Preparation of 1 4 dimethoxybenzene
1 4 dimethoxybenzene: The 1 mole of hydroquinone (benzene-1,4-diol, quinol) is treated rapidly with stirring, in a three-necked flask provided with a reflux condenser, stirrer, internal thermometer, and dropping funnel, with 2.5 mole of 10% sodium hydroxide. With vigorous stirring, 2 mole of dimethyl sulfate is added in such a way that the temperature remains below 40° C (water cooling).
To complete the reaction and to destroy unchanged dimethyl sulfate, the mixture is then heated for 30 min on a boiling water bath. After cooling the solid reaction product is isolated by filtration, washed with water, and recrystallized from alcohol or vacuum distilled b.p. 109°C/20mm. Unchanged hydroquinone can be recovered by acidifying the aqueous reaction solution and the wash water and extracting them with ether. The yield of 4-methoxyphenol is 95%, b.p. 213 °C; b.p. 109°C/20mm; m.p. 54-56 °C.
Organicum. Practical Handbook of Organic Chemistry, by Heinz Becker, Werner Berger and Günter Domschke, Addison-Wesley Pub. Co, 206-207, (1973)