Thomas R. Hoye and Hongyu Zhao, "A Method for Easily Determining Coupling Constant Values: An Addendum to "A Practical Guide to First-Order Multiplet Analysis in ^{1}H NMR Spectroscopy," J. Org. Chem., 2002, 67, 4014-4016. Web copy
Antony Williams, Sergey Golotvin, Eugene Vodopianov, "J-Coupler - A Tool for Automated First Order Multiplet Analysis," March 11- 16, 2001. Orlando, Florida, USA, 42nd ENC, J-coupler [pdf]
The Altona equations are more accurate. Please see: C. A. G. Haasnoot, F. A. A. M. DeLeeuw and C. Altona, "The Relationship Between Proton-Proton Coupling Constants and Substituent Electronegativities-I," Tetrahedron, 1981, 36(19), 2783-2792.
The ^{3}J vinyl and ^{4}J allylic coupling constants
are estimated by the modified
Karplus Equation:
^{3}J = 6.6 cos^{2}(phi) + 2.6 sin^{2}(phi) | (0^{o}<= phi <= 90^{o}) |
^{3}J = 11.6 cos^{2}(phi) + 2.6 sin^{2}(phi) | (90^{o}<= phi <= 180^{o}) |
^{4}J = 1.3 cos^{2}(phi) - 2.6 sin^{2}(phi) | (0^{o}<= phi <= 90^{o}) |
^{4}J = - 2.6 sin^{2}(phi) | (90^{o}<= phi <= 180^{o}) |
For the other coupling types, typical values are listed in Table 3.26i, 3.27, and 3.29 in D. H. Williams, I. Fleming, "Spectroscopic Methods in Organic Chemistry,4th ed.," McGraw-Hill, London, 1987. pp 143-146. For more exact calculations, including second order effects please see JD: Spin-Spin Splitting Simulation
Colby College Chemistry