How do you calculate the coupling constant of doublet of doublet in proton NMR?

In proton NMR, the coupling constant (J) for a doublet of doublets can be determined by measuring the distance between the peaks of the doublet patterns in the spectrum. Each doublet arises from spin-spin coupling with neighboring protons, and the coupling constant is expressed in Hertz (Hz). To calculate J, measure the distance between the center frequencies of the peaks (in Hz) for each doublet and average the values if necessary. Additionally, ensure that the coupling constants are consistent within the same multiplet for accurate interpretation.