Problems

 

After a series of Kiliani-Fischer syntheses on (+)-glyceraldehyde, an unknown sugar is isolated from the reaction mixture. The following experimental information is obtained:

(a) Molecular formula, C₆H₁₂O₆.

(b) Undergoes mutarotation.

(c) Reacts with bromine water to give an aldonic acid.

(d) Reacts with phenylhydrazine to give an osazone, mp 178°C.

(e) Reacts with HNO₃ to give an optically active aldaric acid.

(f) Ruff degradation followed by HNO₃ oxidation gives an optically inactive aldaric acid.

(g) Two Ruff degradations followed by HNO₃ oxidation gives meso -tartaric acid.

(h) Formation of the methyl glycoside (using CH₃OH and HCI), followed by periodic acid oxidation, gives a mixture of products that includes (+)-glyceraldehyde.

(i) Draw a Fischer projection for the open-chain form of this unknown sugar.

 

Text Books

 

• •  P. Y. Bruce and K J R. Prasad, Essential Organic Chemistry , Pearson Education, New Delhi, 2008.

  •  R. R. Morrison, R. N. Boyd and S. K. Bhattacharjee, Organic Chemistry , Dorling Kindersley (India) Pvt. Ltd, 2011, New Delhi, 2011.