Phosphoryl chloride (11.0 mL, 120 mmol) was slowly added dropwise to anhydrous N,N-dimethylformamide (13.0 mL, 170 mmol) via a pressure-balanced addition funnel at 0 °C under stirring. After the dropwise addition, stirring was continued for 30 min. Subsequently, cyclohexanone (5.50 mL, 53.0 mmol) was added to the reaction system and the mixture was heated to reflux and maintained for 1 hour. After completion of the reaction, the system was cooled to 20 °C. At this temperature, a pre-formulated aniline/ethanol [1:1 (v/v), 180 mL] mixture was slowly added dropwise to the reaction mixture. After the dropwise addition was completed, the reaction was vigorously stirred at 20 °C for 30 min. The resulting dark purple reaction mixture was poured into a pre-cooled mixed solution of H2O/HCl [10:1 (v/v), 110 mL] and subsequently placed in an ice bath for 2 hours to crystallize. The crystals formed were collected by filtration, washed sequentially with cold water and ether, and finally dried under vacuum to afford the target product N-[(3-(anilinoiminomethylene)-2-chloro-1-cyclohexen-1-yl)methylene]aniline hydrochloride (14.8 g, 97% yield) as a dark purple solid. The product was characterized by 1H NMR (d6-DMSO, 250 MHz): δ 11.2 (s, 2H, NH), 8.55 (d, J = 14.0 Hz, 2H, CH olefin), 7.68 (d, J = 5.0 Hz, 4H, Ar-H), 7.44 (t, J = 7.0 Hz, 4H, Ar-H), 3.03 (t, J = 6.0 Hz. 4H, CH2-CH2), 2.05-1.98 (m, 2H, CH2-CH2).IR (ATR) spectrum showed characteristic absorption peaks located at 1609 (C=N), 1562, 1457, 1267, 1179, 752, 683, 565 cm-1.Mass spectrometry (ESI) analysis showed m/z: 323.22 [M+]. The melting point was determined to be 226-231 °C.
