Abstract: An apparatus and a process for crystallizing substances from solutions or dispersions containing these substances, in a crystallizer containing a classifying zone (3), comprise a) an inner and an outer circulation system (1; 2), the inner circulation system (1) being present in the crystallizer, the inlet of the outer circulation system (2) being connected to the inner circulation system (1) via the classifying zone (3), the outer circulation system, being present outside the crystallizer, the outlet of the outer circulation system (2) being connected to the inner circulation system (1) of the crystallizer, and a means for dissolving crystals being arranged in the outer circulation system (2), before its outlet, b) an inflow (4) for solution and/or dispersion, which inflow is present on the crystallizer or on the outer circulation system, and c) an outflow (5) for dispersions, which outflow is arranged on the crystallizer or on the outer circulation system.

Abstract: A system comprising

Abstract: A process for preparing 1,2-dichloroethane by reacting about 2 mols of ethylene, about 4 mols of hydrogen chloride and about 1 mol of oxygen in the presence of a fixed bed of supported catalyst based on copper(II) chloride in only one reaction zone at a pressure of from 2 to 10 bar and at from 220 to 280° C.

Abstract: An apparatus and a process for crystallizing substances from solutions or dispersions containing these substances, in a crystallizer containing a classifying zone (3), comprise

Abstract: A process for producing solids by precipitation in a mixer to form a mixture of solid and liquid, where the starting materials are fed into a mixing apparatus which has essentially a rotationally symmetrical mixing chamber which has a rotor disposed therein and is formed by a peripheral wall and two end walls, and where a) the starting materials are each fed to at least one inlet opening in the peripheral wall of the mixing chamber, and b) the solid-containing mixture which is formed is removed from at least one outlet opening in the peripheral wall of the mixing chamber.

Abstract: Compounds of the formula I and II ##STR1## where R.sup.1 is hydrogen or an aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radical or an acyl radical, it being possible for these radicals to carry further substituents which do not react with acetylenes or allenes, and the radicals R, independently of one another, are hydrogen or aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radicals which may be linked to one another with formation of a ring and m is 0 or 1, are prepared by an addition reaction of a compound of the formula IIIR.sup.1 OH IIIwith an acetylene or allene of the formula IV or V ##STR2## where R.sup.

Abstract: Catalysts comprising iron and potassium and, if desired, further elements, which catalysts are suitable for dehydrogenating hydrocarbons to give the corresponding olefinically unsaturated hydrocarbons, are prepared by calcining a finely divided dry or aqueous mixture of an iron compound with a potassium compound and, if desired, compounds of further elements in a first step that agglomerates having a diameter of from 5 to 50 .mu.m and formed from smaller individual particles are obtained and, in a second step, preferably after shaping, calcining it at from 300 to 1000.degree. C., with the maximum calcination temperature in the second step preferably being at least 30.degree. below the calcination temperature in the first step. The catalysts thus prepared are useful, in particular, for dehydrogenating ethylbenzene to give styrene.

Abstract: A process for preparing diarylethanes of the general formula I ##STR1## where R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are each hydrogen or C.sub.1 -C.sub.8 -alkyl, by reacting aromatic compounds of the general formula II ##STR2## where R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 have the abovementioned meanings, with styrenes of the general formula III ##STR3## where R.sup.1 has the abovementioned meanings, at from -20 to 300.degree. C. under from 1 to 100 bar in the presence of heterogeneous catalysts, wherein beta-zeolites or mordenites are used as heterogeneous catalysts.

Abstract: A process for the preparation of unsaturated cyclic ethers of the general formula I ##STR1## in which Z denotes --(CHR.sup.4).sub.q or --(CHR.sup.4).sub.q --O--q is 0, 1, 2 or 3 andR.sup.1, R.sup.2, R.sup.3, and R.sup.4 denote hydrogen or C.sub.1 -C.sub.4 alkyl from diols of the general formula II ##STR2## in which, R.sup.1, R.sup.2, and R.sup.3 have the aforementioned meanings, in the presence of a cobalt-containing supported catalyst, wherein the cobalt-containing supported catalyst used contains cobalt and a noble metal--selected from the group consisting of platinum, palladium, rhodium, iridium, ruthenium, osmium, rhenium, or mixtures thereof--in an atomic ratio of from 0.5:1 to 70000:1 on an inert support and optionally basic alkali metal and alkaline earth metal salts, scandium, vanadium, chromium, manganese, iron, nickel, copper, zinc, germanium, tin, lead, antimony, bismuth, or mixtures thereof and the reaction is carried out in the liquid phase at temperatures ranging from 150.degree. to 300.degree.

Abstract: A process for the deoxygenation of organic oxo compounds, in particular phosphine oxides to phosphines and nitrobenzene to aniline, with reduced redox catalysts in a non-steady-state reaction with decoupled reductive regeneration of the redox catalyst entails the redox catalyst being reduced to a lower oxidation state and being reused for the deoxygenation.