CARBOHYDRATES AND THEIR 



[CH. 



the hydrolysis of cane-sugar and maltose, and, in all probability, is the 



first sugar synthesized from carbon dioxide and water. Its synthesis and 



its relationships to other sugars will be discussed later (see p. 69). It is 



a white crystalline substance, readily soluble in water and aqueous 



alcohol, but only slightly soluble in absolute alcohol. 



If, as in the case of a pentose, we examine the structural formula for 



a hexose, such as glucose : 



H— C = 



H— C*— OH 



HO— C*— H 



H— 0*— OH 



H— 0*— OH 



I 

 H— 0— H 



I 

 OH 



we see that there are four carbon atoms marked * which are united 

 to four different groups of atoms. It will be found in this case that there 

 are sixteen possible isomers : 



OHO 



I 

 H_C~OH 



I 

 H— 0— OH 



i 

 HO— C— H 



I 

 HO— C— H 



I 

 CH.OH 



Z-Mannose 



OHO 



I 

 HO— C— H 



I 

 HO 0— H 



I 

 H— C— OH 



I 

 H— C— OH 



I 

 CH.OH 



(j?-Mannose 



OHO 



HO— C— H 



I 

 H— C— OH 



I 

 HO— 0- H 



I 

 HO— C— H 



I 

 CH.OH 



Z-Glucose 



OHO 



! 



H— 0— OH 



I 

 HO— C— H 



H— C— OH 



I 

 H— 0— OH 



I 

 OH,, OH 



</-C41ucose 



CHO 



I 

 HO— C— H 



I 

 H— C— OH 



I 

 HO— C— H 



H— C— OH 



1 

 CHoOH 



Z-Idose 



CHO 



I 

 H— C— OH 



I 

 HO— C— H 



H— C— OH 



I 

 HO— C— H 



I 

 CH.OH 



o?-Idose 



CHO 



1 

 H— C— OH 



I 

 H— C— OH 



I 

 HO- C— H 



I 

 H— C— OH 



i 

 CH.OH 



Z-(Julosc 



CHO 



I 

 HO— C -H 



I 

 HO— C— H 



I 

 H— C— OH 

 1 

 HO— C— H 



I 

 CHoOH 



f/-Gulos!e 



