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20th March 2018 @ 14:16

2-chloro-6-(2-hydrazinyl(4-chlorobenzylidene))pyrazine) (88 mg, 0.33 mmol, 1.00 equiv.) was dissolved in DCM (20 mL) forming a pale yellow solution. PIDA (114 mg, 0.35 mmol, 1.1 equiv.) was then added. The pale yellow solution became progressively darker over two hours. The reaction was stirred for 2.5 hours at room temperature before heating to 30 °C. The reaction was monitored by TLC (7:3 Ethyl acetate: PET ether) however starting material remained so it was left stirring at room temperature overnight. After 22.5 hours the solution was a darker yellow- orange and TLC showed 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 white powder. The crude product was characterised by IR and 1H NMR before purification by silica column (15 g silica) with initially a 1:1 Ethyl acetate: PET ether solvent system then 7:3 Ethyl acetate: PET ether after the starting material had eluted. A cream powder (81 mg, 93 %) was obtained and the pure product, 5-chloro-3-(4-chlorophenyl)-[1,2,4]triazolo[4,3-a]pyrazine, was then characterised by IR, 1H NMR, and 13C NMR , DEPT and MS.

Attached Files
1HNMR Spectrum of 5-chloro-3-(4-chlorophenyl)-[1,2,4]triazolo[4,3-a]pyrazine.pdf