| 摘要 |
Pentoses are obtained by heating a primary aromatic amine N-pentoside, e.g. one derived from ribose, lyxose, xylose or arabinose, or a complex of such N-pentoxide with a greater or lesser proportion of an alkali metal or an ammonium salt such as sodium sulphate, sodium chloride, sodium citrate, sodium acetate, sodium dihydrogen phosphate or ammonium chloride, in solution in the presence of water until hydrolysis is substantially complete, separating the liberated primary aromatic amine, e.g. by reaction in situ with an aldehyde e.g. benzaldehyde, a substituted benzaldehydex or formaldehyde, or by steam distillation, if desired, under pressure or in vacuo, and isolating the pentose from the aqueous solution. Advantageously there may be added a small quantity of a volatile lower fatty acid, e.g. formic, acetic or propionic acid, or traces of strong acids, and a non-oxidising atmosphere is desirable. The hydrolysis is applicable equally to the two types of N-pentoside obtained by effecting condensation of the aromatic amine and the pentose, e.g. ribose, (a) by applying heat and (b) at room temperature. Suitable N-pentoxides are aniline-, alkoxyaniline-, chloaniline-, naphthylamine-, hydroxyaniline-, toluidine- and xylidine ribosides, specified compounds being aniline-, o-chloraniline, 3 : 4-dimethylaniline, o-hydroxyaniline, p-toluidine and a -naphthylamine-N-d-ribopyranosides and aniline, anisidine and 3:4-dimethylaniline-N-d-ribofuranosides. In examples: (1) a -aniline-d-ribopyranoside-sodium sulphate complex in water containing 0.25 per cent acetic acid is steam-distilled under nitrogen and the aqueous portion is treated with decolorizing carbon and evaporated to dryness in vacuo to isolate d-ribose; (2) a -aniline-d-ribopyranoside-sodium sulphate complex, containing 70 per cent of riboside, is suspended in absolute alcohol and treated with fresh benzaldehyde, prior to refluxing for 1/2 hour, diluting the filtrate with water, extracting with ether and evaporating the decolorized aqueous solution to isolate a -ribose; (3) the starting material of (2), suspended in water, is treated with fresh benzaldehyde and the mixture is refluxed under nitrogen for 1/2 hour, prior to isolating a -ribose as in (2); (4) a -aniline-d-ribopyranoside is treated (a) as in (1) or b) as in (2) to isolate d-ribose; (5) a -aniline-d-ribofuranoside is treated as in (1) to isolate d-ribose; (6) a -aniline-N-d-ribofuranoside is treated in hot aqueous solution with benzaldehyde and processed as in (2) to isolate d-ribose. Similarly, a -3 : 4-dimethylaniline-N-a -ribofuranoside is hydrolysed to yield d-ribose. Specification 599,013 is referred to. a -Aniline-N-d-ribofuranoside is obtained by heating under reflux for 1 hour a -aniline-N-d-ribopyranoside in absolute alcohol.
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