A simple and efficient method has been developed for the synthesis of Quinazolines using SbCl₃ as a heterogeneous catalysis at room temperature. This method provides a good pathway for the synthesis of 2,3-Dihydroquinazolin-4(1H)-ones derivatives in the terms of excellent yields and short reaction times. Also we studied theoretically and experimentally on 2-phenyl-2,3-dihydroquinazolin-4(1H)-one (PDQ). Using density functional theory (DFT), the tautomerism of PDQ was also studied. Thermal stability of PDQ was studied by thermo gravimetric analysis (TGA). The spectroscopic results and theoretical calculations indicate that the strength of intramolecular hydrogen bonding (IHB) of PDQ is stronger than that in 2-methyl-4-quinolinol (2MQ). The absorption spectra of the PDQ in solvents with different polarity were obtained and the results show that PDQ exists in both keto-amine and enol-imine forms in THF, while it has keto-amine form in other solvents. Theoretical results show that the conductance of the two tautomers (keto-amine and enol-imine) varies greatly, which offers that the potential usage of this molecule is as a molecular device.