Sodium Hydroxide → HCID 10934421, compound

Participants

Reaction Steps

In a 5 L 3-necked flask fitted with a mechanical stirrer and a condenser with a drying tube were placed 2.2 L of pyridine and 8-cyclopropyl-3-propyl-2-thio-xanthine (220 g, 0.88 mol). Phosphorus pentasulfide (236 g, 1.06 mol) was added and the mixture was heated under reflux for 5 hours and stored overnight at room temperature. The reaction mixture was cooled to 5-10° and 3 N aqueous sodium hydroxide (770 ml) was added over 1.5 hours with stirring. Stirring was continued for 30 minutes after removal of the cooling bath and the precipitated product was collected by suction filtration. The filter cake was washed successively with pyridine (300 ml) and four 300 ml portions of tetrahydrofuran. The solvents are evaporated in vacuo and the solid residue was stirred with water (750 ml), filtered and washed with water. The crude product was dissolved in 1.7 L of 1 N sodium hydroxide and stirred with 15 g of Darco G-60. The charcoal was filtered and the treatment was repeated with a fresh portion of charcoal. The solution was acidified to pH 1.5 with 6 N hydrochloric acid and the pale yellow precipitate was collected. The solid was dissolved again in 1.7 L of 1N sodium hydroxide and treated successively with two portions of charcoal as above. The solution was acidified and the precipitate was collected and washed with water. After drying to constant weight at 54° C. under vacuum, there was obtained 128 g (56%) of the title compound, mp over 245° C.

Provenance & Evidence