Guanidine, reaction with acetylacetone

Condensation reactions of aniline and of other bases with aromatic aldehydes to give Schiff s bases are accelerated by ultraviolet light in buffered media. For example, o-phenylenediamine reacts with formic acid to yield benzimidazole and acetylacetone reacts with guanidine to form 2-amino-4,6-dimethylpyrimidine.162 Similarly, lobelanine is formed by the photocondensation of glutaraldehyde, benzoylacetic acid, and methylamine hydrochloride.163... 

The reactivity of the amino group can be strongly influenced by the presence of negative substituents in the amine molecule. For example, trinitroaniline and trichloroaniline do not react. On the other hand, in addition to primary aliphatic amines, aromatic amines, and amino acids, substances with an active methylene group also react (3). A positive reaction was also observed with substances such as guanidine, semicarbazide, phenyl-hydrazine, ethyleneimine, piperidine, piperazine, benzylcyanide, cyano-acetylacetone, diethyl malonate, ethyl acetoacetate, dibenzoylmethane, rhodanin, indole, methylphenylpyrazolone, resorcinol, phloroglucinol, and quaternary heterocyclic bases and oxonium salts. 

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