Long-Range Coupling in the NMR Spectra of Aldehydic Protons in Aromatic Compounds

Abstract
The proton signal of the O=C–H group in ortho‐substituted benzaldehydes shows a coupling with a ring proton. The analysis of the spectra of 2,4‐dichlorobenzaldehyde, 2,4‐dimethoxybenzaldehyde, and 2,4‐dihydroxybenzaldehyde shows that the observed splitting is due to a coupling with a ring proton situated five bonds away.