High-resolution deuterium NMR spectra of styrene-α-d, styrene-dg, 1-vinylnaphthalene-α-d, and 2-vinylnaphthalene-α-d in hydrocarbon solvents were recorded at field strengths of 14.11 to 14.57 T. Quadrupolar splittings were observed as a consequence of magnetic field-induced alignment of the solute molecules. The magnitudes of the splittings were used to calculate the average value of sin2 α, where α is the dihedral angle between the vinyl and ring planes; αrms = sin-1 (sin2 α)1/2 was 16.5 ± 0.9° for styrene, 18.3 ± 3.1° for 2-vinylnaphthalene, and 41.8 ± 4.1° for 1-vinylnaphthalene. The styrene value was used to deduce the magnitude of the twofold rotational barrier and the extent of steric destabilization of the planar form. The results are compared with available literature data.
ASJC Scopus subject areas
- Colloid and Surface Chemistry