Iodine → (4-Methoxyphenyl)(3-methylphenyl)methanone

Beteiligte Stoffe

Reaktionsschritte

A 3-neck flask equipped with a condenser, mechanical stirrer and dropping funnel is charged under nitrogen with 1.925 g (79.19 g.a.) of magnesium turnings and enough ether to cover the turnings. A few drops of a solution of 3-bromotoluene (15.79 g, 92.28 mmole) in ether (40 mL) is then added along with a crystal of iodine to initiate the reaction. The remainder of the solution is then added dropwise and the mixture is refluxed until most of the magnesium has disappeared. After cooling, a solution of 4-methoxybenzonitrile (10 g, 75.1 mmole, dried in vacuo over P2O5) is added in one portion. The mixture is refluxed for 2 hours (TLC, no starting material present), cooled (ice bath) and slowly treated with cold water (130 mL) followed by dilute H2SO4 (1:1, v/v, 25 mL). The decomposition of the complex is completed by refluxing the mixture for 4 hours (followed by TLC, 8:2 ether-ethyl acetate). Following stirring overnight at room temperature, the layers are separated and extracted with ether (3×). The extracts are washed with 5% NaHCO3, dried (MgSO4) and evaporated to dryness. The crude material (amber oil, 13.93 g) is purified by flash chromatography (on silica Merck-60, eluted with 8:2 petrolether-ethyl acetate) to provide the title compound as a light yellow oil (12.5 g, 73.5%).

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