Hydrochloric Acid → 5-(2',4'-Dichlorobenzoyl)-1-methylpyrrole-2-acetonitrile

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Reaction Steps

To a suspension of 16.6 g. (0.125 mole) of aluminum chloride in 60 ml. 1,2-dichloroethane is added 26.2 g. (0.125 mole) of 2,4-dichlorobenzoyl chloride. The resulting solution is added slowly to a solution of 15 g. (0.125 mole) of 1-methylpyrrole-2-acetonitrile in 60 ml. 1,2-dichloroethane while cooling externally with an ice bath. After the addition is complete, the mixture is stirred for 40 minutes at room temperature followed by heating at reflux for 3 minutes. It is then poured into ice acidified with dilute hydrochloric acid. The organic phase is separated and washed successively with N,N-dimethyl-1,3-propanediamine, 3N hydrochloric acid, and saturated sodium chloride solution. It is then dried over magnesium sulfate and the solvent evaporated. The resulting red oily residue is chromatographed on a column packed with neutral alumina and eluted with benzene and ether. The first compound-bearing fractions upon evaporation yield a white solid, 5-(2′,4′-dichlorobenzoyl)-1-methylpyrrole-2-acetonitrile, which is purified by recrystallization from methanol, m.p. 129-130° C. Analysis: Calcd. for C14H10Cl2N2O: N, 9.56%. Found: N, 9.51%.

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