Synthesis of 2-(4-methylbenzoyl)benzoic acid

Preparation of 2-(4-methylbenzoyl)benzoic acid (o-(p-toluoyl)benzoic acid)

Preparation of 2-(4-methylbenzoyl)benzoic acid (o-(p-toluoyl)benzoic acid)

Preparation of 2-(4-methylbenzoyl)benzoic acid (o-(p-toluoyl)benzoic acid)

The Friedel and Crafts reaction is carried out in a 500 ml round-bottomed flask equipped with a short condenser. A trap for collecting the hydrogen chloride liberated is connected to the top of the condenser by means of a piece of rubber tubing sufficiently long to make it possible to heat the flask on the or to plunge it into an ice bath. The most convenient form of trap is a suction flask half-filled with water and with a delivery tube inserted to within 5 mm of the surface of the water. 15 grams of phthalic anhydride and 75 ml of pure toluene are placed in the flask and this is cooled in an ice bath. 30 grams of anhydrous aluminum chloride are added, the condenser and trap are connected, and the flask is shaken well and warmed for a few minutes by the heat of the  hand. If the reaction does not start, the flask is warmed very gently. At the first sign of vigorous boiling or evolution of hydrogen chloride, the flask is held over the ice bath in readiness to immerse in ice if the reaction becomes too vigorous. This gentle, cautious heating is continued until the reaction is proceeding smoothly enough so that the mixture may be refluxed by heating. The refluxing is continued for one-half hour with constant stirring. It is generally noted that, after about 5 minutes of refluxing, the aluminum chloride nearly all dissolves and the colorless addition product suddenly separates. At the end of the time specified the flask is cooled well in ice and the aluminum compound is decomposed by the cautious addition of ice and then water. While shaking the flask in the ice bath, small pieces of ice are added, one at a time waiting after each addition until the last piece has reacted. Too rapid addition of ice may cause very vigorous boiling. When the ice no longer produces much reaction and about 100 ml has been added, 20 ml of concentrated hydrochloric acid are added, together with enough water to make the flask half full. The excess toluene is then removed by steam distillation, and it is separated from the water layer. The 2-(4-methylbenzoyl)benzoic acid is left as an oil which partially solidifies on cooling in ice. The aqueous solution containing aluminum chloride is decanted through a suction funnel, the residue is washed once with water, and the material collected is returned to the flask. In order to remove traces of aluminum, the acid is dissolved in sodium carbonate solution. This is done by adding 75 ml of 10% sodium carbonate solution and enough water to half fill the flask, and then passing in steam as in a steam distillation until all of the solid material except particles of aluminum oxide or aluminum hydroxide has become dissolved. The solution of the sodium salt of 2-(4-methylbenzoyl)benzoic acid is then cooled well in ice, stirred with 1 g of activated charcoal, filtered by suction, and placed in a 600 ml beaker. The acid is then precipitated by cautious neutralization with hydrochloric acid, adding a little at a time and stirring well. The 2-(4-methylbenzoyl)benzoic acid usually separates as an oil, but it soon solidifies on stirring and cooling. The crude 2-(4-methylbenzoyl)benzoic acid usually separates in a partly hydrated condition and it is best to dry it in a dish on the steam bath. A yield as high as 96% of the theoretical amount can be obtained and the crude product, which melts at 138-139° C, is sufficiently pure for most purposes. Pure crystals melting at 139-140° C can be obtained from benzene or toluene.

Experiments in Organic Chemistry, L. F. Fieser, 187, 1941


2-(4-methylbenzoyl)benzoic acid



InChI Key


Canonical SMILES


Depositor-Supplied Synonyms

2-(4-Methylbenzoyl)benzoic acid, 85-55-2, 2-(p-Toluoyl)benzoic acid, Benzoic acid, 2-(4-methylbenzoyl)-, 2-(p-Toluyl)benzoic acid, o-(p-Toluoyl)benzoic acid, Benzoic acid, o-(p-toluoyl)-, 2-p-Toluoylbenzoic acid, p-Toluoyl-o-benzoic acid, 4′-Methylbenzophenone-2-carboxylic acid, 2-[(4-methylphenyl)carbonyl]benzoic acid, CHEMBL83270, 2-(4-METHYLBENZOYL)BENZOIC ACI D, NSC11224, AC1Q2JMC, AC1Q2JNJ, Maybridge1_003330, ACMC-209q6p, UNII-4DN9G70PQF, AC1L25NI, 4DN9G70PQF, Oprea1_759926, SCHEMBL503364, methylbenzoylbenzenecarboxylicacid, CTK6B7652, HMS550P08, ICQOWIXIHDDXDI-UHFFFAOYSA-N, MolPort-000-632-041, BB_SC-6785, 2-(4-Methyl-Benzoyl)Benzoic Acid, 2-(4-Methyl-benzoyl)-benzoic acid, EINECS 201-614-3, ANW-38207, BBL013167, NSC 11224, NSC-11224, SBB038602, STK398304, AKOS000119491, Benzoic acid, o-(p-toluoyl)- (8CI), MCULE-7014572126, NE10808, RP13738, 4-Methylbenzophenone-2′-carboxylic Acid, 2-(4-methylbenzoyl)benzenecarboxylic acid, AN-42317, KB-87568, DB-030194, KB-163067, TR-026727, UNM-0000306020, FT-0608920, ST45107046, UNM000011084701, 5Y-1180, AG-205/01795008, S14-0942, 3B3-061199, T0514-7065

Removed Synonyms

o-(p-Toluyl)-benzoic acid, CID66563, T0308, 7148-03-0

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