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22nd March 2018 @ 14:45


2-chloro-6-hydrazinopyrazine (202.0 mg, 1.39 mmol, 1.00 equiv.) was partially dissolved in EtOAc (30 mL) forming a yellow solution before addition of 2-hydroxybenzaldehyde (0.2 mL, 1.92 mmol, 1.2 equiv.). The reaction was heated under reflux under a Dean-Stark trap for 1 hour, darkening the solution slightly, however no water was collected in the trap. After 1 hour at reflux, a TLC of the reaction mixture revealed that the reaction had reached completion. The solvent was removed in vacuo giving an orange powder which was shown to contain 2-hydroxybenzaldehyde, desired product, and an unknown side product. The powder was recrystallized from boiling ethanol to give yellow needle like crystals (123 mg). The crystals were analysed by NMR and IR spectroscopy and mass spectrometry to determine that they were salicylaldehyde azine formed by a side reaction with free hydrazine impurities in the 2-chloro-6-hydrazinopyrazine. The filtrate was therefore collected and concentrated in vacuo giving an orange powder (209 mg) analysed by NMR and IR spectroscopy to contain 2-chloro-6-(2-hydrazinyl(2-hydroxybenzylidene))pyrazine and salicylaldehyde azine in a 2:1 molar ratio.

Attached Files
2-chloro-6-(2-hydrazinyl(2-hydroxybenzylidene))pyrazine) 1H.pdf