66 THE CARBOHYDRATES. 



(3) CH 2 (OH).CH(OH).CH.(OH).CH(OH).C.CH.N.NH.C 6 H 6 +2H 2 0+2HC1 = 



N.NH.C 6 H 6 . 

 2NH 3 .NH.C 6 H 6 .HC1 -f CH 2 (OH).CH(OH).CH(OH).CH(OH).CO.COH. 



Oson. 



(4) CH 3 (OH).CH(OH).CH(OH).CH.(OH).CO.CHO + 2H= 



CH 2 (OH).[CH(OH)] 3 .COCH 2 (OH) 



Lsevulose. 



The same result may be reached when the corresponding osazon 

 of the aldose is directly reduced, and the resulting osamin is treated 

 with nitrous acid : 



(1) CH 2 (OH).CH(OH).CH(OH).CH(OH).C.CH.N.NH.C 6 H 6 + H 2 O + 4H = 



Phenylglucosazon. 



N.NH.C.H, 

 CH 2 (OH).CH(OH).CH(OH).CH(OH).CH(NH. 2 ).COH + 



Glucosamin. C 6 H 5 .NH 2 .NH -f C 6 H 5 .NH 2 



Phenylhydrazin ani'lin. 



(2) CH 2 (OH).CH(OH).CH.(OH.)CH(OH).CH(NH,).COH f HNO 2 =: 



Glucosamin 



H 2 + 2N + CH 2 (OH).CH(OH).CH(OH).CH(OH).CO.CH 2 (OH) 

 Laevulose. 



The glucosamiu thus obtained as an intermediary product is of 

 special interest in so far as it also results from the decomposition of 

 the hyalins chitin and chondroitin. By oxidation with bromine gluco- 

 samin then yields chitonic acid, from which the corresponding sugar, 

 chitose, can be obtained on reduction : 



(1) C ]8 H 30 N 2 12 + 4H. 2 O = 2CH 2 (OH).CH(OH).CH(OH).CH(OH). 



Chitin - Glucosamin. CH(NH 2 ).COH + 3CH V COOH 



(2) CH. 2 (OH).CH(OH).CH(OH.)CH(OH).CH(NH 2 ).COH + 4O = 



CH 2 (OH).CH(OH).CH(OH).CH.(OH).CH(OH).COOH + HNO, 



Chitonic acid 



(3) CH 2 (OH).CH(OH).CH(OH).CH(OH).CH(OH).COOH -f 2H = 



CH 2 (OH).[CH(OH)] 4 .COH + H 2 O 

 Chitose 



On boiling with dilute mineral acids the hexoses are decomposed 

 into formic acid, Isevulinic acid, and certain humin substances. With 

 the alkalies, on the other hand, they yield, besides other products, 

 also laevulinic acid and a ke tonic acid of the composition CH 3 .CO. 

 CH 2 .CH 2 .COOH. This formation of Isevulinic acid, especially on 

 boiling with concentrated hydrochloric acid, may be regarded as 

 one of the characteristics of carbohydrates which are composed of 

 6 atoms of carbon. On the application of dry heat they form 

 so-called caramel, and are finally carbonized. During the process 

 of dry distillation, as also on distillation with hydrochloric acid, a 

 slight formation of furfurol occurs. 



On treating a small amount of a hexose solution (0.5 c.c.) with a 

 drop of a 10 per cent, solution of a-naphthol in alcohol (free from 

 acetone) and underlaying with concentrated sulphuric acid (1 c.c.) a 

 reddish-violet color develops at the zone of contact. The reaction, 

 which is known as Molisch's reaction, depends upon the formation of 

 furfurol from the sugar under the action of sulphuric acid. 



