Benzaldehyde → beta-(1-Ethyl-5-nitro-2-imidazolyl)styrene

Participants

Reaction Steps

A slurry of β-(1-ethyl-5-nitro-2-imidazolyl)styrene (42.7 g. or 0.175 mole) in 350 ml. of methanol containing 14.6 ml. of water at 25° C. is treated with ozone until a nearly clear, pale-yellow solution is obtained. Subsequently, the mixture is treated with 42 g. of sodium iodide in 138 ml. of water and 20.3 ml. of glacial acetic acid at 25° C. The mixture is stirred for 40 minutes and 44.1 g. (0.288 mole) of sodium thiosulfate in 242 ml. of water added. The mixture is filtered, and the filtrate concentrated at 70°-75° C. under 15-20 mm. of pressure to give 450 ml. of solution. The solution is acidified with 50 ml. of 6N hydrochloric acid and the benzaldehyde removed at 70°-75° C. under 15-20 mm. of pressure. The residue is then neutralized with saturated sodium bicarbonate solution and extracted with ethyl acetate to give an 81.5% yield of solid aldehyde, melting point 61°-67° C. after stripping. A sublimed sample of the aldehyde melts at 68°-69° C. with softening at 65° C. When the aqueous ozonized solution, after benzaldehyde is removed, is treated with thiosemicarbazide and mineral acid or semicarbazide hydrochloride and heated, the 1-ethyl-5-nitro-2-imidazolecarboxaldehyde thiosemicarbazone, melting points 241° C., or semicarbazone, melting point 223°-226° C., is obtained. The compound β-(1-ethyl-5-nitro-2-imidazolyl)styrene is prepared by treating 1-ethyl-2-methyl-5nitroimidazole with benzaldehyde in absolute ethanol and potassium tertiary butoxide in nitrogen atmosphere below 37° C. A sample purified from 95% ethanol melts at 136.5°-137.5° C.

Provenance & Evidence