Abstract: A process is provided for the preparation of aqueous silica sols having a particle size of 27 to 72 nm. by adding fresh acidic silica sol into the reactors of a multi stage cascade reactor wherein the reactors contain aqueous solution of colloidal silica sol of a pH of 8 or above. Each successive stage of the cascade reactor is supplied with overflow from the preceding stage. Alkaline compounds, such as alkaline sodium silicate solution, alkaline potassium silicate solution, sodium hydroxide solution or potassium hydroxide solution, are introduced into the first reactor or first reactors so that a pH value in the range of 8 to 12.5 is established in the reactors.

Abstract: The present invention relates to a process for producing low-salt silica sol dispersions in low-boiling alcohols and to the use of the organosols obtained by this process for the production of coatings on metallic and nonmetallic substrates.

Abstract: This invention relates to a process for the production of symmetrical trialkyl phosphites, which are also known as phosphorus acid trialkyl esters, from phosphorus trichloride and alcohol in the presence of an auxiliary base as an acid-binding agent and a solvent.

Abstract: Use of diethyl dodecylphosphonate (DEDP) for the extraction of acids and metal salts from aqueous solutions.

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: This invention relates to an improved process for the production of 2-phosphono-butane-1,2,4-tricarboxylic acid (PBTC) and the alkali metal salts thereof, in which process dialkyl phosphite, preferably dimethyl or diethyl phosphite, and ethene-1,2-dicarboxylic acid dialkyl ester, in particular the dimethyl or diethyl ester of maleic acid and/or fumaric acid, are initially reacted in the presence of a basic catalyst to yield a phosphonosuccinic acid tetraalkyl ester, the resultant ester is thereupon reacted without further working up with acrylic acid alkyl ester, preferably methyl or ethyl acrylate, in the presence of an alkaline catalyst and the reaction product obtained in this manner is saponified without further working up to yield PBTC or the alkali metal salts thereof. The product when mixed with bleaching lye exhibits reduced chlorine depletion.

Abstract: A process for the recovery by distillation of tributyl phosphate (TBPO) from spent hydraulic oils, which are employed particularly in aircraft used for civilian air traffic.

Abstract: In the preparation of dimethylamine-borane by reacting an alkali metal or alkaline earth metal borohydride with a dimethylammonium salt, the improvement which comprises effecting the reaction in a liquid mixture comprising dimethylamine as a solvent and an additional organic solvent.

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: Process for the production and concentration of alkaline silica sols containing nonaggregated, spherical SiO.sub.2 particles with a diameter of .gtoreq.1 nm starting with SiO.sub.2 concentrations of 4-8% by weight, using microporous membrane filters.

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

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: 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: An aqueous solution for conditioning tooth or bone substance containing phosphono carboxylic acids wherein the solution has a pH in the range 1 to 8.

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: The present invention relates to a process for the preparation of alkali metal salts of 2-phosphonobutane-1,2,4-tricarboxylic acid, characterized in that 2-phosphonobutane-1,2,4-tricarboxylic acid penta-alkyl esters or partial esters are reacted with an aqueous alkali metal hydroxide solution in a ratio of from 0.5 to 0.76 mol, preferably from 0.6 to 0.7 mol of alkali metal hydroxide per mol of ester function at temperatures from 20.degree. to 200.degree. C. in a one-shot process.

Abstract: The new polyphosphonates, which are highly branched through polyfunctional phosphorus compounds, are suitable for use as moldings, fibers or films and as flameproofing agents and stabilizers in plastics. The new highly branched polyphosphonates show high resistance to thermal ageing and ensure good processability coupled with high migration resistance at elevated in-use temperatures.

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,