Abstract: The present invention relates to a process for preparing alkyl halosilanes by reacting a contact material which comprises, in addition to silicon, at least one copper-containing compound as catalyst and at least one promoter, with an alkyl halide.

Abstract: A method for the decomposition of chromium ore in a directly heated revolving tube is described, in which oxygen-containing gases are introduced into the revolving tube by means of below-bed nozzles.

Abstract: The present invention relates to novel polyether-substituted compounds of imides and their use as surface-active agents.

Abstract: A method for manufacturing alkali chromates by the reacting of chromium ore with alkali compounds and oxidation in an atmosphere containing at least 50% oxygen is described, in which the mixture consisting of chromium ore, alkali compound and optionally leaning materials is heated in a first stage in an atmosphere containing not more than 5 vol. % oxygen to a temperature between 1000.degree. and 1 400.degree. C., and in a second stage is oxidized at a lower temperature of 900.degree. to 1 070.degree. C. with supply of an atmosphere containing at least 50% oxygen.

Abstract: Fluoroalkyl- and fluoroaryl-group-containing imides and their salts of general formula (I) ##STR1## wherein R.sub.F is a fluoroalkyl group with 1 to 18 carbon atoms, a fluoroaryl group with 6 to 12 carbon atoms or a mixed fluoroalkylaryl group with 7 to 18 carbon atoms, wherein the carbon chain can also be interrupted by oxygen atoms,R.sub.H is an alkyl group with 1 to 30 carbon atoms, an aryl group with 6 to 12 carbon atoms or a mixed alkylaryl group with 7 to 30 carbon atoms, wherein the carbon chain of the group can also be interrupted by oxygen, nitrogen or sulphur atoms,Y.sub.1 and Y.sub.2 independently of each other represent a ##STR2## X is a hydrogen cation or a uni- or multivalent cation, m is a whole number from 0 to 6, andz is a whole number from 1 to 7 corresponding to the charge of the cation X.

Abstract: The present invention relates to fluorinated carboxylic acid esters of phosphono- and phosphinocarboxylic acids containing hydroxyl and/or mercapto groups, their use as waterproofing and/or oil-repellency agents, and a method for their preparation.

Abstract: The present invention relates to fluorinated carboxylic acid esters of phosphonocarboxylic acids containing acrylate and/or methacrylate groups, their use as waterproofing or oil-repellency agents, and a method for their preparation.

Abstract: The present invention relates to novel polyether-substituted compounds of imides and their use as surface-active agents.

Abstract: The invention relates to a process for purifying industrial anhydrous hydrogen fluoride by means of oxygen difluoride.

Abstract: The invention relates to an improved process for the production of liquid amine adducts of fluorine-containing amides, in which the compounds are synthesized in the absence of solvents in two process steps without the synthesis of intermediate products.

Abstract: The invention relates to a process for the preparation of perfluorobutylsulphonyl fluoride by electrochemical fluorination of butylsulphonyl fluoride, tetrahydrothiophene-1,1-dioxide (sulpholane), 2,5-dihydrothiophene-1,1-dioxide (sulpholene) or mixtures of these in hydrogen fluoride.

Abstract: The present invention provides a process for the production of perfluoroalkylsulphonyl fluorides of the formula C.sub.n F.sub.2n+1 SO.sub.2 F with n=6-10 by electrochemical fluorination of alkylsulphonyl halides of the general formula C.sub.n H.sub.2n+1 SO.sub.2 X with n=6-10 and X=F, Cl, Br or I in hydrogen fluoride, which process is characterised in that electrodes are used which consist of nickel with a columnar structure or which are coated with nickel with a columnar structure as shown in FIG. 1.The invention also provides electrodes for the production of perfluoroalkylsulphonyl fluorides from the corresponding alkylsulphonyl halides by electrochemical fluorination in hydrogen fluoride, which electrodes are characterised in that they consist of nickel with a columnar structure or are coated with nickel with a columnar structure.

Abstract: The present invention relates to fluorinated carboxylic acid esters of phosphonocarboxylic acids or phosphinocarboxylic acids, and the use thereof as surface-active agents.

Abstract: In the production of perfluoroalkylsulfonyl fluorides by electrolytic fluorination of alkylsulfonyl fluoride, the electrolyte contains anhydrous hydrogen fluoride, an alkylsulfonyl fluoride, and at least one additional component selected from alkaline earth fluorides, alkali tetrafluoroborates, alkali hexafluorophosphates, hexafluorophosphoric acid, tetrafluoroboric acid, boron trioxide, boron trifluoride, or mixtures thereof.

Abstract: A process for the preparation of sodium dichromate and sodium dichromate solutions by alkaline oxidizing roasting of chromium ores, leaching resulting roast with water, adjustment of the pH to 7 to 9.5, removal of the insoluble constituents by filtration, a sodium monochromate solution containing 300 to 400 g/l of Na.sub.2 CrO.sub.4 being obtained, conversion of the monochromate ions of this solution into dichromate ions by addition of an acid and/or by electrolysis and/or by reaction with carbon dioxide under pressure and crystallization of sodium dichromate by concentration of this solution. The improvement wherein before the conversion into a sodium dichromate solution, the sodium monochromate solution is concentrated to contents of 700 to 1000 g/l of Na.sub.2 CrO.sub.4, the monochromatic ions, the solution is subsequently freed as far as possible from sodium sulphate by cooling to a temperature of below 0.degree. C.

Abstract: The invention relates to a process for the production of sodium dichromate and sodium dichromate solutions by oxidative roasting of chrome ores under alkaline conditions, leaching of the furnace clinker obtained with water or an aqueous chromate-containing solution, adjustment of the pH to from 7 to 9.5, removal of the insoluble constituents by filtration, a sodium monochromate solution being obtained, conversion of the monochromate ions of this solution into dichromate ions by acidification and crystallization of sodium dichromate by concentration of this solution, characterized in that the acidification is carried out with carbon dioxide under pressure with removal of sodium hydrogen carbonate, the remaining solution is then very largely freed from sodium monochromate by cooling to a temperature below 10.degree. C.

Abstract: A process for the production of chromic acid, comprisinga) dissolving ferrochrome in sulphuric acid, optionally with the addition of catholyte and/or anolyte overflow from the electrolysis,b) removing undissolved constituents by filtration,c) adding a reducing agent in a quantity more than equivalent to the quantity of iron(III) and chromium(IV) in the solution,d) precipitating chromium(III) hydroxide by raising the pH to about 4-6 by the addition of a base while maintaining the reducing conditions in the solution,e) separating the precipitated chromium hydroxide while maintaining the reducing conditions,f) working up the aqueous solution containing iron by oxidation; precipitating iron(III) hydroxide or iron(III) oxide and optionally isolating the sulphate in the solution as sodium sulphate, ammonium sulphate or calcium sulphate,g) dissolving the separated chromium hydroxide in chromic acid and optionally sulphuric acid where either a single solution in chromic acid is produced or two solutions are produced,

Abstract: A process for the preparation of alkali metal dichromates and/or chromic acid by electrolysis of alkali metal monochromate and/or alkali metal dichromate solution in electrolysis cells, the anode and cathode compartments of which are separated by cation exchange membranes, wherein the cation exchange membranes are single-layer membranes based on perfluorinated polymers having sulfonic acid groups as cation exchange groups, and an aqueous solution having a pH of 4 to 14 is produced in the cathode compartment of the cells.

Abstract: A dimensionally stable anode comprised ofa) an electrically conductive valve metalb) a conductive intermediate layer andc) an electrode coating of an electrocatalytically active substance, wherein the intermediate layer comprises one or more noble metals or their alloys which have been applied to the valve metal by deposition by electroplating from melts containing noble metal salts. This anode can be used in the production alkali metal dichromates and chromic acid by electrolysis of alkali metal monochromate and/or alkali metal dichromate solutions.

Abstract: A process for the production of chromic acid, comprising(a) dissolving ferrochrome in sulphuric acid and mother liquor from the subsequent crystallization of ammonium chrome alum, optionally with the addition of at least one of catholyte and anolyte overflow from the subsequent electrolysis,(b) removing undissolved constituents by filtration,(c) removing dissolved iron by the addition of at least one of ammonia and ammonium sulphate to the filtrate obtained, crystallizing iron ammonium sulphate and filtering,(d) crystallizing and filtering ammonium chrome alum from the remaining solution and returning the filtrate for dissolving ferrochrome in step (a),(e) dissolving the ammonium chrome alum in water,(f) precipitating and separating chromium-(III) hydroxide from the resulting solution by adding a base, optionally under reducing conditions,(g) dissolving the separated chromium hydroxide in chromic acid and optionally sulphuric acid so that either a single solution in chromic acid is obtained or two solutions a