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Synthesis of N-Phenylanthranilic acid under Ullman conditions; N-Phenylanthranilic acid

SyntheticPage 954
Submitted Nov 13, 2021, published Nov 15, 2021
Robert Smith (, Sarah Brennan ()
A contribution from Smith Group

			Reaction Scheme: Synthesis of <em>N</em>-Phenylanthranilic acid&nbsp;under&nbsp;Ullman conditions

Chemicals Used

Aniline (Fisher) 
2-Bromobenzoic acid (Fisher) 
Copper bronze (Sigma Aldrich) 
N',N'-DMF (Fisher) 
Hydrochloric acid (Fisher) 
Potassium carbonate (Fisher) 


To a quick-fit conical flask, equipped with condenser apparatus, aniline (0.95 mL, 10 mmol), 2-bromobenzoic acid (2.01 g, 10 mmol), potassium carbonate (3.4 g, 25 mmol), copper bronze (0.256 g, 4mmol) and DMF (40 mL) was added*. The reaction mixture was heated to reflux with constant stirring for 4 hours. Upon cooling, the solution poured over ice with stirring, then filtered through celite**. A minimum amount of concentrated hydrochloric acid was added dropwise to the filtrate to obtain pH=4***. The precipitate obtained was isolated at the pump to yield 2-(phenylamino) benzoic acid (1.40g, 67%) as a dark green solid.  

Author's Comments

* a 100ml quickfit flat bottom flask with condenser tube was used. 

** Temperature was maintained using the sensor on the hotplate. Constant stirring was maintained using a stirrer bar and controlled via the hot plate. The reaction did not require dry/inert conditions and took place in open air. 

*** Indicator paper was used to determine pH. 


1H NMR (300 MHz, DMSO) δ 12.89 (s, 1H), 7.95 (s, 1H), 7.83 (d, J = 7.7 Hz, 1H), 7.56 (t, J = 7.8 Hz, 1H), 7.35 (t, J = 7.9 Hz, 2H), 7.27 (t, J = 7.6 Hz, 1H), 7.08 (t, J = 7.3 Hz, 1H), 7.01 (d, J = 8.2 Hz, 1H), 6.90 (d, J = 8.7 Hz, 2H). 13C NMR (75 MHz, DMSO) δ 167.01, 157.92, 155.26, 134.04, 131.84, 130.35, 124.97, 124.48, 123.31, 121.48, 118.04. IR: 3332.34, 2637.37, 1655.04, 1575.30, 1260.82, 889.68. LC-MS m/z: 214.35 [M+].  

Lead Reference

Litchfield, V.J., Smith, R.B., Franklin, A.M., Davis, J., Synthesis of acridine-quinone systems - A potential electrochemical fluorescent switch
(2008) Synthetic Communications, 38 (20), pp. 3447-3455. 

Supplementary Information

e.g. Actual NMR spectra (as images or jdx files for interactive spectra), photographs of apparatus, TLC’s or crystals or videos. Please contact the ChemSpider team ( for help with this.
N-Phenylanthrinilic acid - LCM (2-phenylamino benzoic acid LCMS.pdf)
N-Phenylanthrinilic acid - 1H (sarah brennan amino benzoic acid rerun.10.fid.pdf)
N-Phenylanthrinilic acid - 13C (amino benzoic acid c13.pdf)
N-Phenylanthrinilic acid - 135 (amino benzoic acid dept135.pdf)
N-Phenylanthrinilic acid - IR (phenyl amino benzoic IR.pdf)

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Keywords: amines, aromatics/arenes, carboxylic acids, nucleophilic, substitution

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