M. Linnemann on Benzpinakone. 533 



when appropriately purified, forms small well-shaped rhombic 

 plates of considerable thickness. It melts at 209° to 210° C. 



When, to an alcoholic solution of benzophenone, sulphuric 

 acid is added and then zinc, a slow disengagement of hydrogen 

 takes place ; and after some time a substance difficultly soluble 

 in alcohol forms, and coats the zinc like a white crust. When 

 this is purified it is obtained as a brilliant white mass, consisting 

 of small needles. It has the formula € 26 H 22 2 , and is derived 

 from two molecules of benzophenone by the assimilation of two 

 of H. It stands to benzophenone just in the same relation as 

 pinakone to acetone. Thus, 



2€ 3 H 6 + H 2 =€ 6 H 14 2 . 



Acetone. Pinakone. 



2€ 13 H 1O 0+H 2 =C 26 H 22 O 2 . 



Benzophenone. 



Linnemann has assigned to it the provisional name benzpinakone. 

 Standing, as regards its composition, between benzophenone 

 and benzhydrole, it is readily converted into either; thus, boiled 

 with a dilute solution of chromic acid, it yields the former, 



e 26 H 22 O 2 + O=2C 13 H 10 O+H 2 O; 

 Benzpinakone. Benzophenone. 



while by the reducing action of sodium-amalgam it is changed 

 into the latter, 



€ 26 H 22 2 + H 2 =2C 13 H 12 0. 

 Benzhydrole. 



Benzpinakone can neither be distilled nor melted without an 

 alteration of its physical properties. In both cases it is con- 

 verted into a body isomeric with benzpinakone, and which is 

 called isobenzpinakone. This is a colourless syrupy liquid which 

 boils at 297°*5, and does not solidify even at —15°. By keep- 

 ing, however, for a few months at the ordinary temperature it 

 becomes solid. Both modifications of benzpinakone have the 

 same chemical reactions. 



The above investigations show that the hydrogen disengaged 

 from an acid solution acts quite differently to that from an alka- 

 line solution. A similar investigation of the behaviour of acro- 

 leine towards zinc and hydochloric acid, by Linnemann*, has 

 shown that the products here obtained also differ from those 

 produced by hydrogen disengaged in alkaline solutions. The 

 action on the acid is very energetic, and requires to be mode- 

 rated by mixing an ice-cold ethereal solution of acroleine with 

 equally cold hydrochloric acid, gradually adding the mixture to 



* Liebig's Annalen, January 1865. 



