Potassium o-chlorobenzoate

A mixture of 2-(4-aminophenyl)propionic acid (52.2 g), potassium o-chlorobenzoate (61.5 g), potassium carbonate (43.6 g) and copper powder (0.3 g) in amyl alcohol (620 ml) is heating under reflux for 16 h. The major proportion of the solvent is then removed by steam distillation. The residual aqueous solution is treated with decolorising charcoal (20.0 g) and acidified with 4 N sulfuric acid (220 ml). The cream product which crystallises is dissolved in diethyl ether (500 ml). 

Potassium o-chlorobenzoate 6>-Chlorobenzoic acid (76-78%) When two alkyl groups are present on the ring, both are oxidized. 

In a 1 litre round-bottomed flask, equipped with an air condenser, place a mixture of 44 g. of o-chlorobenzoic acid (Section IV,157) (1), 156 g. (153 ml.) of redistilled aniline, 41 g. of anhydrous potassium carbonate and 1 g. of cupric oxide. Reflux the mixture in an oil bath for 2 hours. Allow to cool. Remove the excess of aniline by steam distillation and add 20 g. of decolourising carbon to the brown residual solution. Boil the mixture for 15 minutes, and filter at the pump. Add the filtrate with stirring to a mixture of 30 ml. of concentrated hydrochloric acid and 60 ml. of water, and allow to cool. Filter off the precipitated acid with suction, and dry to constant weight upon filter paper in the air. The yield of iV-phenylanthranilic acid, m.p. 181-182° (capillary tube placed in preheated bath at 170°), is 50 g. This acid is pure enough for most purposes. It may be recrystaUised as follows dissolve 5 g. of the acid in either 25 ml. of alcohol or in 10 ml. of acetic acid, and add 5 ml. of hot water m.p. 182-183°. 

N-Phenylanthranilic acid may be prepared by the action of aniline upon o-chlorobenzoic acid in the presence of anhydrous potassium carbonate and a little copper oxide ... 

Cognate preparations, p-Chlorobenzoic acid. Proceed exactly as for o-chlorobenzoic acid. Use 1250 ml of water, 50 g (0.4 mol) of p-chlorotoluene (Expt 6.71) and 75 g, 37.5 g and 37.5 g (0.95 mol total) of potassium permanganate. When the oxidation is complete, steam distil the mixture to recover any unreacted p-chlorotoluene (3-4 g). Filter the reaction mixture from hydrated manganese dioxide and wash the precipitate with two 100 ml portions of water. Precipitate the p-chlorobenzoic acid in the filtrate (1) by the addition of 75 ml of concentrated hydrochloric acid. Filter the cold solution with suction, wash with cold water and dry in an oven at 100 °C. The yield of p-chlorobenzoic acid, m.p. 234-235 °C, is 55 g (89%). Recrystallisation from hot water raises the m.p. to 238-239 °C. 

N,N -Carbonyldiimidazole (1.65 g, 10 mmol) was added to a solution of o-chlorobenzoic acid (1.57g, lOmmol) in dimethylformamide (10ml) held under nitrogen, and the mixture was stirred for 1 hour at 40 °C. t-Butyl alcohol (1.48 g, 20mmol) and DBU (l,8-diazabicyclo[5.4.0]undec-7-ene, 1.52 g, 10 mmol) were added and the mixture stood for 24 hours at 40 °C. Ether (100 ml) was then added, and the solution was washed with 10 per cent hydrochloric acid (20 ml), water (20 ml), aqueous potassium hydrogen carbonate (20 ml) and dried over anhydrous sodium sulphate. The solvent... 

A mixture 31.3 g of o-chlorobenzoic acid, 32.2 g of trifluoromethyl-m-aminobenzene, 3 g of copper powder, 13.8 g of waterless potassium carbonate and 100 ml amyl alcohol was refluxed for 4 hours. To the cooled mixture was added 25 ml of 10 N solution NaOH and the mixture was concentrated and filtrated. Addition to the filtrate hydrochloric acid and water give a sediment of 2-((3-trifluromethyl)phenyl)aminobenzoic acid. After recrystallization from hexane 2-((3-trifluromethyl)phenyl)aminobenzoic acid have melting point 134-136°C. 

Specific diarylarnines not easily obtained by the above methods can be prepared by the Ullmann (29) and Chapman (30) reactions. For example, y -chloroaruline reacts with o-chlorobenzoic acid in the presence of potassium carbonate and a catalytic amount of a copper salt to give 2-[(3-chlorophenyl)amino]benzoic acid [13278-36-9] which is then decarboxylated on heating to 3-chlorodiphenylamine [101-17-7]. 

It may be prepared by the condensation of o-chlorobenzoic acid with 2, 3-xylidine in the presence of potassium carbonate to give the potassium salt of mefenamic acid, which on treatment with hydrochloric acid yields the official compound. 

The cyclodehydration of o-phenoxybenzoic acids has been widely used to synthesize xanthones carrying variety of substituents. An Ullmann reaction provides a useful route to the required acids a 2-chlorobenzoic acid and a phenol react in an inert solvent such as nitrobenzene in the presence of copper bronze and potassium carbonate (53JCS1348). In a modified procedure sodium methoxide is used without solvent at 200 °C (79JA665). Cyclization is accomplished in concentrated sulfuric acid or in acetyl chloride containing a little sulfuric acid (61JCS2312). 

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