BIOLOGICAL CHEMISTRY 



acetate in acetic acid solution whilst the disaccharides will 

 not.* 



Phenyl Hydmzine Test. The aldehyde or ketone oxygen 

 atom can be replaced by a molecule of phenyl hydrazine 

 forming a hydrazone. On heating with an excess of phenyl 

 hydrazine the neighbouring alcohol group is oxidised either 

 to an aldehyde or to a ketone group depending on whether 

 the neighbouring group was a primary or secondary alcohol. 

 A 



FIG. 2. Crystals of Phenylosazones. 



A. Crystals of phenyl glucosazone. 



B. Crystals of phenyl maltosazone. 



C. Crystals of phenyl lactosazone. 



D. Crystals of phenyl galactosazone. 



(Redrawn from photomicrographs.) 



A second molecule of phenyl hydrazine can now be added 

 and the resulting product is called an osazone. The osazones 

 are therefore compounds formed by two molecules of phenyl 

 hydrazine united to one molecule of sugar. 



* C. Barfoed, Fresenius' Zeit. f. anal. Chem., 1873, vol. 12, p. 27 ; H. E. 

 Roaf, Journal of Physiology, 1921, vol. 54, proc. p. Ix. 



