Experimental and theoretical study of the ethoxy group conformational effect on 13c chemical shifts in ortho-substituted phenetols

The ¹³C chemical shifts of nine 2-X-substituted phenetol derivatives were measured together with the ¹³C chemical shifts of the corresponding X-monosubstituted benzenes. Using an additivity scheme, the ethoxy cis-and trans-ortho-SCSs (substituent chemical shifts) at C-6 and C-2, respectively, were determined to be shielding effects of 16.5 and 10.9 ppm, respectively, which are close to those determined previously in anisole derivatives. Optimized geometries at the Hartree-Fock level employing a D95** basis set for three different phenetol conformers were obtained and the corresponding chemical shifts of all ¹³C nuclei were calculated using the same basis set and the CHF-GIAO approach. Results are discussed in terms of different interactions defining different conformations, particularly that between a polar bond and a proximate highly polarizable one.

Duke Scholars

Author Julio Cesar Facelli Biostatistics & Bioinformatics, Division of Translational Bi ...