Doxofylline Impurity 2 Catalogue D349272 CAS 7029-96-1 M.W 266.26 M.F C11H14N4O4 Specifications FAQs ethyl 2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)acetate