Abstract: Polymerizable compounds are prepared and/or worked up using at least one liquid ring pump by a process in which a working liquid which contains a material stream from the preparation and/or working-up of the polymerizable compound is used in a liquid ring pump.

Abstract: An inhibitor mixture containing, as components, a) at least one nitroxyl radical (derivative), b) at least one phenol (derivative) and c) at least one chemical compound which contains at least one phosphorus atom which has the oxidation state +3 is preferably used for stabilizing compounds capable of free radical polymerization.

Abstract: A process for preparing acrylic acid and/or acrylates which comprises the following stage A and, if desired, B and C: A: cooling a gaseous reaction mixture which comprises acrylic acid and is obtained in the gas-phase oxidation to prepare acrylic acid, using oligomeric acrylic acid or a mixture of acrylic acid and oligomeric acrylic acid, to give a gaseous mixture comprising acrylic acid and a quench bottom product which comprises oligomeric acrylic acid; B: separating the gaseous mixture comprising acrylic acid, to give a low-boiling fraction, a crude acrylic acid, and a bottom product, which comprises oligomeric acrylic acid; C: esterifying the crude acrylic acid obtained in stage B by means of one or more alkanols.

Abstract: In a process for preparing acrylic acid, an acrylic acid-containing product gas mixture obtained by catalytic gas phase partial oxidation of a C3 precursor of acrylic acid, after direct cooling with a quench liquid, is fractionally condensed in a separating column provided with internals, rising into itself with sidestream takeoff of crude acrylic acid, and the acrylic acid oligomers which form are dissociated and the resulting dissociation gas is subjected to a countercurrent rectification before it is recycled.

Abstract: A water lance blower for cleaning heat installations is disclosed. A water lance linked with a water feed conduit system is swivel-mounted with its orifice disposed in a hatch. The water lance can blow a jet of water through the heating installation in operation and through which flames and/or flue gases are guided to wall areas that can be reached from the hatch. The water lance blower is provided with a drive system with at least two drive units that control the water lance, and with a holding device that fastens the water lance blower onto the heating installation. Further, parts of the water feed conduit system are integrated onto the holding device, thereby substantially limiting the size of the water lance blower to the swivel range of the water lance.

Abstract: In a process for the fractional condensation of an acrylic acid-containing product gas mixture of a gas-phase partial oxidation of C3 precursors of acrylic acid with molecular oxygen under heterogeneous catalysis, the separation column used contains both dual-flow trays and hydraulically sealed cross-flow trays as baffles having separation activity.

Abstract: An ester of an &agr;,&bgr;-unsaturated carboxylic acid is prepared by reacting the carboxylic acid with a C6-C12-alkanol, cyclopentanol or cyclohexanol in the presence of an acidic esterification catalyst and of an entraining agent for removing the water of reaction formed in the esterification, by a process in which the entraining agent used is the olefin on which the alkanol is based.

Abstract: In a process for esterifying (meth)acrylic acid with an alkanol in the presence of an esterification catalyst, in which unconverted starting compounds and (meth)acrylic ester to be formed are separated off by distillation and an oxyester-containing bottom product is formed, the bottom product is first separated off and then the oxyesters contained in it are cleaved in the presence of a relatively long-chain alkylbenzenesulfonic acid at elevated temperatures.

Abstract: Flexible polyurethane foams are prepared by reacting organic and/or modified organic polyisocyanates (a) with a polyetherol mixture (b) and, if required, further compounds (c) having hydrogen atoms reactive toward isocyanates, in the presence of water and/or other blowing agents (d), catalysts (e) and, if required, further assistants and additives (f), by a process in which the polyetherol mixture (b) consists of b1) at least one polyetherol which is at least difunctional, has an OH number of from 20 to 100 mg KOH/g and is based on propylene oxide and/or butylene oxide and ethylene oxide, having an ethylene oxide content of more than 40% by weight, based on the total amount of alkylene oxide used, and, if required, further polyetherols which are at least difunctional, are based on propylene oxide and/or butylene oxide and ethylene oxide and have an OH number of from 20 to 160 mg KOH/g and b2) at least one difunctional to hexafunctional polyetherol based on propylene oxide and/or butylene oxide and having an

Abstract: Plant parts which are used for the production or processing of (meth)acrylic esters are cleaned by (a) emptying the plant parts, (b) flushing the plant parts with aqueous 5 to 50% strength by weight alkali metal hydroxide solution, (c) removing the alkali metal hydroxide solution from the plant parts, (d) if required, washing the plant parts with water and (e) if required, drying the plant parts.

Abstract: A process for preparing acrylic acid and/or acrylates, which comprises stage A with or without stages B and C: A: cooling a gaseous reaction mixture which comprises acrylic acid and is obtained in the gas-phase oxidation to prepare acrylic acid, using an inert high-boiling solvent, to give a gaseous mixture comprising acrylic acid; B: separating the gaseous mixture comprising acrylic acid to give a low-boiling fraction, a crude acrylic acid, and a bottom product, and C: esterifying the crude acrylic acid obtained in stage B by means of one or more alkanols to give an esterification mixture comprising one or more acrylates and one or more acetic esters.

Abstract: Free radical polymerizations immediately terminated by a process comprising the addition of an inhibitor solution which contains phenothiazine and at least 50% (w/w) N-alkylpyrrolidone to a system undergoing free radical polymerization, wherein the inhibitor solution also contains p-methoxyphenol (MEHQ).

Abstract: In a process for stabilizing chemical compounds having at least one ethylenically unsaturated bond to undesired free radical polymerization, a nitroxyl radical and a chemical compound containing phosphorus in chemically bonded form are added to the unsaturated compound present as pure substance or as a component of a mixture.

Abstract: The process for the esterification of (meth)acrylic acid with an alkanol in the presence of an esterification catalyst, in which unconverted starting compounds and the (meth)acrylate to be formed are separated off by distillation and an oxyester-containing bottom product is formed and is separated off, and (a) in the bottom product separated off, the oxyesters present are cleaved, if required after the addition of (meth)acrylic acid and/or oligomeric (meth)acrylic acid, directly in the presence of acid catalysts differing from (meth)acrylic acid and/or oligomeric (meth)acrylic acid, and the cleavage products are removed, a cleavage residue remaining, or (b) the oxyesters are first removed by distillation from the cleavage product separated off, a distillation residue remaining, and the oxyesters removed are cleaved, if required after addition of (meth)acrylic acid and/or oligomeric (meth)acrylic acid, in the presence of acid catalysts differing from (meth)acrylic acid and/or oligomeric (meth)acrylic acid, a

Abstract: An arrangement is provided for digital transmission of information via lines between a line termination (1) of a telecommunication network and subscribers (Tln) connected to the line termination. At least one terminal of a subscriber (Tln) is connected to a network termination (2) via an electric line (L3). The network termination (2) is connected to the line termination (1) via a line (L2) having metallic conductors. The line termination (1) has a voltage source (SV) for supplying power to itself and to the network termination (2) and the subscriber (Tln) terminals. For increased reliability during operation, two separate power supply units (SVE1, SVE2) are arranged in the network termination (2). One of the two separate power supply units (SVE1, SVE2) powers active components of the network termination (2) and the other of the two separate power supply units (SVE1, SVE2) powers the subscriber (Tln) terminals.

Abstract: In a process for the preparation of acrylic acid, a product gas mixture obtained by catalytic gas-phase oxidation of a C3-precursor of acrylic acid and containing acrylic acid is directly cooled with a quench liquid and then subjected to fractional condensation in a separation column provided with baffles, said product gas mixture ascending into itself and a crude acrylic acid being removed via a side take-off, and the acrylic acid oligomers formed are cleaved and recycled.

Abstract: An article having a metallic surface treated with polymeric complexing agent is described. Particularly suitable polymeric complexing agents are phosphonoalkylated polyethyleneimines and/or carboxyalkylated polyethyleneimines and/or vinylimidazole polymers. As a rule, the treated metallic surface forms the total inner surface or a part of the inner surface of a process apparatus or of a container. The surface is protected by the treatment, in particular from the adhesion of polymer.

Abstract: An inhibitor mixture containing, as components, a) at least one nitroxyl radical (derivative), b) at least one phenol (derivative) and c) at least one chemical compound which contains at least one phosphorus atom which has the oxidation state +3 is preferably used for stabilizing compounds capable of free radical polymerization.

Abstract: Pure acrylic acid is stored and/or transported by a process in which the pure acrylic acid is stored and/or transported as liquid aqueous solution at ≦15° C.

Abstract: A process for the continuous recovery of (meth)acrylic acid from a liquid starting mixture containing (meth)acrylic acid, a high-boiling organic solvent and low boilers, medium boilers and high boilers is proposed, the mixture being separated into a first part-stream (a), which, in addition to (meth)acrylic acid, contains the low boilers and a part each of the medium boilers and high boilers, and a second part-stream (b), which contains the predominant part of the (meth)acrylic acid and is completely or virtually completely free of low boilers, and the (meth)acrylic acid being recovered from the part-stream (b).