Nitration of barbituric acid at 40 degrees C gave the previously unknown 5,
5-dinitrobarbituric acid (3), which readily underwent hydrolysis to dinitro
acetylurea (5), which in turn could be hydrolysed in basic media to the pot
assium salt of dinitromethane. Alloxane was prepared in a one step procedur
e by thermal decomposition of 5,5-dinitrobarbituric acid in hot acetic acid
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