Process for stabilizing organophosphorus compounds
AssigneeEthyl Corporation
InventorsRichard D. Glass, Vincent J. Gatto
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Abstract
Organophosphorus compounds are stabilized against decomposition during and after recovery from their synthesis reaction mixtures by the addition to the synthesis reaction mixture of at least 0.5% by weight of an acid scavenger, based on the weight of the organophosphorus compound, before allowing the organophosphorus compound to crystallize. The invention is of particular value in the stabilization of 2,2'-alkylidenebis(dialkylphenyl)fluorophosphonites, such as 2,2'-ethylidenebis(4,6-di-t-butylphenyl)fluorophosphite, which is rendered more suitable for use as a stabilizer for organic polymers, e.g., polycarbonates, by the practice of the invention.
Claims19
In a process for recovering an organophosphorus compound from its synthesis reaction mixture, the improvement which comprises minimizing or preventing its decomposition by adding to the synthesis reaction mixture at least 0.5% by weight of an acid scavenger, based on the weight of the organophosphorus compound, before allowing the organophosphorus compound to crystallize.
In a process for recovering from its synthesis reaction mixture a 2,2'-alkylidenebis(dialkylphenyl)fluorophosphite which has been prepared in a halohydrocarbon solvent by (1) refluxing the reaction mixture to remove a portion of the halohydrocarbon solvent, (2) adding a crystallization solvent selected from heptane, water, acetonitrile, and alcohols to the refluxing mixture while continuing to remove halohydrocarbon solvent to replace it with the crystallization solvent and permit crystallization of the 2,2'-alkylidenebis(dialkylphenyl)fluorophosphite, (3) adding supplemental crystallization solvent, (4) after refluxing the resulting slurry, cooling it to precipitate the solids, and (5) isolating the precipitated solids by filtration, the improvement which comprises minimizing or preventing decomposition of the 2,2'-alkylidenebis(dialkylphenyl)fluorophosphonite by adding to the synthesis reaction mixture at least 0.5%, based on the weight of the 2,2'-alkylidenebis(dialkylphenyl)fluorophosphite, an acid scavenger selected from metal carboxylates, oxides, and carbonates prior to exchanging the crystallization solvent for the halohydrocarbon solvent.
Dependencies are inferred from the claim text.