Abstract: An extractive distillation process is provided for the separation of phenol and/or cresol from mixtures with high boiling oxygenated compounds such as alkanols, alkanones, cycloalkanones, cycloalkanols, aryl alcohols, aryl ketones or mixtures thereof that have a boiling point of at least about 175.degree. C. The process involves distilling the phenol and/or cresol-high boiling oxygenated compound mixture in the presence of at least one extractive solvent comprising a substituted phenol and/or substituted cresol that has a boiling point between about 195.degree. C. and about 400.degree. C.

Abstract: In the purification of thionyl chloride by addition of sulphur and distillation in the presence of a catalyst, the improvement which comprises effecting the distillation in the presence of an aluminum compound as the catalyst. Advantageously the aluminum compound is aluminum chloride, the sulphur is added in about 2.5 to 7% by weight based on thionyl chloride, the aluminum chloride is in admixture with sulphur monochloride in about 0.01 to 5% by weight calculated as aluminum and based on thionyl chloride, and prior to distillation the mixture of crude thionyl chloride, sulphur and aluminum chloride is heated to between about 50.degree. and 60.degree. C. for about 10 to 60 minutes. The resulting thionyl chloride is of extremely high purity.

Abstract: Ethyl acetate cannot be completely removed from ethanol and water mixtures by distillation because of the presence of the minimum ternary azeotrope. Ethyl acetate can be readily removed from mixtures containing it, ethanol and water by using extractive distillation in which the extractive distillation agent is a higher boiling oxygenated of nitrogenous organic compound or a mixture of these. Typical examples of effective agents are: dimethylsulfoxide, glycerine and diethylene glycol, 1-naphthol, hydroquinone and N,N-dimethylformamide.

Abstract: Vinyltoluene is separated from close-boiling, olefinically unsaturated alkylaromatic compounds by extractive distillation. For example, vinyltoluene is separated from cis-.beta.-methylstyrene, and from .alpha.-methylstyrene by extractive distillation using .gamma.-butyrolactone as the extracting agent.

Abstract: Process for separating water from a gas mixture, obtained in the manufacture of vinyl acetate by reacting ethylene with acetic acid and oxygen in contact with catalysts containing palladium or palladium compounds in the gaseous phase said gas mixture consisting essentially of acetic acid, vinyl acetate, water, carbon dioxide and ethylene, wherein(a) the gas mixture leaving the reaction zone is condensed to give a condensate containing the major portion of acetic acid, vinyl acetate and water and(b) an acetic acid solution containing the residual amount of vinyl acetate and water being prepared by absorption of the non-condensed gas in acetic acid, is characterized in that(c) the condensate obtained in step (a) and the solution obtained in step (b) are introduced separately from each other into the same distillation column, the feeding point of the condensate being above the feeding point of the solution, the water is distilled off at the head of said column as azeotrope together with the vinyl acetate and(d)

Abstract: An improvement of a method for purifying 1,2-dichloroethane by passing through a distillation column a crude 1,2-dichloroethane produced by oxychlorination of ethylene with at least one of a crude 1,2-dichloroethane produced by direct chlorination of ethylene and a crude uncracked 1,2-dichloroethane recovered in thermal cracking of 1,2-dichloroethane, the improvement which comprises feeding the oxychlorination-produced 1,2-dichloroethane to an upper plate of the distillation column than a plate of the column to which at least one of the direct chlorination-produced 1,2-dichloroethane and the uncracked 1,2-dichloroethane is fed, and recovering 1,2-dichloroethane as a bottom product.

Abstract: A process for the purification of crude thionyl chloride wherein the crude thionyl chloride is distilled in the presence of sulfur and a sulfur-aluminum chloride catalyst to convert the impurities, sulfuryl chloride and sulfur dichloride and remove them from the distillate of thionyl chloride. The thionyl chloride collected will contain less than 0.01% sulfuryl chloride, less than 0.1% sulfur monochloride and less than 0.01% sulfur dichloride.

Abstract: A process for isolating a conjugated diolefin from a C.sub.4 - or C.sub.5 -hydrocarbon mixture containing the diolefin, by single-stage or multi-stage extractive distillation using a selective solvent, wherein the selective solvent is a solvent mixture which comprises(a) from 50 to 99 percent by weight of a selective solvent boiling at from 140.degree. C. to 260.degree. C. and(b) from 1 to 50 percent by weight of an organic solvent boiling at from 45.degree. C. to 125.degree. C.

Abstract: Ethylbenzene and para-xylene and/or meta-xylene are difficult to separate by distillation because they boil only 2.3 C..degree. and 3.1 C..degree. apart. Ethylbenzene can be readily separated from the xylenes by using extractive distillation in which the extractive distillation agent is a mixture of pentachlorophenol admixed with certain chlorinated and/or oxygenated organic compounds boiling higher than the xylenes. A typical mixture comprises pentachlorophenol, benzene hexachloride and 1,2,4-trichlorobenzene.

Abstract: Ethylbenzene and para-xylene and/or meta-xylene are difficult to separate by distillation because they boil only 2.3 C..degree. and 3.1 C..degree. apart. Ethylbenzene can be readily separated from the xylenes by using extractive distillation in which the extractive distillation agent is a mixture of oxygen-containing organic compounds boiling higher than the xylenes. The mixture typically includes phthalic anhydride and maleic anhydride with or without a solvent.

Abstract: Indene is separated from close boiling, olefinically unsaturated alkylaromatic compounds by extractive distillation. For example, indene is separated from trans-.beta.-methylstyrene, and from 2-, 3- and 4-methylstyrene by extractive distillation using 1-methyl-2-pyrrolidone as the extracting agent.

Abstract: A process for isolating a conjugated diolefin from a C.sub.4 - or C.sub.5 -hydrocarbon mixture containing the diolefin, by single-stage or multi-stage extractive distillation using a selective solvent, wherein the selective solvent is a solvent mixture which comprises(a) from 1 to 99 percent by weight of an N-alkyl-substituted lower aliphatic acid amide or of an N-alkyl-substituted alicyclic acid amide having 5 ring members and(b) from 1 to 99 percent by weight of an lower aliphatic carboxylic acid ester or carbonic acid ester boiling at from 30.degree. C. to 200.degree. C.

Abstract: The separation of butadiene-1,3 from other C-4 hydrocarbons of lesser degree of unsaturation by extractive distillation with alkoxynitrile or aqueous alkoxynitrile as selective solvent is carried out with improved selectivity, without appreciable formation of butadiene-1,3 polymer and with consequent savings in energy by adding to the alkoxynitrile or aqueous alkoxynitrile an organic cosolvent which is dimethyl sulfoxide, sulfolane, butyrolactone, N-methyl pyrrolidone, morpholine, or trimethyl phosphate and/or an inhibitor which is 2,4-dinitrophenol or 2,4-dinitro-ortho-cresol. The organic cosolvent is present in the selective solvent composition in an amount of 5 to 30 percent by weight and the inhibitor in an amount of 0.05 to 0.6 percent by weight.

Abstract: Formation of butadiene-1,3 polymer during the extractive distillation of a C-4 hydrocarbon mixture to separate and purify butadiene-1,3 using a solvent composition in which an alkoxynitrile is present in a proportion of 50-99 percent by weight, is decreased through inclusion in the solvent of a synergistic combination of 2,4-dinitrophenol and phosphoric acid, each in a proportion of 0.05 to 0.5 percent by weight.

Abstract: A method of inhibiting the polymerization of styrene which comprises mixing with the styrene a minor but effective quantity of an inhibitor compound selected from the group consisting of 2-methylbenzoquinone-4-oxime, 2,3,5-trimethylbenzoquinone-4-oxime and mixtures thereof.

Abstract: Phenol-, cyclohexanone-, and cyclohexylbenzene-containing mixtures are extractively distilled to provide an overhead of cyclohexanone substantially free of phenol and cyclohexylbenzene and a bottoms containing phenol and cyclohexylbenzene, substantially free of cyclohexanone by employing a nitrile solvent.

Abstract: In order to prevent corrosion of the apparatus in extraction and extractive distillation processes where N-substituted morpholine is employed as the selective solvent an additive is added to the solvent which additive consists of (a) phosphoric acid, (b) a salt thereof, (c) a vanadium compound, (d) a molybdenum compound or (e) a mixture of two or more of these compounds, the addition being effected in an amount of about 0.005 to 0.02% by weight of the morpholine solvent.

Abstract: An improved process for recovering phenol from phenol-water mixtures by distillation is provided by carrying out the distillation in a manner which avoids the normal phenol-water azeotropic limitation by introducing a ketone-hydrocarbon mixture into the upper section of a fractional distillation column used for the recovery. Mixtures of benzene or lower alkyl substituted benzene with lower ketones are employed in the process.

Abstract: A method of separating proximate boiling-point hydrocarbons using solutions of monovalent copper salts in solvents, said solvents being alkyl-substituted amides and alkyl esters of phosphorus-containing acids having a P.dbd.O group, N-alkyl-substituted amides of carboxylic acids, N-alkyl-substituted lactams, dialkyl sulphoxides, alkoxynitriles and N-alkyl-substituted aminonitriles. The method can be used for separating hydrocarbons from small quantities of acetylene compounds and cyclopentadiene.Large quantities of acetylene compounds are separated from the mixture of proximate boiling-point hydrocarbons by contacting the mixture with said solvents containing no salts of monovalent copper.

Abstract: Styrene is recovered from a styrene-rich stream by complexing with a copper(I) sulfonate. The complex is treated to displace the styrene from the complex.

Abstract: A process for extracting essentially pure unsymmetrical dimethyl hydrazine UDMH) from a solution containing UDMH, water, and other volatiles and non-volatiles, comprises charging a distillation stillpot with the UDMH solution, mixing into the solution sufficient caustic sodium hydroxide so as to cause the solution to separate into a two layer system, mixing isopropanol into the two layer system, and distilling off the essentially pure UDMH distillate.

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: In the extractive distillation of C.sub.5 hydrocarbons with different degrees of unsaturated using acetonitrile, an increase in the selectivity of acetonitrile is obtained when also using with acetonitrile small amounts of at least one compound selected from the group consisting of dimethylformamide, dimethylsulfoxide, morpholine, furfural, N-methylpyrrolidone, 3-methoxypropionitrile, gamma-butyrolactone, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and diethylene glycol monoethyl ether.

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: 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 combination of phenothiazine and a phenolic compound, preferably tert-butylcatechol (TBC), as a polymerization inhibitor system in the presence of oxygen.

Abstract: Formic acid is removed from acetic acid substantially free of halide impurities but containing small amounts of formic acid by contacting the acid with a compound of hexavalent chromium and recovering the purified acid from the resulting mixture by distillation, ion-exchange, or the like. In a preferred embodiment, the acid to be purified is distilled in the presence of a solution of the hexavalent chromium compound, the purified acid being obtained as the overhead product while the bottoms stream contains the reduced chromium compound. With the preferred chromium trioxide as treating agent, this compound can be recovered for re-use by adding a strong mineral acid to the bottoms stream from the distillation, electrolytically oxidizing the chromium compound contained therein, and separating chromium trioxide from the strong mineral acid solution.

Abstract: The present invention relates to a process for inhibiting the polymerization of styrene monomers during the purification of crude styrene.

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

Abstract: Phenol, cyclohexanone, and cyclohexylbenzene containing mixtures are extractively distilled to provide overhead of cyclohexylbenzene and cyclohexanone and a kettle product substantially free of cyclohexylbenzene by employing a dialkyl and/or a dicycloalkyl phthalate. Co-agents or modifiers, e.g., sulfolane, polyalkylene glycols, etc., are advantageously used in some instances.

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: 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.