On account of the ease with which dicyandiamide can be prepared in quantity and at very small cost from the crude calcium cyanamide of commerce, this substance is beginning to find numerous applications in organic syntheses. Among other properties, the amidine structure of dicyandiamide has been taken advantage of for the preparation of certain nitrogen heterocycles. For example, by condensation with such substances as a-ketone acid esters, various pyrimidine derivatives are obtained. Thus, dicyandiamide condenses with amlonic ester derivatives and with acetoacetic ester to form substituted pyrimidines. It is not improbable that dicyandiamide is capable of entering into the same condensation reactions and yielding cyanamino derivatives or the various heterocycles now prepared from guanidine
