Novel synthesis of isotropic pitch from hydrocarbons and phosphorus pentasulfide

摘要

The phosphorus pentasulfide consists predominantly of a metastable rhombohedral crystal form. There are another metastableorthorhombic and a stable tetragonal forms. Although the conversion of the hexagonal metastable form into the other twoforms is immeasurably slow at room temperature, it is reasonably fast above 300 o C. The conversion must start with thebreaking of one of the covalent P-S bonds, which might result either in a reactive biradical or a reactive hybrid ion. Isotropicpitch was synthesized through the reaction between such reactive forms of phosphorus pentasulfide from pyrene above 300 o C.Pitch was produced at a very high yield of 85%. The resultant pitch consists of pyrene bond with phosphorus units.