1,3,4-Oxadiazole

Description1,3,4-Oxadiazole is a five-membered, conjugated, planar, stable heteroaromatic, comprised of two adjacent nitrogen atoms at the 3,4-positions with one oxygen atom and two vicinal carbon atoms. Each nitrogen atom in the ring is one carbon apart from the oxygen heteroatom. The 1,3,4-oxadiazole ring is electron deficient due to the presence of two pyridine-like nitrogen atoms in the ring and as a result its chemical properties are unlike those of furan as evidenced from the downfield chemical shift of C2(5)H at δ 8.73 ppm (CDCl3) of the parent 1,3,4-oxadiazole. The presence of two electronegative nitrogen atoms deactivates the ring, making electrophilic substitution difficult in the ring at the C2- and C5-positions. From a medicinal chemistry point of view, it is a very important molecule because it is a surrogate of carboxylic acids, esters, and carboxamides and displays a wide spectrum of pharmacological activities.

Uses1,3,4-Oxadiazole has therapeutic potential with antibacterial, anti-mycobacterial, antitumor, anti-viral and antioxidant activity.

PreparationA solution of potassium hydroxide (4 pellets) was made in absolute ethanol (40ml) & poured into a round bottom flask. 10g of prepared hydrazide and 10ml of carbon disulphide was added in the round bottom flask. Condenser was adjusted and allowed to reflux for 6-8 hours. Reaction progress was checked at regular intervals by using TLC procedure with the use of varying ratio of n-hexane & ethyl acetate. As the reaction got completed, 20ml of chilled distilled water and a very small amount of dil. Sulfuric acid (H2SO4) to maintain the pH 2-3 in order to remove un-reacted base. Solid precipitates were obtained on vigorous shaking and filtered. Product was dried, collected &calculated.