270 BENZENE. 



Chlor-, Brom-, lodo-, Nitro-, and Amidosulpho- 

 benzolic acid, are produced by dissolving the mono- 

 substitution-products of benzene in weak fuming sul- 

 phuric acid. They all belong to the para-series. 



Benzenesulphurous acid, C 6 H 5 .S0 2 II. The sodium 

 salt is produced by treating an ethereal solution of 

 sulphobenzolchloride with sodium-amalgam. Hydro- 

 chloric acid separates the free acid from this. Large, 

 colorless prisms of a high lustre. Difficultly soluble 

 in cold water, easily soluble in hot water, alcohol, and 

 ether. Fuses at 68-69, and is decomposed at a higher 

 temperature. With chlorine or bromine it yields sul- 

 phobenzolchoride or bromide ; and, in contact with the 

 air, is transformed slowly into sulphobenzolic acid, 

 rapidly by means of oxidizing agents. Monobasic 

 acid. 



Paradisulphobenzolic acid, C 6 H 4 (S0 2 .OH) 2 , is 

 formed by heating sulphobenzolic acid or benzonitrile 

 with fuming sulphuric acid. The barium salt, C 6 H 4 . 

 S 2 6 Ba-f 1JH 2 0, forms easily soluble microscopic crys- 

 tals. 



Paradisulphobenzolchloride, C 6 H 4 (S0 2 C1) 2 . Is 



produced by the action of phosphorus pentachloride on 

 sodium paradisulphobenzolate. Large, colorless crys- 

 tals. Fusing point, 62. 



Diphenyl, C 12 H 10 . Is formed when sodium is al- 

 lowed to act upon a solution of monobrombenzene in 

 ether or benzene. Is also produced when benzene- 

 vapor is passed through an ignited tube ; by heating 

 potassium benzoate with phenol potassium; and in 

 small quantity, together with benzene, by heating ben- 

 zoic acid with lime. Large, colorless, crystalline 

 laminae, insoluble in water, easily soluble in hot alco- 

 hol. Fuses at 70.5, and boils at 239-240. 



