Commercial Organophosphorus Chemicals: Status and New Developments

By definition, organophosphorus chemicals are those with at least one P-C-bond. They all are downstream-products of elemental phosphorus – mostly of the P4-allotrope – though with very few exceptions they cannot be synthesized directly from phosphorus element; instead, use has to be made of P4-derivatives, such as PCl3, PH3 or sodium hypophosphite (SHP). By the end of the 90th and the early 2000 novel processes for the production of organophosphorus chemicals and their transformation, resp., were developed and partly commercialized. Examples are olefin addition reactions to SHP, leading to novel flame retardants (EXOLIT® OP-types, Clariant), or to a new way of making a well-known extraction agent for the separation of Cobalt and Nickel (IONQUEST® 290, Rhodia, now Solvay). Various methods to produce organophosphorus chemicals in commercial scale are described. Using the example of methylphosphonous acid, existing and new routes are shown to synthesize that key intermediate for herbicide BASTA® (Bayer) and flame retardants like EXOLIT® OP (Clariant).