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20th March 2018 @ 14:20

Method:

2-chloro-6-(2-hydrazinyl(4-nitrobenzylidene))pyrazine) (106 mg, 0.34 mmol, 1.0 equiv.) was dissolved in DCM (20 mL) forming a yellow solution. PIDA (109 mg, 0.34 mmol, 1.0 equiv.) was then added. The reaction was stirred for 2 hours at room temperature before heating to 30 °C for a further hour, yielding a yellow solution with a small amount of precipitation. The reaction was monitored by TLC (Ethyl acetate) showing that only a small amount of starting material remained. The reaction was quenched with saturated sodium hydrogen carbonate solution. The organic layer was isolated by separation with brine before drying over MgSO4. The dried filtrate was concentrated in vacuo to a dark yellow solid. The crude product was characterised by IR and 1HNMR before purification by silica column with ethyl acetate, followed by 5% MeOH in DCM as the solvent system. A bright yellow powder (34 mg, 35.7 %) was obtained and the pure product, 5-chloro-3-(4-nitrophenyl)-[1,2,4]triazolo[4,3-a]pyrazine, was then characterised by IR, 1H NMR, and 13C NMR , DEPT, 1H-13C HSQC and MS.


Attached Files
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1H NMR pure 5-chloro-3-(4-nitrophenyl)-[1,2,4]triazolo[4,3-a]pyrazine unzoomed.pdf
1H NMR pure 5-chloro-3-(4-nitrophenyl)-[1,2,4]triazolo[4,3-a]pyrazine zoomed.pdf