Pyridine → N-[(5-methylthiophen-2-yl)methylidene]hydroxylamine

Participants

Reaction Conditions

Reaction Steps

1.20 kg (9.51 moles) of 5-methyl-2-thiophenecarboxaldehyde and 727 g (10.46 moles) of NH2OH.HCl were placed in a reaction vessel and cooled to 10° C. Then, 0.85 L (10.46 moles) of pyridine was dropwise added thereto for 1 hour (an exothermic reaction: 10° C.→43° C). After 10 minutes, 7 L of benzene was added thereto and heated to remove the obtained water by Dean-Stark apparatus (initial internal temperature: 80° C.). After 165 mL of water was collected for 8 hours, (theoretical quantity: 171 mL), the product was cooled to obtain 5-methyl-2-thiophenecarboxaldehyde oxime. At this time, if stirring was stopped, two-phases were formed. After 0.85 L (10.46 moles) of pyridine was completely added at 15° C., 1.26 kg (12.36 moles) of Ac2O was dropwise added thereto for 25 minutes, with maintaining a temperature less than 15° C. The reaction mixture was stirred for 1 hour at room temperature, and completion of the acetylation reaction was confirmed by HPLC (2 phases).

Provenance & Evidence