Nuclear Magnetic Resonance Investigation of Intramolecular Motions in Methylpyranosides

Proton spin‐lattice relaxation times T1 and T1 as well as the proton second moment have been measured for polycrystalline methyl α‐D‐glucoside, methyl β‐D‐glucoside and methyl β‐D‐galactoside over a wide temperature range. Analyses of the experimental data have yielded information about intramolecular reorientations in the solid state. C3 reorientations of methyl groups take place in all the samples. Potential energy calculations have shown that the CH2OH group can execute trans‐gauche jumps between two potential minima separated by 120. Analyses of the T1 and second moment data have confirmed the presence of this conformational motion. A weak relaxation mechanism, related to the dynamics of an OH group, has been revealed in methyl β‐D‐galactoside.