Semicarbazide hydrochloride → 2-Chloro-5,6-dimethylnicotinaldehyde

Participants

Reaction Steps

A mixture of 2-chloro-3-cyano-5,6-dimethylpyridine (21.5 g), semicarbazide hydrochloride (24.0 g), sodium acetate (42.3 g), water (225 ml) and methanol (475 ml) was hydrogenated at 344 kPa at 50° using Raney nickel catalyst (5 g). The mixture was added to water (750 ml) and filtered. The solid filtered off was suspended in water (130 ml) and concentrated hydrochloric acid (70 ml) was added and the mixture was heated at 100° for 1 hour; formalin (40% w/w, 120 ml) was added and the mixture was heated at 100° for a further 0.5 hour and allowed to cool. Sodium acetate (95 g) and water (250 ml) were added and the mixture was extracted with ether and the extracts were washed with 5% aqueous potassium carbonate and evaporated to give 2-chloro-5,6-dimethyl-3-pyridinecarboxaldehyde (13.24 g, 60%), m.p. 69°-70°.

Provenance & Evidence