( l-i3 ) 



ït is my intention to also determine this equilibrium in the case 

 of other aliphatic and aromatic ketones and also aldehydes. 



The investigation of Urkch's diacetocyanohydrin and the products 

 of the action of gaseous hydrochloric acid on oxynitriles quoted by 

 Pinner ^) but as far as I know not further studied, has already been 

 taken in hand. 



In the light of the above results I have examined the different 

 modes of preparation of the ox^^nitriles more closely. 



Method 1. Dry hydrocyanic acid mixed with dry acetone and 

 kept for six months in a Avell-closed steamed flask is still completely 

 unchanged. On mixing, a slight rise in temperature took place. 

 That, however, no trace of the addition product has been formed 

 may be proved by first determining the total percentage of hydrocyanic 

 acid by means of the well-known titration with silver nitrate and 

 then by ascertaining the amount of free hydrocyanic acid in the 

 same way as was done in the determination of the equilibria. We 

 will then find the same figures. After six months the mixture still 

 showed the same refraction, which also proves that no change had 

 yet taken place. 



The reason why previous investigators obtained cyanohydrin all 

 the same may be safely attributed to the fact that there were still 

 present traces of moisture and that minute traces of alkalis from the 

 glass vessel considerably accelerate the reaction. 



It is now also obvious why the methods 2 and 3 should lead to 

 a good result as the alkaline potassium cyanide is always present in 

 excess. It need hardly be said that the formation of nascent hydrogen 

 cyanide previously looked upon as the most important factor in 

 method 2 has nothing to do with the real reaction. 



Although former investigators ^) have not succeeded in preparing pure 

 cyanohydrin by the second method, nothing is easier than the isolation 

 of the pure nitrile by distillation under reduced pressure, if only care 

 be taken to have a slight excess of hydrocidoric acid present after 

 the reaction has taken place. 



The following are the chief properties of the nitriles, as yet 

 investigated. 



Dimetlii/lketonecyanohydrin is a perfectly colourless liquid practically 

 odourless. Sp. gr. at 18° 0,9342. Decomposes on distillation at the 



1) B. B. 17, 2009. 



2) Urech, Ann. 164, 255. 



TiEMANN u. Friedlander, B. B. 14, 1970. 



