Abstract: Fermenter for producing a shear-thinning medium comprising a tank volume and a stirring arrangement having an improved distribution capacity or a more uniform shear stress.

Abstract: The invention relates to a process for producing free-flowing dicarboxylic acid crystals from an aqueous solution or suspension of the dicarboxylic acid in a crystallizer.

Abstract: A process for preparing biphenols of the general formula I by reaction of monophenols of the general formula II where the radicals R1, R2 and R3 are each, independently of one another, hydrogen, alkyl, aryl or arylalkyl having from 1 to 10 carbon atoms, in the presence of an oxidant in a reactor, wherein a) the reactor comprises no stationary internals which act as baffles, b) a total of not more than 0.6 mol of oxidant is used per one mol of monophenol, and c) the oxidant is introduced either continuously or discontinuously in a plurality of portions over a period of from 10 minutes to 24 hours, with the amount of oxidant introduced per unit time not being constant over the total period of time but instead being varied.

Abstract: The present invention relates to a process for the preparation of polysulfones having a yellowness index according to DIN 6167 of less than 19 and polyether sulfones having a yellowness index according to DIN 6167 of less than 30, wherein the polymerization is carried out in basic, aprotic solvents with the use of a positively conveying stirrer passing close to the wall. The present invention also relates to the polyether sulfones and polysulfones obtainable for the first time by this process and to the use of such polymers for the production of moldings, films, membranes and foams.

Abstract: A process for preparing biphenols of the general formula I by reaction of monophenols of the general formula II where the radicals R1, R2 and R3 are each, independently of one another, hydrogen, alkyl, aryl or arylalkyl having from 1 to 10 carbon atoms, in the presence of an oxidant in a reactor, wherein a) the reactor comprises no stationary internals which act as baffles, b) a total of not more than 0.6 mol of oxidant is used per one mol of monophenol, and c) the oxidant is introduced either continuously or discontinuously in a plurality of portions over a period of from 10 minutes to 24 hours, with the amount of oxidant introduced per unit time not being constant over the total period of time but instead being varied.