Nano-CoCr₂O₄ Catalysts Promote the Synthesis of Diamino Pyrimidine Oxide Derivatives

Abstract— 2,6-Diamino-4-N(R¹R²)-pyrimidine N-oxide, as a heterocyclic drug, has the functions of lowering blood pressure and treating Parkinson's disease. At the same time, androgenetic alopecia syndrome can also be treated by topical stimulation of hair growth and baldness recovery, as well as by increasing prostaglandin endoperoxide. In this experiment, spinel chromite nanocatalysts (MCr₂O₄, M = Co, Ni, Mg, Cu, Ca, and Zn) were prepared by sol-gel method. Also, nano-CoCr₂O₄ catalysts were characterized using thermo gravimetric analyzer, dynamic stability control, X-ray diffraction, search engine marketing, transmission electron microscope, and Fourier transform infrared techniques. The homemade spinel chromite was utilized as efficient and green heterogeneous catalysts for N-oxidation of 2,6-diamino-4-chloropyrimidine with H₂O₂ in ethanol solution at 50°C to obtain the intermediate 2,6-diamino-4-chloropyrimidine N-oxide. A series of 4-substituted diaminopyrimidine oxides were finally obtained. Among different spinel chromites, CoCr₂O₄ exhibits remarkable catalytic activity with a yield of 95.6% within 90 min. In addition, CoCr₂O₄ was continuously recycled for 5 times without significant decrease in catalytic activity.