2,4,5,6(1H,3H)-pyrimidinetetrone 50-71-5 InChI=1/C4H2N2O4/c7-1-2(8)5-4(10)6-3(1)9/h(H2,5,6,8,9,10 pyrimidine-2,4,5,6(1H,3H)-tetrone