Relative Signs of Spin-Spin Interactions in Nuclear Magnetic Resonance. II

Abstract

The spectrum of the allyl group in allyl amine is discussed in detail. The interpretation of the spectra of 1‐butene and 3,3‐dimethyl‐1‐butene are also discussed. It is shown how the chemical shifts, spin‐spin interactions, and in particular the relative signs of the latter can be determined by numerical methods. In all three molecules all spin‐spin interactions among the vinyl protons have the same sign. One of the three vinyl‐methylene interactions is found to have a different sign than the other two. This interaction has the same sign (and approximately the same magnitude) as the methyl‐methylene interaction in 1‐butene.