BigPatents India

A process for the preparation of a stabiliser mixture containing a low amount of chloride comprising a) 50 -80 % by weight of tetrakis(2,4-di-tert-butylphenyl)biphenylene diphosphonite and its isomers, b) 5 -25 % by weight of bis(2,4-di-tert-butylphenyl)biphenylene monophosphonite and its isomers, and c) 5 -25 % by weight of a tris(2,4-di-tert-butylphenyl) phosphite, and where the sum of components (a), (b) and (c) is not greater than 100 % by weight, by reacting biphenyl under Friedel-Crafts condition with phosphorus trichloride and aluminium trichloride and by reacting the product mixture with 2,4-di-tert-butyl-phenol in the presence of a tertiary amine or an aromatic amine and a solvent, separating the formed two layers, which process comprises treating the solvent layer with water, a base and a desiccant, separating the precipitate from the solution containing the stabiliser mixture and evaporating the sol- vent.