Process for the preparation of 6-oxo-(6H)-dibenz-(c,e)(1,2)-oxaphosphorines (ODOP)

摘要

Prodn. of 6-chloro-6H-dibenz(c,e)(1,2)oxa-phosphorines of formula (I) comprises reacting o-phenyl-phenols of formula (II) with PCl3 in the presence of a Lewis acid at 70-220 deg.C, provided that the molar ratio of unreacted PCl3 to (II) in the reaction mixt. is maintained at at least 0.05:1 throughout the reaction time: R1-R6 = H, halogen, 1-4C alkyl or 1-4C alkoxy.