxides, such as dibenzyl sulfoxide, alkyl, benzyl and phenacyl sulfoxides, is well known. This feature is also reported for the adduct of propargylic alcohol with selenium dichloride .…”

“…This feature is also reported for the adduct of propargylic alcohol with selenium dichloride . But it is worthwhile to mention that in the case of dibenzyl sulfoxide, this nonequivalence manifests itself only in the solvents with high dielectric constants, while in the solvents with low dielectric permittivity, to which belongs CDCl 3 ( ε 4.67), methylene protons are magnetically equivalent . This fact has stimulated us to elucidate the difference of energy characteristics (in chloroform medium) of sulfoxide 2a , in which proton atoms of the methylene group are magnetically nonequivalent, and sulfone 3 and the starting sulfide 1a , in which these atoms are magnetically equivalent.…”