domethane (4.98 ml, 9.99 mmol) was added dropwise to a solution of hydroquinone (4.00 g, 36.33 mmol) and KOH (8.32 g, 148.30 mmol) in 75 ml of DMSO. The reaction mixture became dark and was stirred at r.t. for 1 h at 25°C. The reaction mixture was neutralized by adding an aqueous saturated solution OfNH4Cl. The product was extracted with dichloromethane (3 x 50 mL). The organic phases were washed several times with water (5 x 150 mL) to eliminate DMSO, then dried over anhydrous Na2SO4. The solvent was evaporated at reduced pressure. A white solid was isolated (4.87 g, yield 97percent).
Please see the following paper in which an O-alkylation reaction of hydroquinone with excess methanol was carried out by using alkaline metal ion-exchanged zeolite catalysts at various phases of methanol in a slurry type reactor.