Abstract: A mixture of C.sub.4 -hydrocarbons is extractively distilled with sulfolane and acetone or methylethyl ketone as the selective solvent; the rich solvent containing 1,3-butadiene and vinylacetylene is stripped and a small quantity of the ketone is allowed to leave overhead. Thereby the further fractionation of the stripper overhead results in a very efficient separation of 1,3-butadiene and vinylacetylene.

Abstract: Dimethyl carbonate is obtained pure, from its solutions in methanol, by extractive distillation carried out with a temperature of from 60.degree. C. at the top to 250.degree. C. at the bottom of the column and employing, as the extractant, an aprotic organic liquid which is substantially inert toward dimethyl carbonate, boils at above 100.degree. C. at standard pressure, is miscible with dimethyl carbonate in all proportions and has a dielectric constant .epsilon. of from 4 to 90 and a dipole moment .mu. of from 1.5 to 5 Debye.

Abstract: In an oxidation process for converting methacrolein to methacrylic acid, methacrylic acid is recovered by cooling and condensing the effluent from the oxidation, followed by azeotropic distillation of the condensate with a suitable solvent, such as methyl n-propyl ketone. The condensed effluent contains methacrylic acid and water as the major components along with by-product acetic acid, a minor amount of unreacted methacrolein and impurities. Substantially dry crude methacrylic acid is separated as a bottom product from the azeotropic distillation and an azeotrope of water and the solvent is taken overhead and condensed. After condensation, solvent-rich and water-rich phases form and are separated. The solvent-rich phase is returned to the distillation column as a reflux, while the water-rich phase is sent to a stripping column for recovery of residual solvent. Water is withdrawn from the bottom of the stripping column and recycled or discarded, as desired.

Abstract: Acetylenic hydrocarbons are removed from a C.sub.4 - or C.sub.5 - hydrocarbon mixture containing a C.sub.4 - or C.sub.5 - diolefin respectively. The feedstock (e.g. a C.sub.4 - or C.sub.5 - cut from an ethylene plant) is extractively distilled to remove paraffins and mono-olefins in the raffinate, using acetonitrile (ACN), dimethyl formamide (DMF), furfural, acetone, dimethylacetamide or N-methyl-2-pyrrolidone mixed with 0-12 weight percent water as the extraction solvent. The bottoms from this first extractive distillation is subjected to a second extractive distillation in which virtually acetylenes-free solvent is used. Isoprene is withdrawn as the distillate with substantially reduced acetylenes content. The bottoms of the second extractive distillation is split three ways. Two streams are handled conventionally (recycle and heavies removal). The third is stripped free of acetylenes so that it may be used as solvent in the second extractive distillation.

Abstract: Disclosed is a process for the distillation of readily polymerizable vinyl aromatic compounds which comprises subjecting such compounds to distillation conditions in the presence of an effective amount of a polymerization inhibitor selected from the group consisting of 3-nitro-2, 5-cresotic acid and 3-nitro-2, 5-cresotaldehyde.

Abstract: A method for the partial or total separation by extractive distillation of C.sub.1 to C.sub.3 clorinated aliphatic hydrocarbons from mixtures of at least two such chlorinated hydrocarbons. The mixture of the chlorinated hydrocarbons is distilled in the presence of one or more other organic compounds having a boiling temperature higher than the substances to be separated, and selected from the group comprising saturated polyols, ethylene carbonate, propylene carbonate, dimethyl formamide, furfural, N-methylpyrrolidone, cyclohexanone, dimethylsulfoxide and, preferably, sulfolane and alkylsulfolanes in which the alkyl group is C.sub.1 or C.sub.2 ; use of this method for the separation of mixtures containing or essentially consisting of trichlorethylene and 1,2-dichloroethane.

Abstract: A process is described for improving the synthesis of 4-oxocapronitrile by adding an inert solvent to the atmospheric pressure distillation of the reaction mixture so that the temperature of said distillation is maintained below about 195.degree. C.

Abstract: The prior art discloses a number of polymerization inhibitors for acrylic acid, acrylates and derivatives thereof, but such polymerization inhibitors have low vapor pressures. Consequently, when acrylic acid is vaporized, it tends to polymerize on cooling surfaces causing undesirable deposits on storage vessels and the like. However, when a polymerization inhibiting amount of 2,4-pentanedione is added to the monomer, the polymerization of acrylic acid on cooling surfaces is inhibited.

Abstract: Fluid mixture of acetone and at least one hydrocarbon containing four-carbon atoms is separated by fractional distillation at a pressure low enough to eliminate formation of an azeotrope and a corresponding temperature.

Abstract: Acetone containing less than 0.2 weight percent water is produced in an extractive distillation of acetone containing appreciable quantities of water by utilizing isopropyl alcohol as the extracting agent.

Abstract: The invention relates to an improved process for removing water, under elevated temperature, from aqueous gel of water soluble polymer, such as polymer or copolymer of acrylamide and/or quaternary ammonium salts of dialkylaminoamlkylmethacrylate, to prevent from the deterioration of polymer properties. The process is accomplished by addition of polyhydric phenols, benzoquinones or derivatives thereof prior to removal of water.

Abstract: A C.sub.4 -hydrocarbon feedstream containing butenes, butadiene, and vinylacetylene is subjected to a first extractive distillation with a selective solvent to remove butenes and a first portion of vinylacetylene as the extract; by the extraction with a minor quantity of methylethyl ketone in the selective solvent in this step, it has been found that a major portion of the vinylacetylene can be rejected, together with the butenes in the rich extract and that simultaneously the quantity of butadiene extracted could be considerably reduced; in a second extractive distillation the butadiene-rich raffinate of the first extractive distillation is further purified by extractive distillation using a mixture of sulfolane and methylethyl ketone as the solvent; after solvent stripping, the butadiene stream is finally purified in a fractionation step, wherein further vinylacetylene is removed.

Abstract: A mixture of methylethylsulfone and at least one compound from the group including methylethylketone, acetone, and tetrahydrofuran is employed as a selective solvent in extractive distillation process for separation of diolefins from olefins.

Abstract: Butadiene is produced in relatively pure form by an oxidative dehydrogenation process in which a crude butadiene stream comprising butadiene, butylenes, vinyl acetylene and propylene is first extractively distilled with an extractant consisting of a sulfolane/acetone mixture. From a purified stream consisting essentially of butadiene and vinyl acetylene, the vinyl acetylene in a second extractive distillation step is removed using a sulfolane/acetone mixture as the extractant to produce a pure butadiene stream.

Abstract: In a process of extractive distillation, the combination of operating with two liquid phases in at least the uppermost trays of the column, preferably while maintaining the column operation at substantially an optimum reflux ratio, results in increased efficiencies and minimum requirements for selective solvent.

Abstract: A method of partially or totally separating chlorinated aliphatic C.sub.1 to C.sub.3 hydrocarbons from mixtures of at least two of the chlorinated hydrocarbons by extractive distillation.The mixture of the chlorinated hydrocarbons is distilled in the presence of one or more third organic compounds having a boiling point higher than that of the substances to be separated, selected from the group comprising methyl, ethyl, normal propyl and isopropyl mono and di-chloroacetates; benzyl alcohol; salicylaldehyde, benzaldehyde, n-heptanal, methylisobutylketone, tetramethylurea, .gamma.-butyrolactone; normal propyl, isopropyl, normal, secondary and tertiary butyl acetylacetates; diethyl oxalate, dimethyl succinate and preferably methyl and ethyl acetylacetates; acetic anhydride, N-formyl-morpholine, 2-chloro ethanol, hexamethylphosphotriamide, dimethyl sulphate and normal tributyl and triisobutyl phosphates.

Abstract: Hydrocarbons having different degrees of saturation are separated by extractive distillation using selective solvent comprising a mixture of dimethylsulfone, methylethylketone and sulfolane.

Abstract: A mixture of n-butane and acetone is effectively separated by liquid-liquid extraction or extractive distillation using a sulfolane as the extractive solvent.

Abstract: The present invention relates to the use of quinone alkides as polymerization inhibitors in a styrene purification process. The inhibitors are prepared by oxidizing hindered phenols to the corresponding quinone alkide.

Abstract: An extractive distillation cosolvent comprising furfural-alicyclic or acyclic C.sub.5 -C.sub.8 ketone having a boiling point of 130.degree.-180.degree. C., for example cyclohexanone, gives 20% or more improved hydrocarbon solubility and provides a more efficient process for separation of C.sub.4 and C.sub.5 hydrocarbons of varying degrees of saturation.

Abstract: A method for extraction of acrylic acid and/or methacrylic acid from a solution containing the same by treating the said solution with an organic solvent, which is characterized by using a mixture of methylethylketone and a xylene as the organic solvent. By such method, the extraction of acrylic acid and/or methacrylic acid is accomplished efficiently and economically.

Abstract: A method of inhibiting the thermopolymerization of isoprene or butadiene in the process of isolation thereof by extractive distillation from a mixture of hydrocarbons obtained in dehydrogenation of isopentane and butane. The method of inhibiting includes, prior to the introduction of said mixture of hydrocarbons and a polar extractant into an extractive distillation metal apparatus, treating the surface of the apparatus with a 1-25% aqueous solution of passivators, viz. nitrites, sulphites or phosphates of alkali metals at a temperature of 20.degree.-100.degree.C. The mixture of hydrocarbons and the polar extractant with an inhibitor of isoprene or butadiene thermopolymerization introduced into the polar extractant are then fed into said apparatus in an amount of 0.01-1% of the extractant weight. The present method makes it possible to reduce markedly the formation of isoprene and butadiene and, hence, to prevent the plugging of the extractive distillation apparatuses with the aforementioned thermopolymers.