BENZOIC ACID. 329 



blc in water than the isomeric compounds. Fuses 

 under boiling water. 



Metachlorbenzoic acid. Is produced from ben- 

 zoic acid by beating 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-ehlor- 

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

 lime without decomposition. Very difficultly soluble 

 in cold wafer. 



Parachlorbenzoic acid (Chlordracylic acid), formed 

 by the oxidation of parachlortoluene. Sublimes in 

 colorless scales, that fuse at 236-237. 



Diehlorbenzoic acid, C 6 1FC1 2 .CO.OH. Is produced 

 from meta- 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 CKCO.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. 



Metabrombenzoic acid, C r H 5 Br0 2 , is formed by 

 heatino- benzoic acid with bromine and water to 130- 

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

 soluble in water. Parabrombenzoic acid (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), Tribrombenztic add, C 7 H 3 Br 3 3 (fusing 



28* 



