Vicinal proton-proton coupling constants

This program calculates 3JHH values according to Haasnoot et al.. Since the equation depends on the relative orientation of the substituents a molecular model will be of help. Turn the model so that the proton on the near side is pointing up then use the schemes below to determine the numbering of the substituents (e.g. S1, S2 etc.) and select the appropriate elements from the menus.
The program will automatically select to correct equation (C, D, or E) depending on the number of attached hydrogens.

"The relationship between proton-proton nmr coupling constants and substituent electronegativities-I"
C.A.G. Haasnoot, F.A.A.M. DeLeeuw and C. Altona
Tetrahedron 1980 36, 2783-2792

(Adopted from Dr. Roland Stenutz homepage)

S1 S2 S3 S4
H/H torsion angle => 3JHH