ACETENYLBENZENE. 379 



the solution on the subsequent addition of sulphuric 

 acid. Yellowish, lustrous prisms or laminae; but 

 slightly soluble in cold water, more easily in hot water, 

 very easily in alcohol. The aqueous solution reduces 

 a silver solution when warm, but does not change an 

 alkaline solution of copper; becomes intensely green 

 on the addition of iron chloride, and this color changes 

 to dark red if sodium carbonate now be added. When 

 subjected to dry distillation, it yields pyrocatechin 

 (p. 305) ; when fused with potassium hydroxide, proto- 

 catechuic (p. 356) and acetic acids. It combines with 

 nascent hydrogen, forming hydrocaifeic acid (p. 360). 



THIRD GROUP. 



Acetenylbenzene (Phenylacetylene.) 

 C 8 H 6 = C 6 H 5 .C:CH. 



Is produced by heating cinnamene bromide, a -brom- 

 cinnamene and acetopheiione chloride (C 6 H 5 .CC1 2 .CH 3 , 

 from acetophenone (p. 335) with phosphorus chloride) 

 with alcoholic potassa to 120 ; by heating phenyl- 

 propiolic acid with water to 120; and by subjecting 

 barium phenylpropiolate to dry distillation. Colorless 

 liquid ; boiling point, 139-140. Its dilute alcoholic 

 solution gives a bright-yellow flocky precipitate, 

 (C 8 H 5 ) 2 Cu 2 , with an ammoniacal solution of copper; 

 a white precipitate, (C 8 H 5 Ag) 2 -f Ag 2 0, with an ammo- 

 niacal solution of silver. Hydrochloric acid separates 

 the acetenylbenzene from both compounds. When 

 sodium is added to its ethereal solution, it yields a 

 white sodium compound, C 8 H 5 ^"a, which in contact 

 with air takes fire and gradually goes out. 



Diacetenylphenyl, C 16 H 10 . Is formed when the 

 copper-compound of acetenylbenzene is violently shaken 

 with alcoholic ammonia, the air being allowed to have 

 free access. Long, brittle, colorless, and transparent 

 needles ; fusing point, 97 ; insoluble in water ; easily 

 soluble in alcohol and ether. 



