Methanol → 1,3-Dimethyl 1,3-cyclopentanedicarboxylate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A 5-L, 3-neck, round bottom flask was equipped with a mechanical stirrer, a J-KEM temperature controller, and a reflux condenser. The flask was charged with cyclopentane-1,3-dicarboxylic acid (357 g, 2.262 mol) and methanol (1.75 L). The solution was cooled to 7° C. using an ice/water bath. Concentrated sulfuric acid (70 mL) was added dropwise over 30 min resulting in an exotherm up to 12° C. The reaction mixture was heated to reflux and stirred for 16 h when TLC analysis (10% methanol/ethyl acetate) indicated that the reaction was complete. The reaction mixture was concentrated, redissolved in methyl tert-butyl ether, and washed with saturated aqueous sodium bicarbonate (2×150 mL) and brine (2×150 mL). The organic layer was dried over sodium sulfate, filtered, and concentrated. The resulting clear oil was dissolved in hexane (2 L) and treated with a 2 N aqueous sodium hydroxide solution (950 mL) until the pH˜10. The layers were separated and the aqueous layer was extracted with hexane (4×1 L). The organic layers were combined, dried over sodium sulfate, filtered, and concentrated to provide 360 g (100%) of dimethyl cyclopentane-1,3-dicarboxylate as a clear oil. 1H NMR (500 Hz, CDCl3) δ ppm 3.67 (s, 6H), 2.75-2.83 (m, 2H), 2.20-2.26 (m, 1H), 2.05-2.12 (m, 1H), 1.90-2.0 (m, 4H).

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