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A solution of 4-isobutylbenzoic acid (5.00 g, 28.0 mmol) in CH2Cl2 was cooled in an ice bath and treated with oxalyl chloride (5 mL) and DMF (1 drop). The mixture was warmed to room temp and stirred 1 h. The volatiles were removed in vacuo to give the crude acid chloride which as dissolved in benzene (50 mL). Aluminum chloride (4.49 g, 33.3 mmol) was added and the mixture was heated to reflux for 3.5 h. The mixture was cooled to room temp and then poured onto ice (ca. 100 g). The mixture was extracted with EtOAc (3×100 mL) and the combined organic extracts were washed with ½ satd aqueous NaHCO3 (100 mL), dried (Na2SO4), filtered and evaporated in vacuo. The resulting residue was purified by silica gel chromatography (elute with 10:1 hexane/EtOAc) to give 4-isobutylbenzophenone (5.48 g, 81%). 1H NMR (CDCl3) 7.75 (m, 4H), 7.53 (d, 1H), 7.47 (t, 2H), 7.23 (d, 2H), 2.53 (d, 2H), 1.91 (m, 1H), 0.92 (d, 6H).

1. customThe volatiles were removed in vacuo
2. customto give the crude acid chloride which
3. temperaturethe mixture was heated
4. temperatureto reflux for 3.5 h
5. temperatureThe mixture was cooled to room temp
6. additionpoured onto ice (ca. 100 g)
7. extractionThe mixture was extracted with EtOAc (3×100 mL)
8. washthe combined organic extracts were washed with ½ satd aqueous NaHCO3 (100 mL)
9. dry with materialdried (Na2SO4)
10. filtrationfiltered
11. customevaporated in vacuo
12. customThe resulting residue was purified by silica gel chromatography (elute with 10:1 hexane/EtOAc)