Patent ID: 7754924
Filing Date: 2010-07-13
Classification: C07F

Abstract:
1. A process of preparing an aromatic phosphine monosulfonate in zwitterionic form, the process comprising: (a) contacting an aromatic phosphine with a sulfonating agent under reaction conditions sufficient to obtain a product mixture comprising an acid form of an aromatic phosphine monosulfonate, in which the sulfonate group and phosphorus atom are both protonated, and unconverted sulfonating agent; (b) quenching or removing substantially all of the unconverted sulfonating agent; (c) partially neutralizing the acid form of the aromatic phosphine monsulfonate with an aqueous solution of a neutralizing agent (first neutralizing agent) to an endpoint at a pH between 2.0 and 5.0 under conditions sufficient to phase separate substantially all of the aromatic phosphine monosulfonate in zwitterionic form, namely the aromatic phosphine monosulfonate in which the sulfonate group is deprotonated and the phosphorus atom is protonated; and (d) collecting the zwitterionic form of the aromatic phosphine monosulfonate as a solid or neat liquid.