Synthesis of Theophylline

In a 250 mL three-necked reflux apparatus, 23.3 g of 4-amino-1,3-dimethyluracil and 14.7 g of sodium nitrite are dissolved in 120 mL of formamide and heated to 60°C. While stirring vigorously, 24 mL of formic acid is added dropwise within 10 minutes. The suspension is then heated to 100°C, within 10 minutes 4.66 g of sodium dithionite is added in portions with stirring. The reaction mixture is heated at 180-200°C for 3o minutes after the addition. The mixture is then cooled down and filtered. 300 mL of water is added to the filtrate and the residual crude product is recovered using 1oo mL of chloroform. The crude product is then recrystallized from a 1:1 ethanol-water mixture.

Source

Nitrosation of the compound

Heating the mixture at reflux to reduce and cyclize the nitroso derivate of the product

The two fractions of the crude product

The recrystallized product

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