340 



Tlirougli tlie formation of a second oxide ring, we then arrive at 

 the following formula for the second anhydride 



OH 



r— , I 



CH,-CH— CH— CH— CH— CH, . 



I I I 



OH 



The places of the OH-groups here are at 2.5; hence no acetone 

 derivative can be formed, nor will the conductivity of boric acid 

 be raised. On treatment with acetone and 1 "/, hydrochloric acid 

 the isomannide was actually recovered. The results of the measure- 

 ments of the conductivity are recorded in the following table: 



The concentrations were 0,2 mol. /Litre. 



After deduction of the conductivity for water 3 X 10"^, we 

 find therefore that iso-mannide in a very small, quite negligible 

 degree increases the conductivity, whereas this increase for man- 

 nitane exceeds that of mannitol more than 27, times. 



Of the forgoing we may conclude that the structure of the un- 

 saturated oxide C\HgO is proved, likewise that of mannitane. The 

 given formula for isomannide seems to be exceedingly probable. 



Utrecht, Org. Chem. Labor, of the University. 



