Acetamido group, proton magnetic resonance

Free 4-acetamido-4,5-dideoxy-D (or L)-xylose is a syrup, and its infrared spectrum shows negligibly small bands for the imino and carbonyl groups. The syrup consists of two components, present in about equal amounts, - that are chromatographically separable. They yield the same (2-benzyl-2-phenyl)hydrazone, and are interconvertible by acid catalysis. Their optical rotations and their nuclear magnetic resonance spectra show that they are anomeric forms - of 195. Their nuclear magnetic resonance spectra are differentiated by the positions of the signals for their H-1 protons (t 4.72 and 4.84). The spectrum of each anomer shows, on acidification, a rapid attainment of anomeric equilibrium. A... 

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