196 Biological Chemistry. 



conditions of experiment dextrose will yield an amount of 

 cuprous oxide different from that yielded by the same 

 amount of laevulose, and this " reducing power " of sugars 

 must be determined separately with each individual 

 member of the class.* 



The sugars also react, like other aldehydes and ketones, 

 with hydroxylamine to form oximes, the oxime of dextrose 

 having the formula 



CH 2 (OH).CH(OH)-CH(OH)CH(OH)CH(OH)CH:NOH 



The Action of Phenylhydrazine on Dextrose and 

 Lcewlose. The action of phenylhydrazine on these sugars 

 is an important one. The first action, both on dex- 

 trose and laevulose, is the one which would be expected 

 from the fact that these substances are an aldehyde 

 and ketone respectively. They form products known as 

 hydrazones.-)- 



CH.(OH)-(CH(OH)) 4 CHO + NH 2 -NH C 6 H 5 



= H 2 +CH 2 (OH)(CH- OH) 4 CH : N-NHC 6 H 6 

 CH 2 (OH)(CH(OH)) 3 CO CH 2 OH + NH 2 NHC 6 H 5 



= H 2 + CH 2 (OH)(CH(OH)) 3 C: N-NHC 6 H 5 



4 



Now when these hydrazones are heated with excess of 

 phenylhydrazine, a group CH(OH) in the case of dextrose, 

 and a CH 2 OH group in the case of laevulose, loses 

 hydrogen, which reacts with phenylhydrazine in accordance 

 with the following equation 



C 6 H 5 NH.NH 2 + H, = C 6 H 6 NH 2 + NH 3 



Products are thereby produced from dextrose and laevulose 

 having the two following formulae : 



. * For full details of the methods reference must be made to text-books on 

 quantitative analysis. 



f These formulse are written in an abbreviated form. 



