Diaminouracil hydrochloride

The crude product is readily purified by conversion to its hydrochloride salt. The bisulfite salt is transferred to a wide-mouthed 1-1. flask, and concentrated hydrochloric acid is added until the consistency of the resulting mixture is such as to permit mechanical stirring (100 to 200 ml. of acid). The slurry is heated on a steam bath with stirring for 1 hour Hood ). The tan diaminouracil hydrochloride is filtered on a sintered glass funnel, washed well with acetone, and vacuum-dried over phosphorus pentoxide. The yield of diaminouracil hydrochloride is 104-124 g. (68-81%) (Notes 6 and 7). 

If placed in a preheated melting-point block, the product melts with decomposition in the range 300-305°. Diaminouracil hydrochloride in 0.1 N hydrochloric acid has a well-defined absorption peak at 260 mju, log e = 4.24. Satisfactory analyses for nitrogen and chlorine are difficult to obtain with this type of compound although good results are obtained for carbon and hydrogen. 

Diaminouracil bisulfite, 37, 16 Diaminouracil hydrochloride, 37,15 Diamylamine, 32, 2 Di-n-amyl ketone, 31, 71... 

A related reaction is the alkoxide-catalyzed condensation of urea with ethyl cyanoacetate as the first step in a synthesis of 5,6-diaminouracil hydrochloride (Taylor "). Since the overall yield was high, the yield in the critical condensation... 

The procedure for the formation of diaminouracil bisulfite is slightly modified from that of Cain, Mallette, and Taylor,2 which in turn is derived from preparations of Bogert and Davidson,8 and Traube.4 The sulfate salt may be formed in lower yield than the hydrochloride described here by dissolving the bisulfite salt in aqueous base and precipitating with sulfuric acid.8-4 The hydrochloride is appreciably soluble in water, while the sulfate salt is only slightly soluble. 

---