Abstract: The separation by conventional distillation or rectification of methyl t-butyl ether from close boiling hydrocarbons is difficult because of the closeness of their vapor pressures. Methyl t-butyl ether can be readily separated from these by extractive distillation. Examples of effective agents are: from 1-pentene, dimethylsulfoxide; from cyclopentane, sulfolane and from n-pentane - cyclopentane mixtures, diethyl malonate.

Abstract: Hexane cannot be removed from hexane - vinyl acetate mixtures by distillation because of the minimum boiling azeotrope. Hexane can be readily removed from vinyl acetate by extractive distillation. Typical effective agents are phenol, 1-nitropropane and benzyl alcohol.

Abstract: A process for separating an aromatic from a mixture containing also nonaroma includes distilling off the nonaromatics from the top of the extractive distillation column as a top product, drawing the aromatic and selective solvent from the extractive distillation column and subsequently separating the selective solvent from the aromatic in a separator column. The extractive distillation column is provided with a separate top product distillation column for recovery of a selective solvent residue from the separated nonaromatics. The entry hydrocarbon mixture is heated prior to admission to the extractive distillation column by an indirect heat exchange with selective solvent drawn from the separator column and heated to a temperature of from 130.degree. to 150.degree. C.The heated entry hydrocarbon mixture is depressurized to form a liquid phase and a vapor phase and these phases are separately fed into the extractive distillation column, the vapor phase entry point being below the liquid phase entry point.

Abstract: Tetrachloroethylene cannot be completely separated from methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, 2-pentanol, 3-methyl-1-butanol or t-amyl alcohol by conventional distillation or rectification because of the minimum boiling azeotropes. Tetrachloroethylene can be readily separated from these alcohols by extractive distillation. A typical effective agent is dimethylsulfoxide.

Abstract: Anhydrous or substantially anhydrous formic acid is prepared by hydrolyzing methyl formate in the presence of a formamide and then obtaining the formic acid from the hydrolysis mixture by distillation, by a method in which the hydrolysis is carried out in the presence of 0.5-3 moles, per mole of methyl formate, of a water-soluble formamide of the general formula I ##STR1## where R.sup.1 and R.sup.2 are each alkyl or together form an alkylene group, giving a 5-membered to 7-membered ring, with the proviso that the sum of the carbon atoms in R.sup.1 and R.sup.2 is 5 or 6 and, in the case of an alkylene group, a carbon atom which is not directly bonded to the N atom can be replaced by an oxygen atom.

Abstract: 1,1,1-Trichloroethane cannot be completely separated from methanol, ethanol, n-propanol, isopropanol, 2-butanol or t-butanol by conventional distillation or rectification because of the minimum boiling azeotropes. 1,1,1-Trichloroethane can be readily separated from these alcohols by extractive distillation. A typical effective agent is dimethylsulfoxide.

Abstract: A method of separation of aromates from hydrocarbon mixtures by extractive distillation with a selective solvent, includes introducing a hydrocarbon mixture into the extractive distillation column, distillating out non-aromate components of the introduced hydrocarbon mixture from a head of the extractive distillation column, withdrawing aromates together with a used solvent from a sump of the extractive distillation column and supplying to a driving-out column, separating the aromates from the solvent in the driving-out column, withdrawing the aromates as a head product and the solvent as a sump product from the driving-out column, reintroducing the withdrawn solvent into the extractive distillation column, the withdrawing of the solvent from the driving-out column including withdrawing only part of the solvent with a high temperature required for the complete aromate driving-out from the sump of the driving-out column, while a rest of the solvent with a certain aromate content and a lower temperature is with

Abstract: Acetic acid cannot be easily removed from acetic acid - water mixtures by distillaton because of the closeness of their boiling points and the deviation from ideal solution behavior. Acetic acid can be readily removed from the mixtures containing it and water by using extractive distillation. Typical effective agents are sulfolane and adiponitrile.

Abstract: Tetracholorethylene cannot be completely separated from n-butanol, isobutanol or 2-butanol by conventional distillation or rectification because of minimum boiling azeotropes. Tetrachloroethylene can be readily separated from n-butanol, isobutanol or 2-butanol by extractive distillatiion. Typical effective agents are: for n-butanol, dipropylene glycol methyl ether; for isobutanol, dimethylsulfoxide and isobutyl butyrate; for 2-butanol, ethylene glycol methyl ether and isobornyl acetate.

Abstract: An extractive distillation process for separation ethers (in particular methyl t-butyl ether or ethyl t-butyl ether), aliphatic hydrocarbons (in particular isobutane and/or isobutene) and alcohols (in particular methanol or ethanol) employs as solvent sulfolane(s) and/or dialkyl sulfone(s), or N-(.beta.-mercaptoalkyl)-2-pyrrolidone(s), or a mixture of N-alkyl-2-pyrrolidone(s) and either sulfolane(s) or glycol compound(s).

Abstract: Acrylic acid cannot be completely separated from water by conventional distillation or rectification because of the minimum boiling azeotrope. Acrylic acid can be readily separated from water by extractive distillation. Effective agents are dimethylsulfoxide, sulfolane, dimethylformamide or dimethylacetamide.

Abstract: The separation of alkadienes from close-boiling alkenes by extractive distillation employs as solvent either N-(.beta.-mercaptoethyl)-2-pyrrolidone alone, or a mixture of N-(.beta.-mercaptoethyl)-2-pyrrolidone and either N-methyl-2-pyrrolidone or cyclohexanol, or a mixture of cyclohexanol and tetraethylene glycol. The separation of cycloalkadines from close-boiling alkadienes by extractive distillation employs N-(.beta.-mercaptoethyl)-2-pyrrolidone as solvent.

Abstract: Methylene chloride cannot be completely separated from methanol or ethanol by conventional distillation or rectification because of the mimimum boiling azeotrope. Methyelne chloride can be readily separated from methanol or ethanol by azeotropic or extractive distillation. Typical effective agents are: for methanol by azeotropic distillation, isopropanol or t-butanol; by extractive distillation, 1-nitropropane or n-butanol; for ethanol by extractive distillation, isobutanol or n-propyl acetate.

Abstract: 2-Methoxyethanol cannot be completely separated from water by conventional distillation or rectification because of the minimum boiling azeotrope. 2-Methoxyethanol can be readily separated from water by extractive distillation. Effective agents are dimethylsulfoxide, sulfolane, dimethylformamide or 1,4-butanediol.

Abstract: The separation of alkadienes from close-boiling alkenes by extractive distillation employes as solvent N-methyl-2-thiopyrrolidone, alone or in admixture with unsubstituted sulfolane (cyclotetramethylene sulfone), or a mixture of unsubstituted sulfone and N-methyl-2-pyrrolidone. The separation of cycloalkadienes from close-boiling alkadienes by extractive distillation employs N-methyl-2-thiopyrrolidone as solvent.

Abstract: The higher boiling ketone isomers are difficult to separate one from another by conventional distillation or rectification because of the close proximity of their boiling points. Ketone isomers can be readily separated from each other by extractive distillation. Typical examples of effective agents are: for 3-pentanone from 2-pentanone, dipropylene glycol; 3-hexanone from 2-hexanone, butoxypropanol; 3-heptanone from 2-heptanone, 50% ethylene glycol--50% butoxypropanol; 3-octanone from 2-octanone, ethylene glycol diacetate.

Abstract: An extractive distillation agent consisting essentially of ethylene carbonate, propylene carbonate or a mixture thereof is fed to an extractive distillation column used for the distillation of propylene oxide contaminated with water to obtain an overhead distillate fraction consisting of essentially anhydrous propylene oxide, and a heavier bottoms distillation fraction containing substantially all of the extraction distillation solvent and water introduced into the distillation column.

Abstract: Aromatic hydrocarbons containing 6-10 carbon atoms per molecule are separated from close-boiling olefinic hydrocarbons by extractive distillation employing as solvent either N-methyl-2-thiopyrrolidone alone, or a mixture of N-(.beta.-mercaptoethyl)-2-pyrrolidone and N-methyl-2-thiopyrrolidone, or a mixture of N-(.beta.-mercaptoethyl)-2-pyrrolidone and N-methyl-2-pyrrolidone.

Abstract: An organic solvent having a boiling point lower than that of water is removed from liquid containig water and the organic solvent contained in a tank by exhausting air in the tank, wherein an air pressure in the tank is kept about vapor pressure level of the liquid.

Abstract: A process for the manufacture of N-phenylmaleimide which comprises reacting maleic anhydride with aniline in a single step at elevated temperature in the presence of a water-immiscible organic solvent capable of forming an azeotrope with water and of p-toluenesulfonic acis as catalyst.

Abstract: Aromatic hydrocarbons containing 6-10 carbon atoms per molecule are separated from close-boiling olefinic hydrocarbons by extractive distillation employing N-(.beta.-hydroxyethyl)-2-pyrrolidone and/or cyclohexanol as solvent.

Abstract: Chloroform cannot be completely separated from methanol, ethanol or isopropanol by conventional distillation or rectification because of the minimum boiling azeotrope between chloroform and the alcohols. Chloroform can be readily separated from methanol, ethanol or isopropanol by extractive distillation. Typical effective agents are: for methanol, isopropanol or 4-methyl-2-pentanone; for ethanol, n-butanol or isobutyl acetate; for isopropanol, butyl acetate or ethylene glycol ethyl ether.

Abstract: Methylene chloride cannot be completely separated from ethyl vinyl ether by conventional distillation or rectification because of the minimum boiling azeotrope. Methylene chloride can be readily separated from ethyl vinyl ether by extractive distillation. Typical effective agents are ethylene glycol methyl ether acetate, 2-hexanone and 1-nitropropane.

Abstract: Trichloroethylene cannot be completely separated from n-butanol, isobutanol, 2-butanol or t-butanol by conventional distillation or rectification because of the minimum boiling azeotropes. Trichloroethylene can be readily separated from n-butanol, isobutanol, 2-butanol or t-butanol by extractive distillation. Typical effective agents are: for n-butanol, dimethylsulfoxide; for isobutanol, n-octanol; for 2-butanol, 2-methyl-1-pentanol and for t-butanol, n-butyl acetate.

Abstract: An extractive distillation agent consisting essentially of sulfolane is fed to an extractive distillation column used for the distillation of propylene oxide contaminated with water to obtain an overhead distillate fraction consisting of essentially anhydrous propylene oxide, and a heavier bottoms distillation fraction containing substantially all of the sulfolane and water introduced into the distillation column.

Abstract: An extractive distillation agent consisting essentially of 1-methyl-2-pyrrolidone is fed to an extractive distillation column used for the distillation of propylene oxide contaminated with water, acetone and methanol to obtain an overhead distillate fraction consisting of essentially anhydrous propylene oxide contaminated with reduced quantities of acetone and methanol, and a heavier bottoms distillation fraction containing substantially all of the 1-methyl-2-pyrrolidone, water and acetone and some of the methanol introduced into the distillation column.

Abstract: 1,1,1-Trichloroethane cannot be completely separated from n-hexane by conventional distillation or rectification because of the minimum boiling azeotrope. 1,1,1-Trichloroethane can be readily separated from n-hexane by extractive distillation. Typical effective agents are: methyl isoamyl ketone, amyl acetate and isobutanol.

Abstract: Pyridine cannot be completely separated from water by conventional distillation or rectification because of the minimum boiling azeotrope. Pyridine can be readily separated from water by using azeotropic or extractive distillation. Typical examples of effective agents are: by azeotropic distillation, methyl isoamyl ketone and propylene glycol dimethyl ether; by extractive distillation, isophorone and sulfolane.

Abstract: An extractive distillation process for separatin at least one C.sub.4 -C.sub.10 alkene (monoolefin) from at least one close-boiling alkane employs a solvent mixture of (a) at least one saturated alcohol (preferably cyclohexanol) and either (b1) at least one sulfolane (preferably cyclotetramethylene sulfone) or (b2) at least one glycol compound (preferably tetraethylene glycol) or (b1)+(b2).

Abstract: m-Xylene is difficult to separate from p-xylene or o-xylene by conventional distillation or rectification because of the close proximity of their boiling points. m-Xylene can be readily separated from p-xylene or o-xylene by using extractive distillation in which the agent is an alcohol. Typical examples of effective agents are: for m-xylene from o-xylene, 1-octanol and cyclododecanol; for p-xylene from m-xylene, diisobutyl carbinol and cyclododecanolphenethyl alcohol mixture.

Abstract: Ethyl ester cannot be completely separated from methylene chloride by conventional distillation or rectification because of the maximum boiling azeotrope. Ethyl ether can be readily separated from methylene chloride by extractive distillation. Typical effective agents are t-butyl alcohol, n-propyl acetate or propoxypropanol.

Abstract: Isopropanol and n-propanol cannot be completely separated from water by conventional distillation or rectification because of the minimum boiling azeotrope. Isopropanol and n-propanol can be readily separated from water by using azeotropic or extractive distillation. Typical examples of effective agents are: for isopropanol by azeotropic distillation, vinyl n-butyl ether; by extractive distillation, polyethylene glycol; for n-propanol by azeotropic distillation, amyl formate; by extractive distillation, n-butyl acetate.

Abstract: An extractive distillation process for separating at least one C.sub.4 -C.sub.10 alkene (monoolefin) from at least one close-boiling alkane (paraffin) employs as solvent a mixture of (a) at least one N-alkyl-2-pyrrolidone, preferably N-methyl-2-pyrrolidone and either (b1) at least one sulfolane compound (preferably cyclotetramethylene sulfone) or (b2) at least one glycol compound (preferably tetraethylene glycol) or both (b1) and (b2).

Abstract: In a method of optimizing the operation of a distillation column with a side heating device for reconditioning of extract which is received during the extraction of hydrocarbon-containing initial products with N-substituted morpholines whose substituents have not more than seven C-atoms as selective solvents a liquid is withdrawn to a side heating device through a chimney plate arranged above a feed plate, so that between 5 and 30 volume percent of the liquid supplied to the chimney plate is not withdrawn to the side heating device but instead supplied directly to a plate located underneath the chimney plate. A vapor-liquid mixture which has escaped through a top from the side heating device is returned back to the distillation column. The returned vapor-liquid mixture is fed either to the feed plate or to the plate located underneath the chimney plate. An arrangement for performing the inventive method is also provided.

Abstract: Cyclohexane cannot be readily separated from cyclohexene by conventional distillation or rectification because of the close proximity of their boiling points. Cyclohexane can be separated from cyclohexene by azeotropic or extractive distillation. Typical examples of effective agents are: for azeotropic; ethylene glycol methyl ether and n-butanol; for extractive; propylene glycol methyl ether and diacetone alcohol.

Abstract: An extractive distillation process for separating at least one aromatic hydrocarbon from at least one close-boiling alkane employs as solvent a mixture of (a) at least one N-mercaptoalkyl-2-pyrrolidone, preferably N-(.beta.-mercaptoethyl)-2-pyrrolidone and (b) at least one sulfolane, preferably cyclotetramethylene sulfone.

Abstract: An extractive distillation process for separating at least one C.sub.4 -C.sub.10 alkene (monoolefin) from at least one close-boiling alkane employs solvent at least one N-mercaptoalkyl-2-pyrrolidone, preferably N-(.beta.-mercaptoethyl)-2-pyrrolidone, optionally in admixture with at least one N-alkyl-2-pyrrolidone, preferably N-methyl-2-pyrrolidone.

Abstract: Cycloalkanes, preferably cyclohexane and/or cyclopentane, are separated from close-boiling alkanes by extractive distillation employing as solvent a mixture of (a) at least one N-hydroxyalkyl-2-pyrrolidone, preferably N-(.beta.-hydroxyethyl)-2-pyrrolidone, and (b) at least one saturated C.sub.5 -C.sub.9 alcohol, preferably cyclohexanol.

Abstract: Extractive distillation processes for separating aromatic hydrocarbon(s) or cycloalkane(s) or alkene(s) from close-boiling alkane(s) are carried out with a solvent including at least one N-alkyl-2-thiopyrrolidone compound, preferably N-methyl-2-thiopyrrolidone. Optionally, the solvent additionally contains a cosolvent, preferably tetraethylene glycol or N-(.beta.-mercaptoethyl)-2-pyrrolidone or unsubstituted sulfolane.

Abstract: A hydrocarbon material of the starting product is separated in an extractive distillation column in which an N-substituted morpholine whose substituents do not have more than seven carbon atoms is used as a selective solvent. The overhead product comes down as a top product of the extractive distillation and is fed through a coalescer in which the sump product comes down with a solvent content of 20 to 75% by weight at a temperature of 20.degree. to 70.degree. C. and subsequent to that is fed into a separating vessel. There it is separated into a heavier and lighter phase. After that the heavier phase is conducted into an extractive distillation column and the lighter phase into the overhead product distillation column.

Abstract: In the method for the production of an aromate concentrate suitable for use as blending component for gasifier fuel, feed hydrocarbon mixtures having boiling ranges substantially between 40.degree. and 170.degree. C., are subjected, without any previous separation into individual fractions, to an extractive distillation employing N-substituted morpholine, substituents of which display no more than seven C-atoms, as selective solvent. Herewith, the lower boiling non-aromates with a boiling range up to about 105.degree. C., practically completely, and most of the higher boiling non-aromates with a boiling range between about 105.degree. and 160.degree. C., are recovered as raffinate, whereas the aromates, which are to be employed in whole or in part as blending component, come down in the extract of the extractive distillation.

Abstract: The lower lactate esters are difficult to separate one from another by conventional distillation or rectification because of the close proximity of their boiling points. Lactate esters can be readily separated from each other by extractive distillation. Typical examples of effective agents are: for methyl lactate from ethyl lactate, ethylene glycol; ethyl lactate from isopropyl lactate, diethylene glycol; isopropyl lactate from n-propyl lactate, isophorone; n-propyl lactate from butyl lactate, 2-hydroxyacetophenone.

Abstract: Ethyl benzene cannot be easily removed from styrene by distillation because of the closeness of their boiling points. Ethyl benzene can be readily separated from styrene by means of extractive distillation using certain nitrogenous organic compounds. Typical effective agents are adiponitrile, methyl glutaronitrile and nitrobenzene.

Abstract: 3-Methyl-2-butanone cannot be separated from formic acid by distillation because of the presence of the maximum boiling azotrope. 3-Methol-2-butanoe can be readily removed from formic acid by extractive distillation using sulfolane. Typical effective agents are: sulfolane and ethylene glycol diacetate; sulfolane, m-toluic acid and anisole.

Abstract: An extractive distillation process for separating at least one cycloalkane or aromatic hydrocarbon from at least one close-boiling alkane employs as solvent at least one N-mercaptoalkyl-2-pyrrolidone, preferably N-(.beta.-mercaptoethyl)-2-pyrrolidone, either alone or in admixture with about 0.1-10 weight-% water.A liquid-liquid extraction process for separating at least one cycloalkane or aromatic hydrocarbon from at least one alkane employs as solvent at least one N-mercaptoalkyl-2-pyrrolidone, preferably N-(.beta.-mercaptoethyl)-2-pyrrolidone, either alone or in admixture with about 0.1-10 weight-% water.

Abstract: Cycloalkanes (preferably cyclopentane and/or cyclohexane) are separated from close-boiling alkanes by extractive distillation employing as solvent a mixture of (a) at least one N-mercaptoalkyl-2-pyrrolidone (preferably N-mercaptoethyl-2-pyrrolidone) and (b1) at least one N-alkyl-2-pyrrolidone (preferably N-methyl-2-pyrrolidone) and/or (b2) at least one saturated C.sub.5 -C.sub.9 alcohol (preferably cyclohexanol).

Abstract: A mixture of (a) at least one N-alkyl-2-pyrrolidone (preferably N-methyl-2-pyrrolidone) and (b) at least one glycol compound (preferably ethylene glycol or tetraethylene glycol) is used as solvent in the extractive distillation of a feed mixture of cycloalkane(s) (in particular cyclohexane) and close-boiling alkane(s).

Abstract: A mixture of (a) at least one N-alkyl-2-pyrrolidone (preferably N-methyl-2-pyrrolidone) and (b) at least one sulfolane (preferably unsubstituted sulfolane) is used as solvent in the extractive distillation of feed mixture of cycloalkane(s) (in particular cyclohexane) and close-boiling alkane(s).

Abstract: 4-Methyl-2-pentanone cannot be easily separated from formic acid or acetic acid by distillation because of the closeness of their boiling points. 4-Methyl-2-pentanone can be readily removed from formic acid or acetic acid by extractive distillation. Typical effective agents are sulfolane; sulfolane and heptanoic acid; sulfolane, azelaic acid and ethylene glycol diacetate.

Abstract: A mixture of (a) at least one saturated C5-C9 alcohol (preferably cyclohexanol) and (b) at least one sulfolane (preferably unsubstituted sulfolane, cyclotetramethylene sulfone) is used as solvent in the extractive distillation of a feed mixture of cycloalkane(s) in particular cyclohexane) and close-boiling alkane(s). A novel composition of matter contains (a) and (b), as defined above, and optionally also (c) water.