OP ARTS AND SCIENCES. 151 



EN=C ' 



by the elimination of alkylckloride, R'Cl, into isonitriles, EN=C= 

 (pp. 127, 128). 



In this ca.se two carbon atoms bound singly to each other are 

 torn apart, which shows how strong a tendency must exist for a 

 decomposition in this direction. A similar reaction has already 

 been observed by myself in the case of dibenzoyl, diacetyl, and 

 dicarboxyl-acetacetic ether.* 



That chloralhydrate and glyoxylic and mesoxalic acid contain 

 two hydroxy 1 groups bound to the same carbon atom is pretty gen- 

 erally regarded as proved. Very recently Zincke and Arustf have 

 shown that tetrachlor-o-diketohydronaphthaline forms hydrates and 

 alcoholates, where the water and alcohol respectively cannot be 

 present as crystal water. 



There exist already a number of examples in chemical litera- 

 ture where a substance containing carbonyl groups attains thereby 

 acid properties. Thus, for example, triquinoyl, j C 6 6 + 8 H 2 0, 

 and leuconic acid, C 5 5 + 4 H 2 0, of which the last named has been 

 especially studied by Nietzki and Benckiser.§ These substances, 

 being strong acids, cannot contain all the water as crystal 

 water, but they are to be regarded as hydroxylated compounds ; 

 C 6 6 + 8 H 2 0, e. g., is very probably dodekoxyhexarnetlrylene, 

 C 6 (OH) 12 + 2H 2 0. 



In a like manner diacetyl, CH 3 -CO-CO-CH 3 , which was discov- 

 ered almost simultaneously by v. Pechmann || and by Fittig,!" pos- 

 sesses marked acid properties. It can be separated completely 

 from alcohol by concentrating a sodic carbonate solution of it on a 

 water bath.** Diacetyl itself forms hydrates and alcoholates, de- 

 composed by sulphuric acid, which have as yet not been further 

 studied.** It follows, therefore, that this substance by taking up 

 water becomes an acid stronger than carbonic acid: it cannot be 

 decided yet whether the acid resulting has the formula 



* Ann. Chem. (Liebig), CCLXVI. 101, 105, 107. 

 t Ibid., CCLXVII. 329. 



t Nietzki and Benckiser, Ber. d. Chem. Ges., XVIII. 504, 1842. 

 § Ber. d. Chem. Ges., XIX. 301. 

 || Ibid., XX. 3163, 3213. 

 1 Ibid., XX. 3184. 

 ** Ibid., XXI. 1411, 1412, v. Pechmann. 



