Bayer Aktiengesellschaft

Joachim Maas

Hans-Heinrich Moretto

Helmut Steinberger

Bruno Degen

Hans L Kuhnlein

Karl-Heinz Schultz

Gunther Maass

Klaus Seyfried

Hans R Kung

Rudolf Mundil

Jurgen Groening

Hansruedi Forter

Hans-Joachim Lucking

Anti-foam formulation containing an organopolysiloxane

The invention procides a circulation evaporator for concentrating mineral acid, particularly sulphuric acid, comprising parts of, or at least coated with, enamel, characterized by a heat exchanger for heating the acid comprising at least one acid feed pipe provided with an enamel layer, means being provided to maintain the compressive stress in the enamel layer under all working conditions, said acid feed pipe being connected at its inlet end to a circulation pump and at its outlet end to a flash evaporator for concentrating the heated acid, this evaporator being connected by a circulation pipe to the pump inlet and to means for introducing the crude acid, for discharging the concentrate and for carrying away the vapors.

Evaporator for concentrating mineral acid, particularly sulphuric acid

In the preparation of catalytic copper with an average particle size between about 0.1 and 100 microns and a copper-I oxide content of about 3 to 100% by oxidation of a Cu powder, the improvement which comprises carrying out the oxidation with oxygen at a reduced partial pressure compared with that of air, the resulting catalyst being of enhanced catalytic activity especially for the reaction of hydrocarbon chlorides with silicon for the production of organochlorosilanes (Rochow synthesis) wherein the desired material is produced in higher yield and greater selectivity.

Preparation of catalytic copper and production of organochlorosilane

In the preparation of a cyclic diphenylsiloxane of the formula ##STR1## WHEREIN N IS 3 OR 4, BY HYDROLYSIS OF A DIPHENYLDIHALOGENOSILANE, THE IMPROVEMENT WHICH COMPRISES ADDING THE DIPHENYLDIHALOGENOSILANE, IN THE PRESENCE OF AN ORGANIC, APROTIC SOLVENT TO AN AQUEOUS BASIC SOLUTION, THE BASE BEING EMPLOYED IN AN AMOUNT WHICH IS AT LEAST STOICHIOMETRICALLY EQUIVALENT TO THE HALOGEN CONTENT, WHEREBY THE CYCLIC DIPHENYLSILOXANE IS OBTAINED IN HIGH YIELD AND PURITY. The base is preferably lithium hydroxide, potassium hydroxide or sodium hydroxide and is used in the form of an at least 5 molar solution, about 2.1 to 2.5 equivalents being used per mole of diphenyldihalogenosilane.

Preparation of cyclic diphenylsiloxanes

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Bergheim, Germany

Joachim Maas