Abstract: A process for the preparation of a stabilizer 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 stabilizer mixture and evaporating the solvent.

Abstract: Molecular complex compounds comprising a mono-, bis- or trisacylphosphine oxide compound with an .alpha.-hydroxy ketone compound are suitable as photoinitiators for the photopolymerization of free-radically polymerizable compounds.

Abstract: Described are compositions comprising (a) 25 to 99% of organic phosphite or phosphonite, based on the total weight of the composition, (b) an effective stabilizing amount of organic amine, and (c) an effective stabilizing amount of acid-binding metal salt, wherein said composition comprises no organic polymers or alkali metal phosphates as further components, as well as a process for stabilising organic phosphites or phosphonites against hydrolysis by addition of organic amine and acid-binding metal salt. The compositions are distinguished by their excellent stability to hydrolysis and have good storage stability even at high atmospheric humidity. The novel compositions and process products can be used with advantage as stabilisers for organic material against the harmful action of heat, oxygen and/or light.

Abstract: The substituent X in the phenols of the formula: ##STR1## wherein R.sub.1 to R.sub.4 are hydrogen or unsubstituted or substituted alkyl, alkenyl or alkynyl, and X is secondary or tertiary alkyl of 3 to 9 carbon atoms, can be removed by heating said phenols in the presence of an alkali metal hydrogensulfate.