Synthesis of (4-chlorobenzylidene)-(2-chloropyridi-3-yl)amine

Schiff bases are widely in use for synthetic purposes both by organic and inorganic chemists.¹ They are used as biological, analytical, polymer and liquid crystalline materials.² Schiff bases are reported to show a variety of biological activities such as antibacterial^3,4,5, antifungal^6,7, anticancer ^8,9 and herbicidal ¹⁰ activities . Pyridinium compounds have biological activities¹¹ such as antifungal¹² and antibacterial^12,13 activities. The presence of a chloro moiety in different types of compounds causes them to exhibit pesticidal activity.¹⁰

A mixture of 3-amino-2-chloro pyridine 1 (1.28 g, 10 mmol), 4-chlorobenzaldehyde 2 (1.40 g, 10 mmol) and anhydrous sodium sulfate (4.00 g) in dry dichloromethane (40.00 mL) was stirred at room temperature for seven hours. The suspension was filtered and washed with dichloromethane. The solvent was evaporated and new schiff base 3 was formed, which was washed with 10 mL acetic acid 5%, 10 mL NaHCO₃ 5% and water, successively, (2.04 g, 82 %).

Melting point: 54-56^oC.

IR(KBr, cm^-1): 1600.1 (CH=N); 1624.0 (C=N pyridine ring).

¹H-NMR (250MHz, CDCl₃): δ= 6.97-8.17 (7H, m, 2 Ph); 8.31 (1H, s, HC=N).

¹³C-NMR (62.9 MHz, CDCl₃): δ= 123.55-146.49 (aromatic carbons); 162.55 (HC=N).

MS (m/z, %): 251 ([M⁺], 63.3); 250 (M-1, 100.0); 215 (C₅H₃NClN=CC₆H_{4 ,} 14.8); 139 (C₅H₃NClN=C, 15.4); 112 (C₅H₃NCl, 52.2 ), 89 (C₅H₃NN, 19.4); 77 (C₅H₃N, 15.1).