64 



CARBOHYDRA TESMONOSACCHARIDES 



verted by reduction into Alcohols, so, by oxidation, they are converted 

 into acids. Glucose yields three different 6-carbon atom acids on 

 oxidation. Two of these acids are monobasic and the third is dibasic. 



CH 2 OH 



Glucose. 



COOH 

 I 

 H C OH 



HO C H 

 H C OH 

 H C OH 



CH 2 OH 



Gluconic acid. 



CHO 



H C OH 

 HO C H 

 H C OH 



H C OH 



I 



COOH 

 Glucuronic acid. 



COOH 

 I 

 H C OH 



HO C H 



I 

 H C OH 



I 

 H C OH 



I 



COOH 

 Saccharic acid. 



From mannose the dibasic acid which is obtained is Manno-sac- 

 charic Acid. From galactose the dibasic acid which results from 

 oxidation is Mucic Acid. The ketoses, including levulose, behave quite 

 differently on oxidation. The aldoses, on being oxidized yield acids 

 containing the same number of carbon atoms as the original sugar. 

 The ketoses, on the contrary, break down on oxidation and yield 

 compounds containing fewer carbon atoms than the original sugar. 



Similar relationships subsist among the sugars which contain fewer 

 than six carbon atoms. Thus we have: 



BIOSES. 



Alcohol. 

 CH 2 OH 



I 

 CH 2 OH 



Glycol. 



Sugar. 

 CHO 



CH 2 OH 



Glycolose. 



Monobasic acid. 

 COOH 

 I 



CH 2 OH 

 Gly collie acid. 



Dibasic acid. 

 COOH 



COOH 



Oxalic acid. 



TRIOSES. 



Alcohol. 

 CH 2 OH 



CHOH 



CH 2 OH 

 Glycerol. 



CH 2 OH 

 I 

 CHOH 



CHOH 



CH 2 OH 



Erythritol. 



Sugar. 

 CHO 



CHOH 



CH 2 OH 



Glycerose. 



Monobasic acid. 

 COOH 



CHOH 



CH 2 OH 



Glyceric acid. 



TETROSES. 

 CHO COOH 



CHOH 



I 

 CHOH 



I 



CH 2 OH 

 Erythrose. 



CHOH 

 CHOH 



CH 2 OH 



Erythric acid. 



Dibasic acid. 

 COOH 



CHOH 



I 

 COOH 



Tartronic acid. 



COOH 

 I 

 CHOH 



CHOH 



COOH 



Tartaric acid. 



Similarly, the pentose Arabinose corresponds to the alcohol 

 Arabitol and to the acids Araboric and Trioxyglutaric, while the pentose 

 Xylose corresponds to the alcohol Xylitol. 



