Abstract: The organic substance present in the form of a melt is cooled below its solidification point in a twin-screw extruder so that it crystallizes out. The crystallized material is then extruded through a breaker plate at the end of the screw extruder and further cooled. It is essential that the temperature prevailing in the screw extruder, its rotational speed and the temperature of the breaker plate should be adjusted such that from 70% to 99.5% and preferably from 95 to 99.5% of the material has solidified by the time it reaches the end of the screw, the non-crystallized liquid residue only crystallizing out during the subsequent cooling operation. Accordingly, a small residue of melt is present during extrusion through the breaker plate. In addition, extrusion is facilitated if the breaker plate is kept at a temperature in the vicinity of the melting point of the material in question.

Abstract: Complexes of nickel or cobalt with phosphine, phosphite, stilbene or arsine ligands, especially nickel-phosphine complexes, useful as catalysts.

Abstract: A process for the polymerization of aromatic vinyl compounds and their copolymerization with alkyl esters or nitriles of acrylic and/or methacrylic acid, wherein1. in a first stage, the monomer or monomers is or are continuously introduced at excess pressure into a first reaction zone and polymerized there to a degree of conversion of 5 - 40% by weight at a temperature of from 80.degree. to 170.degree. C;2. in a second stage, the reaction mixture is conducted at constant pressure into a second reaction zone designed for conducting highly viscous melts, the mixture flowing through this reaction zone at a rate which is 1.1 to 5 times the intrinsic rate, and polymerized there to a degree of conversion of 40 to 95% at temperatures of from 120.degree. to 250.degree. C, the excess pressure in the first and second stage being chosen so that the monomer or monomers is or are liquid, and the polymer is continuously removed from this zone with release of the pressure; and3.

Abstract: Carbonyl-free complexes of nickel or cobalt with an olefinic compound which are useful as catalysts.