Spin system
This tool is used to simulate second-order J coupling effects that can modify 1D NMR spectra. It allows you to predict and justify observed peak multiplicities.
It is not possible to compare the spin multiplicity prediction with experimental spectra.
Start by selecting your spin system depending on the number of spins involved (ABC — three spins, ABDC — four spins...) and specify their chemical shift (i.e., where they appear on your 1H spectrum). Add the value of the coupling constant between the spins of interest: Ji(Hz) corresponds to the coupling with spin i. Finally, specify the acquisition parameters that could affect peak definition (i.e., magnetic field strength, line width, and the number of data points).
To compare several predictions, use the Keep button. It enables you to freeze the first prediction, whose spectrum becomes green. Coupling constants or chemical shifts can then be modified and the new spectra will overlap in blue.
