AND POLYHYDRIC ALCOHOLS 173 



and unhydrolysed material. Similarly, when the reaction 

 was arrested at a time corresponding to the second maximum 

 on the curve, the product was essentially mannitol monoacetone. 



The formation of a definite mannitol diacetone, as the 

 first step in the production of the monoacetone derivative, is 

 obviously of great importance in tracing the course of this 

 interesting hydrolysis, as it eliminates the possibility of the 

 hydrolytic change being confined, in the first instance, to the 

 acetone residues coupled in the primary alcoholic positions. 

 Moreover, it indicates that there is a difference in the stability 

 with which the terminal residues A t and A 3 are attached to 

 the molecule, although the general symmetry of the structure 

 would not justify this conclusion except on the assumption 

 that there is a difference in the linkage of the groups (A 1 and 

 A s ). The study of mannitol monoacetone lends support to 

 this view. Methylation of the compound by the silver oxide 

 reaction resulted in the formation of tetramethyl mannitol 

 monoacetone, from which tetramethyl mannitol was obtained 

 on hydrolysis. The fact that this compound may be oxidised 

 by Fenton's reagent to give an alkylated reducing aldose, 

 shows that the stable acetone residue was originally attached 

 to a terminal primary alcohol group. 



This series of reactions may therefore be interpreted in 

 the following way : 



CH 2 N 



3(Me) 2 Trans. 



CHO 



I 

 CHC 



CHO 



- 



)>C(Me)o Trans. 

 ' 



C 



HO\ 



>C(Me) 2 Cis. 

 X 



