Phosgene was passed in a fine stream into a suspension of finely ground glycine (15 g) in dry dioxane (750 mL) at 45–50 ℃ with efficient agitation. A clear solution was obtained after 5 h. This solution was filtered to remove unreacted glycine (1.7 g), and the dioxane was then removed under reduced pressure at a temperature below 40 ℃ under exclusion of moisture. The residue was treated with dry diethyl ether (100 mL), and the crystals of 2,5-oxazolidinedione were collected by filtration and dried over P2O5 in a vacuum desiccator. The crude product thus obtained, 16 g (89%), was recrystallized from ethyl acetate/petroleum ether to yield 14.3 g (77.2%) of pure material, which showed no melting point because of polymerization.
Into a suspension of finely ground glycine (15 g) in dry dioxane (750 mL), phosgene was introduced in a fine stream at 45–50 °C with efficient agitation. A clear solution was obtained after 5 h. This solution was filtered to remove unreacted glycine (1.7 g), and the dioxane was then removed under reduced pressure at a temperature below 40 °C with protection from moisture. The residue was treated with dry diethyl ether (100 mL), and the crystals of 2,5-oxazolidinedione were collected by filtration and dried over P2O5 in a vacuum desiccator. The crude product so obtained, 16 g (89%), was recrystallized from ethyl acetate/petroleum ether to yield 14.3 g (77.2%) of pure material, which showed no melting point because of polymerization.
