2892-62-8

2892-51-5

71-36-3

2892-62-8

General procedure for the synthesis of di-n-butyl squarate from squaric acid (1) (2.00 g, 17.54 mmol) and n-butanol: Squaric acid (1) was dissolved in n-butanol (50 mL) and the reaction was carried out under stirring conditions at reflux for 3 hours. After completion of the reaction, the mixture was cooled in an ice bath, followed by the addition of diethyl ether (Et2O, 50 mL). The mixture was washed sequentially with cold distilled water, cold saturated aqueous NaHCO3 solution and cold distilled water. The organic layer was separated and dried with anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure to give the brown oily product di-n-butyl squarate (2.92 g, 74% yield). The product was chromatographically pure and could be used in subsequent reactions without further purification.