Xanthyl derivatives

Some amides do not dissolve in glacial acetic acid in such cases a mixture of 2 ml of glacial acetic acid and 3 ml of water may be used as a solvent for the reaction. Urea may be characterised as the di-xanthyl derivative (m.p. 274 °C) prepared in acetic acid. Di- and tri-chloroacetamide, oxamide, and salicylamide do not give satisfactory results. 

Xanthydrol test. Dissolve the compound in 50% acetic add and add to the solution 1 ml of 5 % methanolic xanthydrol reagent. An immediate predpitate of the xanthyl derivative is given by urea, urea salts and mono-substituted ureas. After recrystallization from aqueous dioxan, the product can be retained as a derivative. 

Melting point S-Benzyl thiuronium salt Acid chloride Amide Xanthyl derivative of amide Methyl derivative of amide Anilide Acetyl derivative of amide... 

Finally, we should like to point out the possibility of preparing oxalates (64) and Hg salts (65). The use of these methods, among which the preparation of xanthyl derivatives and oxalates will be illustrated by practical examples, is limited. Xanthyl and phthaloyl derivatives can be prepared from derivatives containing a --CONH2 group oxalates of amides have been prepared only from low-molecular-weight amides. 

For the identification of urea the preparation of xanthyl derivative can be employed. 

Crystalline derivatives may be prepared with xanthhydrol (9-hydroxy-xanthen), but the reagent is comparatively, expensive. Xanthhydrol reacts with primary amide,s with the formation of crystalline xanthyl-amides or 9-acylamidoxanthens ... 

Radicals derived from A-(o -xanthyl)acetanilides or A-(o -xanthyl)acetylamino-pyridines possessing a substituent next to the nitrogen undergo a Smiles rearrangement proceeding through a four-membered ring (Scheme 113).166... 

In 1932 Levene and Harris128 showed that the hydrolysis of xanthylic acid gave rise to the formation of a D-ribose phosphate which was not identical with the known D-ribose 5-phosphate. Since xanthylic acid is the monophosphate derivative of a ribofuranoside of xanthine it followed that the new phosphate was either D-ribose 2-phosphate or the 3-isomer (L). Shortly thereafter the same authors129 succeeded in reducing the new D-ribose phosphate with hydrogen in the presence of platinum oxide to a ribitol phosphoric acid (LI) which was completely... 

Protection of S -hydroxyl groups of 2 -deoxyrlbonucleosides. The 9-phenyl-9-xanthyl (pixyl) derivatives of 2 -deoxyribonucleosides have better crystallization properties than the corresponding, usually used, dimethoxytrityl ethers, but also have similar acid lability, being removable in 8-15 minutes by 80% HOAc at 20°. 

It is now known that mild, alkaline hydrolysis of ribonucleic acids yields mixtures of the 2 - and 3 -phosphates of ribonucleosides, although it had earlier been believed that only the 3 -phosphate derivatives are produced. For example, it was reported that guanylic acid (6), obtained from ribonucleic acid hydrolysates, is deaminated with nitrous acid to xanthylic acid (7), which was hydrolyzed at pH 1.9 to a ribose phosphate... 

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