Infra-red Spectra of Deuterium-labelled Carbohydrates

Abstract

IN a previous report¹ we showed that the stretching frequency of the axial C₁—D in the 1-deutero derivatives of β-D-glucose and β-D-mannose was about 40 cm.⁻¹ lower than the corresponding equatorial C₁—D in the 1-deutero derivatives of α-D-glucose and α-D-mannose. Examination of a further series of 1-deutero carbohydrate derivatives (see Table 1) has revealed that this is a general feature of hexo-pyranose derivatives and that the stretching frequencies of the equatorial C₁—D groups of two crystalline D-pentopyranoses also fall in the same range as those of other equatorial groups. Although these stretching frequencies (some of which appear double) were measured with a sodium chloride prism and not therefore with great accuracy, the consistent differences were beyond experimental error and it was possible to resolve the frequencies of both anomers in the spectra of impure samples. The C—H stretching frequencies were not resolved by the infra-red spectrometer used in this work; the frequency of the approximate centre of the C—H stretching band was used in calculating the ratios recorded in Table 1.