Glucosylamine Schiff-base structure

However, he did find an absorption band at 6.05 n for solid A -o-tolyl-o-glucosylamine, and also for fV-2-naphthyl-D-glucosylamine, indicating for the first time the existence of a Schiff-base structure for A -substituted glucosylamines in the solid state. For the other A -substituted o-glucosyl-amines tested (A-phenyl, A-p-nitrophenyl, and A-m-nitro-p-tolyl), no Schiff-base structure was indicated. All compounds exhibited a band at 2.88 n which could have been given by either an NH or an OH grouping. 

The SchifF-base structure (XXVI) was proposed (Legay, 1952) for N-o-tolyl-o-glucosylamine, because it exhibited a C=N band at 1653 cm . However, the pure compound shows no band (Ellis, 1966) at 1653 cm , indicating that the structure is cyclic, probably the pyranoid form (XXVII). All the spectra of N-substituted glycosyl-amines examined by Ellis (1966) indicated the compounds to be cyclic. 

When the reaction was first applied to the sugars, amorphous products were obtained which were considered to have the Schiff base structure. By heating glucose or fructose in an alcoholic solution of aniline, Sorokin 10) was able to prepare crystalline products, although the crystallinity of iV-phenyl-D-glucosylamine is in doubt 10, 11). Many other crystalline glycosylamines are known at present in the aliphatic 5, 12) and aromatic 13,14) series of amines. 

Infrared spectroscopic data (28) for solid A-o-tolyl- and iV-jS-naphthyl-D-glucosylamine shows peaks at 6.05 /x- Such peaks are usually due to a —C=N— grouping, indicative of a Schiff base. The compounds p-tolyl-and p-nitrophenyl-D-glucosylamine, however, do not show such a peak. In the reaction between 2,3,4,5-tetra-0-acetyl-aZde%do-D-ribose and aniline in ethanol or methanol, crystalline compounds corresponding to the Schiff base type (V) were isolated these contained one molecule of ethanol or methanol. The infrared absorption spectra of these compounds, however, showed that they did not have the Schiff base structure (V), but were of... 

As we stated previously, glucose forms some, but not all, of the common carbonyl derivatives. The amount of free aldehyde present in solution is so small that it is not surprising that no hydrogen sulfite derivative forms. With amines, the product is not a Schiff s base but a glucosylamine of cyclic structure analogous to the hemiacetal structure of glucose, Equation 20-3. The Schiff s base is likely to be an intermediate that rapidly cyclizes to the glucosylamine ... 

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