The chemical shifts and the conformations of linear hydrocarbons

Abstract The proton chemical shifts of some hydrocarbons ( n ‐C 9 H 20 , n ‐C 10 H 22 , n ‐C 11 H 24 , and n ‐C 22 H 46 ) were calculated assuming the extended chain with one gauche form and predominant contribution of the magnetic anisotropy effect of the C‐C bonds along the chain. It is suggested that the high field peak of the two splitted methylene signals of n ‐C 22 H 46 in α‐chloronaphthalene (α‐CINap) solution is assigned to the methylene protons next to the gauche bond in a planar zigzag chain, of which molecular motion is restrained strongly by α‐CINap molecules and the second methylene group next to the terminal methyl group, whereas the low field peak is assigned to other methylene protons, the molecular motion of which is restrained weakly. A small peak at lower field than the two large peaks is assigned to the gauche methylene protons in a planar zigzag chain the molecular motion of which is restrained by α‐CINap molecules.