THE CARBOHYDRATES 199 



Reactions. 



Cane sugar differs considerably from glucose in many of its 

 reactions. 



(1) Formation of Esters. Cane sugar forms esters with eight 

 hydroxyl groups. 



(2) Formation of Compounds with Metallic Hydroxides. Cane sugar 

 forms insoluble compounds with lime, strontia, lead hydroxide, etc., 

 more easily than glucose; this property as mentioned above is made 

 use of in its commercial preparation. 



(5) Action of Alkali. Cane sugar, since it contains no aldehyde or 

 ketone group, is not acted upon by alkali and does not give Moore's 

 test. 



(6) Action of Hydrochloric Acid. Cane sugar is easily hydrolysed 

 by boiling with dilute hydrochloric acid into glucose and fructose. 

 Concentrated hydrochloric acid has the same action upon it as upon 

 fructose (and glucose). 



(7) Reduction of Metallic Oxides in Alkaline Solution, Cane sugar 

 does not reduce Fehling's solution, etc. Cane sugar, after hydrolysis 

 by boiling with dilute acid and neutralisation of the acid with sodium 

 hydroxide, reduces Fehling's solution, etc. 



(9) Formation of Osazones. Cane sugar does not form a phenyl- 

 osazone. After hydrolysis by acids into glucose and fructose, phenyl- 

 glucosazone is formed. 



(10) Fermentation. Cane sugar is fermented by yeast, but before 

 fermentation into carbon dioxide and alcohol it is converted by 

 hydrolysis by the enzyme, invertase, in the yeast into glucose and 

 fructose. 



(11) Molischs Test. Cane sugar gives Molisch's reaction. 



(12) Rotati9n. Cane sugar is dextrorotatory. After hydrolysis by 

 acids the mixture of glucose and fructose in equal parts shows laevo- 

 rotation due to the laevo-rotation of fructose being greater than the 

 dextro-rotation of glucose. Owing to the change of rotation, or in- 

 version, the mixture of glucose and fructose obtained from cane sugar 

 is generally spoken of as invert sugar. 



Cane sugar gives SelivanofT's reaction since it contains fructose. 



