Cyano-modified active ester as well as preparation method and application thereof

The invention provides cyano-modified active ester as well as a preparation method and application thereof. The active ester is prepared from the following raw materials: a multifunctional phenolic compound with a structure as shown in a formula I, a monofunctional acyl halide compound and cyanogen halide. The active ester is prepared from three specific raw materials, the molecular structure of the active ester contains an active ester group and a cyano group, and the two active groups cooperate with each other, so that the active ester is endowed with low dielectric loss, low dielectric constant, low water absorption and high reaction crosslinking sites. The epoxy resin composition taking the active ester as the curing agent has excellent dielectric property, heat resistance, humidity and heat resistance and low thermal expansion coefficient after being cured, so that the resin composition can fully meet the performance requirements of a high-performance circuit substrate. 本发明提供一种氰基改性的活性酯及其制备方法和应用，所述活性酯的制备原