HEXOSES 103 



-O- 



CH2— (CHOH)3— C— OH— CHoOH 

 I 



Normal crystalline fructose 



CHjOH— CH— (CHOH).,— C— OH . CH.pH 



II 



y-fructose 



Haworth and his fellow-workers * from their considerable 

 experimental work conclude that the normal form of hexoses, 

 both aldehydic and ketonic and of pentoses, is the amylene 

 oxide form, and accordingly the ordinary form of fructose is 

 represented by the formula I. It has, however, been shown 

 by Irvine and Steele f that fructose, as it occurs in sucrose 

 and inulin, is present in a so-called y-form which is more 

 active than in its normal state. The y-form, which has the 

 butylene oxide configuration shown in formula II., differs from 

 ordinary, or normal, fructose in the fact that it reduces potas- 

 sium permanganate readily ; it may be produced by leaving 

 ordinary fructose in contact with acid for an hour and then 

 neutralizing ; the solution has thus acquired the power of 

 decolorizing permanganate. 



SORBOSE. 



Sorbose is a 2 keto-hexose, isomeric with fructose, of the 

 formula— 



OH H OH 



i- 



I I I 



H OH H 



It does not occur naturally, but is produced by the oxidative 

 action of Bacterium xylinum upon the alcohol sorbitol ; it 

 was, in fact, first isolated from the juice of Pyrus aucuparia 

 which had been kept for some months exposed to the air. 

 It has since been shown that the fresh juice contains no 

 sorbose but only the corresponding alcohol sorbitol. Bertrand :j: 



* Haworth and Hirst : " J. Chem. Soc," 1926, 1858. Avery, Haworth, 

 and Hirst: id., 1927, 2308. Goodyear and Haworth : id., 1927, 3140. 

 t Irvine and Steele : id., 1920, 117, 1474. 

 X Bertrand : " Ann. Chim. Phys.," 1904 [8], 3, 200. 



CH,OH . C— C ^C— CO . CH2OH 



