DERIVATIVES OF SUGARS. 197 



also occurs in the animal body. NEUBERG and MAYER l have shown by 

 experiments on rabbits the direct partial transformation of various 

 mannoses into the corresponding glucoses. Another example is, it 

 seems, the formation of galactose (see milk sugar) from glucose in the 

 mammary gland. 



By the action of strong alkali the sugars are decomposed with the 

 formation of lactic acid and many other products. 



With ammonia the glucoses may form compounds which have been 

 considered as osamines by LOBRY DE BRUYN, but to differentiate them 

 from the true osamines have been called osimines by E. FiscHER. 2 The 

 corresponding osaminic acid can be obtained from such an osimine by 

 the action of ammonia and hydrocyanic acid, and from the hydrochloric- 

 acid lactone of this acid the osamine is obtained by reduction with sodium 

 amalgam. In this manner E. FISCHER and LEUCHS artificially prepared 

 first d-arabinosimine from c?-arabinose, then d-glucosaminic acid and 

 finally from its lactone d-glucosamine, which occurs in the animal body. 

 In a similar manner they 3 obtained Z-glucosamine from /-arabinose. 



KNOOP and WINDAUS 4 have obtained large amounts of methylimida- 



CH 3 



zol, C NH\ , from glucose by the action of ammonium-zinc hydroxide 



CH Nr 



at ordinary temperatures. This formation can be conceived as follows: 

 First methyl glyoxal is formed from the sugar, and then from this or 

 from the sugar formaldehyde is produced, which reacts with the methyl 

 glyoxal with the formation of methylimidazole according to the following 

 equation : 



CH 3 CO NH 3 H x H.C.C NH 



| + + >CH= || 

 COH NH 3 0' CH N 



Methylglyoxal Formaldehyde Methylimidazole 



A genetic relationship of the carbohydrates to histidine and the purine 

 bodies is thus made probable by the imidazole formation. 



As the sugars are derivatives of polyhydric alcohols, they also form 

 esters, among which the benzoyl ester is of special interest because it is 

 used in the detection and isolation of the sugars and also of other car- 

 bohydrates. The nucleic acids probably also belong to the acid esters 

 of the sugars, and thus may be considered as complex phosphoric acid 



1 Zeitschr. f. physiol. Chem., 37. 



2 Lobry de Bruyn, Ber. d. d. chem. Gesellsch., 28; E. Fischer, ibid., 35. 



3 Ibid., 36 and 35, p. 3787. 



4 Ibid., 38, and Hofmeister's Beitrage, 6. 



