Pyrazine‐Activated Cyano‐allyl Reaction Chemistry for Molecular‐Engineered High Performance Thermoset

Pyrazine dicarbonitriles functionalized with allyl groups (APQ and BAPPQ) were synthesized to address the high melting point and low curing reactivity of conventional phthalonitrile (PN) resins. APQ exhibits significantly reduced melting temperatures (as low as 50.9 °C) and curing initiation temperatures (around 150°C), along with wide processing windows (up to 150°C). Remarkably, an "Ene" reaction between cyano and allyl groups was identified, leading to imine formation in the early stage of curing below 200°C. Meanwhile, the traditional cyano polymerization mechanism also operates under elevated curing temperature, generating azaisoindoline, azaphthalocyanine, and triazine structures. The resin cured at 275°C shows high thermal stability (T_g = 346.8°C, char yield = 75.8%), and superior flame-retardance performance (HRC = 18.1 J g^-1 K^-1, THR = 1.6 kJ g^-1). This work offers a new strategy for designing processable and high-performance aromatic nitrile resins.