Using the procedure posted here on the hive, for the preparation of 1,4-dimethoxybenzene, 2,5-dimethoxytoluene was prepared in the following manner:
30,5 g ( 0,3 moles ) of methylhydroquinone was placed in a 250 mL RBF. This was placed in a waterbath at room temperature. 110 mL 20% NaOH was added while stirring. The whole lot dissolved in a matter of seconds, and the mixture turned black/brown within seconds. After a minute 70 mL's of trimethylphosphate was added. The temperature remained constant during the next five minutes. A reflux condensor was attached and the waterbath was slowly heated to a gentle boil over the course of 30 min's. When the waterbath was boiling, the mixture refluxed slightly. This was continued for another hour.
After a hour, the mixture was removed from the waterbath and allowed to cool to almost room temperature. Next, the reaction mixture was added to a seperating funnel, containing 200 mL's of cold water. This was extracted three times with 3*75 mL's of DCM. The first extraction separated fine, but the following two caused heavy emulsion. A bit of NaCl was added, but it did not help a whole lot. Some carefull swirling got rid of the worst emulsion.
The DCM phase was very blackish looking, but two water washes took care of the worst color. The remaning DCM was deeply red in color. The DCM was placed in a large RBF and heated on an oil bath. The DCM was distilled off and the remaining viscious oil was distilled under vacuum. This yeilded a beautifull red-amber colored liquid, which boiled at 130-140 degrees C. The total yeild was 31 grammes(90% molar) of 2,5-dimethoxytoluene.
The reaction gave a very high yeild AND worked on the methyl substituted hydroquinone.
Regards
Bandil