Introduction. Quinazolines belong to the class of synthetic organic compounds exhibiting remarkably high pharmaceutical activity. Quinazoline and its derivatives are generally soluble in alcohols or organic solvents; however, this property limits their administration into the body. In contrast, the compounds formed with the chloride anion demonstrate solubility in water and isotonic solutions, which makes them suitable for parenteral (injectable) administration.

Experimental Section. 3-Ethylquinazolin-4(3H)-one was dissolved in acetone, and hydrogen chloride gas was passed through the solution, resulting in the formation of 3-ethylquinazolin-4(3H)-one hydrochloride. Rf = 0.67 (system: water : methanol, 1:1), melting point 175–177 °C.

Results and Discussion. The crystal belongs to the triclinic crystal system and crystallizes in the P-1 (No. 2) space group. The crystal lattice is of the primitive type. An inversion center is present in the structure, with the number of formula units per unit cell Z = 2. ADDSYM analysis revealed the presence of pseudotranslational symmetry (1/2, 0, 0).

In the compound, intermolecular N–H···Cl and C–H···Cl hydrogen bonds were identified. In addition, intramolecular N···C and C···Cl interactions were observed. Furthermore, Hirshfeld surface analysis and fingerprint plot analysis were performed, showing that the largest contribution arises from H···H/H···H contacts.

Conclusion. In this study, we reported the synthesis, structural characterization, and Hirshfeld surface analysis of a new quinazoline-based compound, (compound name). Based on the obtained results, the newly synthesized compound was found to exhibit confirmed biological activity.