Electronegative and electropositive substituents

As the electronegativity increases the peak is shifted downfield (to a higher ppm)

As the substitution increases the peak is shifted downfield (to a higher ppm)

Electronegative substituents shift peaks downfield at a greater strength than increasing the substituents do.

Inductive Effects
Inductive effects run through the sigma-framework. There are also mesomeric effects working through the conjugation of the p- and pi-orbitals.

The protons which are closer to the direction of the negative charge are shifted to a higher ppm. The protons at the lower slightly positive charge won't be shifted as high.

	Created by abbeyjarvis about 11 years ago

Undergraduate CHM2WS1 Note on H NMR Spectroscopy, created by abbeyjarvis on 21/11/2013.