Patent ID: 8703986

Claim:
A process for preparing 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-C) compound, the process comprising steps of: reacting a liquid chlorinating agent and 9,10-dihydro-10-hydroxy-9-oxa 10-phosphaphenanthrene 10-oxide (DOPO-OH) compound represented by formula (B) to form a mixture, wherein the mixture comprises DOPO-C compound represented by formula (A) and an unreacted liquid chlorinating agent, separating the DOPO-C compound represented by formula (A) and the unreacted liquid chlorinating agent from the mixture to obtain the DOPO-C compound represented by formula (A); wherein the variables X 1 , X 2 , and X 3 are each independently selected from the group consisting of hydrogen atom, hydroxyl group, cyano group, sulfonic acid group, sulfonate ester group represented by —SO 3 R 1 , halogen atom, alkoxy group represented by —OR 2 , acyclic hydrocarbon group having 1 to 8 carbon atoms, cyclic alkyl group having 3 to 8 carbon atoms, aryl group, heteroaryl group, and arylalkyl group, wherein R 1 and R 2 are each independently an acyclic hydrocarbon group having 1 to 8 carbon atoms.