Background: One of the principal factors in the field of research in green chemistry is
to drive chemical reactions using ultrasonication as a versatile synthetic tool. Moreover,
nanostructured metal salts occupy an important position as low cost, efficient, heterogeneous, and
green catalysts in chemical reactions. Pyrimidine has also acquired significance because it is a core
structure in a variety of natural and non-natural agents, many of which display versatile biological
activities and medical applications.
Objective: The aim of this study was to explore the role of nickel(II) chromite nanoparticles
(NiCr2O4 NPs) as a green and recyclable catalyst for the synthesis of 2,4-diamino-6-arylpyrimidine-
5-yl cyanides under ultrasonic radiation.
Methods: A direct cyclocondensation reaction of guanidine nitrate, aromatic aldehydes, and
malononitrile was performed using NiCr2O4 NPs as an effective heterogeneous catalyst under
ultrasonic radiation at room temperature conditions to prepare 2,4-diamino-6-aryl-pyrimidine-5-yl
cyanides in high yields. The described catalyst was prepared successfully according to a simple
hydrothermal route and fully characterized by the X-Ray diffraction (XRD) technique, dispersive
energy X-Ray (EDS) analysis, scanning electron microscopy (SEM), and dynamic light scattering
Results: A number of 2,4-diamino-6-aryl-pyrimidine-5-yl cyanides were effectively synthesized in
high yields (94-98%) within short reaction times (15 min). All synthesized compounds were well
characterized by IR, 1H and 13C NMR spectroscopy, and also by elemental analyses.
Conclusion: In conclusion, a simple, efficient, and green synthesis of 2,4-diamino-6-arylpyrimidine-
5-yl cyanides was developed using NiCr2O4 NPs as a green nanocatalyst, and under
ultrasound radiation as a green tool. The mild reaction conditions, avoiding the use of toxic
solvents or reagents, high atom economy, high yields, and simple workup are the attractive
features of this new protocol.