反应详情

To a stirred mixture of hydroquinone (1 mol, 110 g), KOH (1.1 mol, 61 g) in 500 ml of methanol, isopropylbromide (1 mol, 123 g) was added in 2 hours (RT, under N2). The reaction mixture was then stirred at 50° C. for 72 hours. The reaction mixture was cooled to RT and 33% HCl was added (to pH=6). Then CH2Cl2 (500 ml) was added and the mixture extracted with water (7×500 ml) to remove hydroquinone. The organic layer was then extracted with KOH (60 g in 100 ml water). The aqueous layer was extracted twice with CH2Cl2 (200 ml). The solvent of the combined organic layers was evaporated and the residue distilled to give 31g of hydroquinone di-isopropyl ether (boiling point (bp) 78° C./0.026 kPa), in 16%. The aqueous layer was acidified to pH=5 with 33% HCl and extracted with CH2Cl2 (2×200 ml). The combined organic layers were dried over MgSO4 and the solvent evaporated. Distillation of the residue gave 60-85 g (40-55%) of hydroquinone mono-isopropyl ether (bp 90°-100° C./0.026 kPa). 1NMR (CDCl3, ppm(jHz)) : mono-ether: 1.306.0 (6H); 4.396.0 (1H); 5.4(OH); 6.70-6.83AA'BB' (4H); and the di-ether: 1.306.0 (12H); 4.416.0 (2H); 6.81(4H). Hydroquinone di-isopropyl ether (5 mmol) was stirred with acetyl chloride (10 mmol) and 0.1 mmols of SnCl4 for 3 hours (RT) to give hydroquinone diacetate in a yield of more than 95% together with isopropyl chloride.