402 NAPHTHOIC ACID. 



ful violet precipitates with baryta and lime-water. 

 Excellent dye, very similar to alizarin. 



~ D. ACIDS. 



1. Naphthoic Acid (Menaphthoxylic Add). 

 C ir H 8 2 = C 10 H 7 .CO.OH. 



Formation. From a -cyannaphthalene (p. 393), by 

 boiling with alcoholic potassa, and decomposing the po- 

 tassium salt thus formed with hydrochloric acid. Its 

 ether is also formed by the action of sodium-amalgam 

 on a mixture of monobromnaphthalene and ethyl chlor- 

 carbonate ; its potassium salt, by fusing a mixture of 

 potassium a-sulphonaphthalate with sodium formate. 



Properties. Colorless crystalline needles ; fusing 

 point, 160 ; difficultly soluble in boiling water, easily 

 soluble in boiling alcohol. Heated with baryta, it is 

 resolved into naphthalene and .carbonic acid. 



Barium naphthoate, (C n H 7 2 ) 2 Ba + 4H 2 0, and 

 Calcium naphthoate (C^IPO^Ca + 2H 2 0, are diffi- 

 cultly soluble in water (the calcium salt in 93 parts at 

 15) ; and crystallize in colorless needles. 



Ethyl naphthoate, C 10 H 7 .CO.O.C 2 H 5 . Liquid of an 

 aromatic odor ; boiling point, 309. 



Naphthoyl chloride, C 10 H 7 .COC1. By the action of 

 phosphorus chloride on naphthoic acid. Liquid ; boils 

 at 297.5 ; congeals at a low temperature. 



Naphthoylamide, C 10 H 7 .C0.1srH 2 . Is obtained by 

 the action of ammonia on the chloride ; and by dissolv- 

 ving a-cyannaphthalene in alcoholic soda-ley and pre- 

 cipitating with water. Colorless needles ; fusing point, 

 204 ; insoluble in water, difficultly soluble in alcohol ; 

 sublimable. 



2, Isonaphthoic Acid (^-Naphthoic Acid). 

 C n H 8 2 = C 10 H 7 .CO.OH. 



Is obtained from (3-cyannaphthalene like naphthoic 



