THE EFFECT OF PRESSURE ON THE TRIMERIZATION AND DIELS-ALDER REACTION OF CYANOACETYLENE - SYNTHESIS AND REACTIVITY OF 2,3,5-TRICYANOBICYCLO[2.2.0]HEXA-2,5-DIENE (TRICYANO DEWAR BENZENE)

The trimerization of cyanoacetylene (1a) and the Diels-Alder reaction of 1a with 1,3-cyclohexadiene (2) show a powerful pressure-induced acc eleration which allows the reaction temperature to be reduced from 160 degrees C at 1 bar to 40 degrees C at 12 kbar or from 100 degrees C a t 1 bar to room temperature at 7 kbar. At high pressure thermally unst able intermediates like the tricyano Dewar benzene 12 generated in the trimerization of 1a or the primary adduct 3a formed in the Diels-Alde r reaction of 1a with 2 were isolated.