Nuclear magnetic resonance spectra of the meso and dl-2,5-dichlorohexanes

Abstract

The high-resolution NMR spectra of the title compounds were treated as Y 3XAA′BB′X′Y 3′ systems. The analysis yielded the coupling constants and chemical shifts for the central methylene portions (AA′BB′). The relative magnitudes of the trans and gauche coupling constants show that the trans conformations about the central carbon-carbon bonds are favored. J AA′= J BB′ in the meso compound, but J AA′ ≠ J BB′ in the dl compound, reflecting the lack of symmetry in the latter structure. Long-range methine-methylene couplings were found to be small and negative.