Hydrochloric Acid → 4-Amino-6-methyl-2,5-dihydro-1,2,4-triazin-3-one

Participants

Reaction Conditions

Reaction Steps

A suspension is prepared of 6-methyl-4-acetylamino-4,5-dihydro-1,2,4-triazin-3-(2H)-one in methanol. The suspension is heated to 45° C. and becomes a clear colourless solution. At between 45° C. and 50° C. gaseous HCl (a) or aqueous HCl (b) is added to this solution over a 2 to 3 hour period. After about 30% of the gaseous HCl (a) or 50% of the aqueous HCl (b) has been added the reaction mixture is seeded with 4-amino-6-methyl-3-oxo-2,3,4,5-tetrahydro-1,2,4-triazine hydrochloride. Thereafter 4-amino-6-methyl-3-oxo-2,3,4,5-tetrahydro-1,2,4-triazine precipitates out continuously as the hydrochloride salt. After about 2 hours stirring, the maximum conversion is reached. The reaction mixture is brought to pH 5 by the addition of 50% NaOH solution, thereby forming free 4-amino-6-methyl-3-oxo-2,3,4,5-tetrahydro-1,2,4-triazine.

Provenance & Evidence