The compound of the present application has a low melting point and excellent flexibility, and the like, so that a phthalonitrile resin or a prepolymer thereof or a polymerizable composition forming the same can exhibit excellent workability and a wide process window and it can be made to ensure improved impact strength. The compound can form the phthalonitrile resin or the like into a liquid phase or form it into a rubber phase. Such a phthalonitrile resin or the like can be applied to various applications.