1,8-Dichloroanthraquinone → 1,8-Dimethoxyanthraquinone

Participants

Reaction Steps

A 5-liter round-bottom flask equipped with an overhead stirrer, thermocouple, and reflux condenser with a nitrogen/vacuum outlet was charged with 1200 mL of tetrahydrofuran, 138.5 grams of 1,8-dichloroanthraquinone, and 35.6 grams of 18-crown-6. This solution was deoxygenated, stirred under nitrogen, and heated until a clear solution was obtained. A solution of 165.0 grams of sodium methoxide in 1000 mL of methanol (prepared from sodium metal) was then added over a period of 30 min. The reaction mixture was heated at reflux for 24 hours, at which time TLC (silica gel, 1:1 EtOAc/toluene) indicated that the reaction was complete. The reaction was cooled overnight in an ice bath and the crystallized product isolated by filtration (82% crude yield). This material was recrystallized from 1000 mL of toluene to afford 1,8-dimethoxyanthraquinone in an overall yield of 50%.

Provenance & Evidence