Chemical Constituents of the Animal Body. 205 



The oxidation by Fenton's reagent may be represented by 

 the equation - 



C 7 H 12 7 (gluconic acid) + - C 5 H 10 5 + C0 2 + H 2 0. 



V. Although all the reactions in the preceding four 

 sections show the stereometric relationships of certain 

 sugars one to another, they are insufficient to fix definitely 

 the correct formula for any given sugar. In order to 

 establish this, the positions of the hydrogen atoms and 

 hydroxyl groups in certain derivatives of the sugars must 

 be taken into account. It will facilitate the explanation 

 the reactions involved are first applied to the simpler 

 sugars. There are four possible isomerides of the sugars 

 containing four carbon atoms (that is, erythrose and its 

 somerides), namely 



CHO CHO CHO CHO 



3H- 

 OH- 



H 

 H 



H 

 H 



OH 

 -OH 



H 



OH 



OH OH 



H 



H 



CH 2 OH CH 2 OH CH 2 OH 



(1) (2) (3) 



'orming two pairs of enantiomorphs. 



Now these sugars can be reduced to alcohols 

 CH 2 OH 



(CH(OH)) 2 

 CH.OH 



-H 



-OH 



CH 



