Related Experiment Video
Updated: Aug 9, 2026

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
Stereoelectronic substituent effects
Henrik Helligsø Jensen1, Mikael Bols
1Department of Chemistry, University of Aarhus, DK-8000 Aarhus C, Denmark.
Abstract:
An investigation was carried out on the influence of the stereochemistry of substituents, particularly hydroxyl groups, on their electronic effects in piperidines, carbohydrates (pyranosides), and related compounds. Polar groups, such as OH, OR, and F, were found in the 3 and 4 position to be much more electron-withdrawing when positioned equatorially rather than axially. In contrast, little difference in electronic effects was observed from apolar groups as a result of epimerization. These observations were believed to be caused by differences in charge-dipole interactions and were used to explain why stereoisomeric glycosides hydrolyze with different rates. The conformational changes of hydroxylated piperidines and related compounds as a function of pH were likewise explained from the different substituent effects of axial and equatorial OH groups.
Related Concept Videos
Directing and Steric Effects in Disubstituted Benzene Derivatives
Directing Effect of Substituents: meta-Directing Groups
Inductive Effects on Chemical Shift: Overview
SN2 Reaction: Stereochemistry
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not observed.
Directing Effect of Substituents: ortho–para-Directing Groups
Radical Reactivity: Steric Effects
Along with electronic factors, steric factors also account...

