IR spectra and hydrogen bonding in tetritols

The out-of-plane (τ) H-vibration bands in spectra of polycrystalline films of two isomeric alditols, meso-erythritol and d,l-threitol, were recorded at 300 K and at 20 K for both OH and OD compounds and the H-band parameters were used for the evaluation of the relative strengths of the H-bonds in the crystals of two tetritols. Unlike erythritol, in the crystals of which all the H-bonds are strong, threitol contains additional weak H-bonds. This fact might be related to the strong water absorption capability of d,l-threitol, as compared to the reluctance of meso-erythritol to absorb water. The enhanced water absorption capability of d,l-threito1 as compared to meso-erythritol is ascribed to differences in strength of H-bonds in the crystals based on IR spectral data.