328 BENZOIC ACID. 



with violence at a higher temperature. Monobasic 

 acid ; yields crystallizing salts. 



Tribenzhydroxylamine, (C 6 H 5 .CO) 2 .N.O(C 6 H 5 .CO). 



Is formed by the action of benzoyl chloride on dry hy- 

 droxylamirie hydrochlorate, which is dissolved in a 

 hydrocarbon boiling at 110 ; also when potassium di- 

 benzhydroxamate is heated with benzoyl chloride. 

 Lustrous prisms ; fusing point, 141-142 ; decomposes 

 at 190 ; insoluble in water, ether, and benzene ; very 

 difficultly soluble in cold alcohol, much more readily 

 in hot alcohol. 



Benzole anhydride, (C 7 H 5 0) 2 0. Is produced by 

 the action of benzoyl chloride on sodium benzoate ; and 

 by heating 6 parts dry sodium benzoate with 1 part 

 phosphorus oxichloride to 150. The salts (sodium 

 metaphosphate and sodium chloride), that are formed 

 are extracted with water. Oblique prisms, insoluble 

 in cold water, soluble in alcohol, forming a neutral so- 

 lution. Fuses at 42, and distils at 310. "When boiled 

 with water, it is gradually converted into benzoic acid ; 

 and when heated in hydrochloric acid gas, is decom- 

 posed, yielding benzoic acid and benzoyl chloride. 



Substitution-products of benzoic acid. Those 

 substitution-products which are formed by the direct 

 action of chlorine, bromine, etc., on benzoic acid, be- 

 long to the meta-series ; the isomeric ortho-compounds 

 are obtained from salicylic acid ; the para-corn pounds 

 by oxidation of the para-substitution-products of 

 toluene. By the latter method the meta-compounds 

 can also be obtained, but not the ortho-compounds 

 (cf. p. 274). 



Orthochlorbenzoic acid (Chlorsalylic acid), 

 C'IFCIO 2 = C 6 H 4 C1.CO.OH. The chloride (chlorsalyl 

 chloride), C 6 H 4 C1.COC1 (a colorless oil, boiling at 240), 

 is produced by the action of phosphorus chloride on 

 salicylic acid. This yields the acid when treated with 

 water. Needles, that fuse at 137 ; more readily solu- 



