Hydrochloric Acid → 1-methyl-1,3,5-triazine-2,4(1h,3h)-dione

Participants

Reaction Conditions

Reaction Steps

A reaction mixture consisting of 70.2 gm. (0.6 mole) of the 1-methylbiuret prepared in Part A above, 3.5 liter absolute ethanol, and 200 ml. benzene is heated to the reflux temperature with stirring in a 5-liter, three-necked flask fitted with a reflux condenser, a stirrer, and thermometer. The top of the condenser is fitted with a nitrogen outlet, but no water is run through the condenser. After removing the nitrogen outlet, 200 ml. of the medium is allowed to distill through the condenser. The reaction mixture is then cooled to 60° C., before 28 gm. (1.2 mole) of sodium metal is added slowly over an interval of five (5) minutes. A white solid precipitates, but stirring is continued until all the sodium is dissolved. At this point, 104 gm. (1.4 mole) of ethyl formate is added in one portion and the reaction mixture is again heated to the reflux temperature (about 75° C.) and refluxed for three (3) hours. The reaction mixture is cooled to about 30° C. and hydrogen chloride gas is blown over the surface until an acid pH is attained. The reaction mixture is again heated at the reflux temperature for 15 minutes. The hot mixture is filtered through a diatomaceous earth filter and the filter is washed with hot ethanol. The filtrate and washings are concentrated to a volume of 200 to 300 ml. by removing medium by evaporation under reduced pressure. The concentrate is cooled to 5° C. and set aside at that temperature for several hours for crystallization. The crystals are collected on a filter and washed with cold ethanol. After drying the crystals under reduced pressure there is obtained 69 gm. (90% yield) of 1-methyl-5-azauracil having a melting range from 200° C. to 205° C. A sample recrystallized three times from ethanol has a melting point of 213° C. to 214° C.

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