ACD/Labs Blog

In a substituted benzene ring, aromatic protons that are in the meta position can exhibit coupling to each other. This is referred to as meta or 4J coupling. The coupling pattern is typically a doublet with a coupling constant of ~2 Hz. On the contrary, a spectrum without any meta coupling indicates a lack of protons...

The second-order effects (also known as tilting or roofing) exhibited by multiplets can be used to identify multiplets coupled to each other. The 1H NMR spectrum below illustrates an example of strong coupling among three multiplets. The peak intensities across Multiplets A and B are different, that is, the peak on the right side of...

A window function (also known as apodization function or convolution) is applied to an FID to emphasize a region of the FID over another. The general goal is to improve the SNR (Signal-to-noise) ratio. The early stages of processing such as applying the “correct” window function can affect the time spent on an elucidation especially...

1H-1H couplings arise from influences on a proton’s magnetic field induced by the magnetic field of a neighbouring proton(s). As a proton experiences coupling from a neighbouring proton, so too is the coupling reciprocated to the neighbouring proton(s). By measuring the J-coupling for each splitting pattern, the proton connectivity information can be deduced. By comparing...

Proton-proton couplings arise from influences on the proton’s magnetic field from the magnetic field of neighbouring protons. Being capable to recognize among the vast array of coupling patterns can facilitate the time spent on interpreting a 1H NMR. The diagram below illustrates two coupling patterns: a triplet of doublets (td) and a doublet of triplets...