Hydrochloric Acid → 3-(4-Methoxyphenyl)pyrazin-2(1H)-one

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Reaction Steps

p-Methoxyphenyl glycinamide (0.10 mole) in 125 ml. methanol cooled to -30° C. is treated with a solution of 19.3 g. (0.10 ml.) of 30% glyoxal in 25 ml. methanol also precooled to -30° C. The mixture is stirred and added dropwise during 15-30 minutes to 10 ml. (0.125 mole) of 12.5 N aqueous sodium hydroxide, the temperature of the reaction mixture being held at -20° to 15° C. during this addition. The mixture is refrigerated 1-2 hours at -10° C., then 1 hour at -2° to 3° C., whereupon there is added 12 N HCl followed by 5 g. solid sodium bicarbonate to neutralize any excess acid. The solution then is evaporated to dryness and the residue extracted with chloroform. The extracts are evaporated and the product crystallized from a suitable solvent mixture, i.e. chloroform-methanol to give 2-hydroxy-3-p-methoxyphenylpyrazine.

Provenance & Evidence