Benzoyl benzoic acid from phthalic anhydride

Methyl anthraquinone has been obtained by the oxidation of /3-methyl anthracene by several investigators 1 and material of the same origin, obtained by the benzene-extraction of crude commercial anthraquinone,2 has been fully described. As regards the synthesis from phthalic anhydride and toluene, both the preparation and properties of />-toluyl-o-benzoic acid 3 and the complete synthesis 4 have been the subject of several papers. This acid has also been prepared from o-carbomethoxy benzoyl chloride and toluene.5 The phthalic anhydride synthesis of anthraquinone derivatives in general has received considerable attention. An account of this work, together with extensive references, is given by Barnett.6... 

The oriAo-benzoyl-benzoic acids readily yield anthraquinone and its derivatives (see p. 82). It may be noted that o-benzoyl-benzoic acid itself, with benzene and aluminium chloride, yields phthalophenone the same compound is made directly from phthalic anhydride by increasing the amount of the latter or by adding acetic anhydride. The same holds for p-toluoylbenzoic acid and ditoluoylphthalide. (Am. Soc., 43, 1965 J. C. S., 122, 539.) (For the use of carbomethoxylbenzoyl chlorides and of homophthalic anhydrides in these reactions, see Am. Soc., 43, 1950.)... 

The formation of anthraquinone from phthalic anhydride and benzene by the Friedel and Crafts synthesis is conducted in the presence of aluminum chloride.58 Ortho-benzoyl benzoic acid is first formed and then... 

The o-benzoyl benzoic acid is prepared by mixing phthalic anhydride with an excess of benzene and adding to an amount of aluminum chloride equimolar to the anhydride used. This mixture is maintained at a temperature of 35° C. in a lead lined kettle, jacketed for steam heating, for about half an hour. The temperature is then slowly raised to the boiling point of benzene and maintained until hydrochloric arid is no longer evolved. Benzene is removed by distillation with steam, the o-benzoyl benzoic arid dried and converted to anthraquinone by treatment with 95 to 98 per cent sulfuric acid at a temperature of from 110° to 150° C. for three-quarters to one hour. The anthraquinone thus fomied is recovered from the concentrated sulfuric acid by careful dilution of the acid with water or treatment with steam to obtain large crystals to facilitate filtration, removal of acid, and washing. 

Phenylacetic acids have been prepared from 2,2-dichlorostyrenes by sequential hydroboration and oxidation (Cr03-H2S04) of the intermediate trialkyl borane, and benzoyl benzoic acids (8), not readily available by other routes, have been obtained" in good yield by treatment of phthalic anhydride with aryl-lithiums at — lOO C. Syntheses of some bicyclo [1,1,0] butane-l-carboxylic acids (9) and a range of cyclopropane-1-carboxylic acids [(10) and (II)] have been described. 1-Hydroxy-cyclopropanecarboxylic acids (13) have been prepared from the hydroxy-cyclobutanone derivatives (12), following bromination and hydrolysis. 

Benzoic acid can also be produced commercially from benzotrichloride or phthalic anhydride. Benzotrichloride, produced by chlorination of toluene, is reacted with 1 mole of benzoic acid to yield 2 moles of benzoyl chloride. The benzoyl chloride is then converted to 2 moles of benzoic acid by hydrolysis. Yield is 75-80%. 

---

See also in sourсe #XX -- [ ]

---