The reaction of nitrile with α-hydrogens under high pressure I : dimerization and trimerization of malononitrile

The effects of pressure on the reaction of malononitrile have been studied in water, methanol, ethanol, iso-propanol, dioxane, and so on in the temperature range of 323 to 343 K up to 8000 kg cm^-2. The reaction produced a dimer and two trimers only at high pressure. The dimer was identified as 1, 1, 3-tricyano-2-amino-1-propene and the trimers as 2, 4-diamino-3, 5-dicyano-6-cyanomethylpyridine, and ammonium 1, 1, 3, 3-tetracyano-2-cyanomethylpropenide, which are, respectively, the "Trimer 1" and "Trimer 2" reported by Schenck and Finken. The "Trimer 3" was not yielded.1. 3, 5-Tricyanomethyl-s-triazine was not produced in the present reaction either. The polar solvents and the addition of triethylamine increased the reaction rate remarkably. The formation of the dimer is autocatalytic and its mechanism is found to be a Thorpe-type reaction.