JACKSON AND GRINDLEY. — ACETALS FROM QUINONES. 419 



the hemiacetal dropping back to dichlordiethoxyquinone. Its proper- 

 ties were strangely unlike those of the correspoudiiig hemiacetal, for 

 whereas the dichlordiethoxyquinone hemiacetal was essentially in- 

 soluble in all solvents, the tetraethylacetal was so easily soluble in all 

 the common solvents except water, that it was hard to crystallize it 

 from any of them. The most striking property of the hemiacetal was 

 its instability, since it gave up ethyl alcohol at temperatures from 

 140° to 143°, becoming converted into the dichlordiethoxyquinone 

 (mekino- at 104°-10o°) ; the tetraethylacetal, on die other hand, melts- 

 without decomposition at 10r-102°, and from 205° to 275° sublimes 

 apparently unaltered. The hemiacetal is converted into dichlordie- 

 thoxyquinone when treated with acids, even more easily than by heat^ 

 dilute sulphuric or hydrochloric acid acting on it slowly even in the 

 cold, rapidly when warmed. This is its most marked property ; in 

 fact, it is so susceptible to the action of acids that in our earlier prep- 

 arations we obtained a considerable amount of dichlordiethoxyquinone 

 by drying the hemiacetal at ordinary temperatures, when it had not 

 been washed enough to remove the last traces of acid. In order to 

 bring about a similar decomposition of the tetraethylacetal it is neces- 

 sary to boil it with sulphuric acid of specific gravity 1.44. A more 

 dilute acid does not act upon it, and even this rather strong sulphuric 

 acid has no action in the cold. With alkalies the hemiacetal forms 

 crystalline salts, which are comparatively stable, since they dissolve 

 in water without decomposition, and can be kept in the dry state for 

 a moderate length of time. The stability of the substance toward 

 alkalies is in marked contrast to its behavior with acids, as it is neces- 

 sary actually to boil it with sodic hydrate in order to convert it into 

 chloranilic acid. The tetraethylacetal can of course form no salts, as 

 it contains no hydroxyl. It is even more stable toward alkalies than 

 the hemiacetal, as sodic hydrate even when boiling or mixed with 

 alcohol does not decompose it. Finally the hemiacetal is amorphous, 

 the acetal crystallizes finely, so that almost the only property which 

 they have in common is their white color. The salts of the hemia- 

 cetals which are not derived from the alkalies are insoluble in water. 

 The dichlordiethoxyquinone dibenzoyldiethylacetal, 



C6Cl2(OC2H5)2(OC2H5)o(OCOC6H5)2, 



also mentioned in the discussion of the constitution of the hemiacetals, 

 was made by the action of benzoyl chloride on the sodium salt of the 

 corresponding hemiacetal suspended in alcohol. In this case the yield 

 is good, about 66 per cent of the theoretical, so that this substance is 



