High-resolution nuclear-magnetic-resonance spectra of hydrocarbon groupings I. Some dichloro-propenes

An analysis has been made of the high-resolution nuclear-magnetic-resonance spectrum given by the hydrogen nuclei of 2:3-dichloropropene-l and cisand trans 1:3-dichloropropene-1. The spectra at 40 Mc/s of the 1:3-dichloropropenes were analyzed by means of the theory for ABX2 developed here; the 16·2 Mc/s spectra were analyzed according to the ABC2 theory by means of a digital computer. It is concluded that the ‘long-range’ spin-spin coupling constants between hydrogen nuclei on carbon atoms 1 and 3 of the 1 : 3-dichloropropenes are of opposite sign to the remainder. A correlation of these results with earlier work on butene-1 by Alexander (1958) leads to analogous conclusions for this molecule also.