BENZOIC ACID. 329 



ble in water than the isomeric compounds. Fuses 

 under boiling water. 



Metachlorbenzoic acid. Is produced from ben- 

 zoic acid by heating with hydrochloric acid and potas- 

 sium chlorate or antimony chloride or calcium hypo- 

 chlorite ; by the decomposition of chlorhippuric with 

 hydrochloric acid ; by boiling cinnamic acid with a solu- 

 tion of bleaching lime ; and by oxidation of meta-chlor- 

 toluene. Colorless needles, that fuse at 152, and sub- 

 lime without decomposition. Very difficultly soluble 

 in cold water. 



Parachlorbenzoic acid (Chlordracylic acid), formed 

 by the oxidation of parachlortoluene. Sublimes in 

 colorless scales, that fuse at 236-237. 



Dichlorbenzoic acid, C 6 H 3 C1 2 .CO.OH. Is produced 

 from rneta- and parachlorbenzoic acids by boiling with 

 a solution of bleaching lime, or by treating with anti- 

 mony chloride ; by oxidation of dichlortoluene, dichlor- 

 benzyl chloride, and dichlorbenzal chloride (p. 275) 

 with chromic acid; and by heating dichlorbenzotri- 

 chloride (p. 275) with water. Colorless needles fusing 

 at 201-202. 



Trichlorbenzoic acid, C 6 H 2 CRCO.OH, and Tetra- 



chlorbenzoic acid, C 6 HC1 4 .CO.OH, are obtained by heat- 

 ing tri- and tetrachlorbenzotrichloride (p. 275) with 

 water to 260-280. Both crystallize in colorless nee- 

 dles ; the former fuses at 163, the latter at 187. 



Metabrombenzpic acid, CMPBrO 2 , is formed by 

 heating benzoic acid with bromine and water to 130- 

 160. Colorless needles ; fuse at 152-153 ; but slightly 

 soluble in water. Parabrombenzoic add (Bromdracylic 

 acid), C 7 H 5 Br0 2 , is obtained by the oxidation of para- 

 bromtoluene. -Small, colorless needles, almost insoluble 

 in cold water. Fusing point, 251. 



Dibrombenzoic acid, C 7 H 4 Br 2 2 (fusing point, 

 223-227), TribrombenzQic add, C 7 H 3 Bi^0 2 (fusing 



28* 



