Abstract: A process for the continuous catalyst-free production of polyisocyanates by thermal decomposition of the N-substituted carbamic acid esters corresponding to the polyisocyanates, in which the carbamic acid esters to be decomposed, in the form of a 5 to 90% by weight solution in an inert high-boiling solvent, are heated to a temperature of 100.degree. to 400.degree. C. and are subsequently introduced with expansion as a sidestream into a distillation column (4), in the sump of which a pressure of 0.001 to 5 bar and a temperature of 150.degree. to 400.degree. C. are maintained so that the high boiler is kept boiling in the sump, and the decomposition products are simultaneously condensed continuously and selectively at the head of the distillation column. The high boiler, which optionally contains impurities, is continuously removed via the sump outlet in a quantity substantially corresponding to the quantity of high boiler introduced into the column as solvent for the carbamic acid ester.

Abstract: Heptane cannot be removed from heptane-vinyl acetate mixtures by distillation because of the minimum boiling azeotrope. Heptane can be readily removed from vinyl acetate by extractive distillation. Typical effective agents are dimethylsulfoxide, phenol, diisobutyl ketone and hexyl acetate.

Abstract: Octene-1 is difficult to separate from several of its isomers by conventional distillation or rectification because of the closeness of their boiling points. Octene-1 can be readily separated from its close boiling isomers by azeotropic or extractive distillation. Effective agents are: for azeotropic distillation, t-amyl methyl ether; for extractive distillation, isophorone.

Abstract: Heptane cannot be separated from vinyl acetate by conventional distillation or rectification because of the minimum boiling azeotrope. Heptane can be readily separated from vinyl acetate by using azeotropic distillation. Typical examples of effective agents are methyl acetate, ethanol, ethyl formate or t-amyl methyl ether.

Abstract: Hexane cannot be separated from vinyl acetate by conventional distillation or rectification because of the minimum boiling azeotrope. Hexane can be readily separated from vinyl acetate by using azeotropic distillation. Typical examples of effective agents are acetone, acetonitrile or methyl t-butyl ether.

Abstract: For the separation of butanes and butenes by extractive distillation, a charge mainly containing butanes and butenes is contacted in an extractive distillation column under pressure with a polar solvent (e.g., dimethyl formamide), the butanes being collected at the head. The solvent containing the butenes passes into a second column under pressure, where the butenes are partly desorbed and collected at the head. The solvent still containing butenes is purified in a third column under atmospheric pressure and the solvent-containing vapor distillate thereof is returned, after compression, to the lower part of the second column.

Abstract: The separation of vinyl acetate from methyl acrylate by distillation is difficult because of the closeness of their boiling points. Vinyl acetate can be readily removed from methyl acrylate by extractive distillation. Typical effective agents are phenol, methoxyethanol and isobutyl vinyl ether.

Abstract: 4-Methyl-2-pentanone cannot be easily separated from formic acid by distillation because of the closeness of their boiling points. 4-Methyl-2-pentanone can be readily removed from formic acid by extractive distillation. Typical effective agents are dimethylsulfoxide (DMSO) and 2-undecanone; DMSO and octanoic acid; DMSO and hexyl acetate.

Abstract: A method for the separation of Isoflurane from its admixture with other compounds produced in the chlorination of 2-difluoromethoxy-1,1,1-trifluoroethane including subjecting the mixture to distillation, distilling off the Isoflurane and effecting said distillation as an extractive distillation employing an extractive solvent which retards the vapor pressure of Isoflurane.

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: 3-Pentanone cannot be completely removed from 3-pentanone and formic acid mixtures by distillation because of the presence of the maximum azeotrope. 3-Pentanone can be readily removed from 3-pentanone-formic acid mixtures by extractive distillation in which the extractive agent is cyclopentanone, either alone or admixed with certain high boiling organic compounds. Examples of effective agents are cyclopentanone; cyclopentanone and 2-methoxyethyl ether; cyclopentanone, adiponitrile and octanoic acid.

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: 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: Glycerine cannot be easily separated from mannitol, lactose or lactitol by atmospheric or reduced pressure distillation because of their high boiling points. Glycerine can be readily separated from mannitol, lactose or lactitol by azeotropic distillation. Typical effective agents are biphenyl, benzyl benzoate and dimethyl phthalate.

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 for recovering volatile, organic compounds from manure, by:i) acidifying and concentrating the manure;ii) condensing the formed vapor; andiii) separating the volatile, organic compounds from the condensate.Preferably the volatile, organic compounds are removed from the condensate by liquid extraction, crystallization, distillation and/or ion exchange.

Abstract: 4-Methyl-2-pentanone cannot be easily separated from acetic acid by distillation because of the closeness of their boiling points. 4-Methyl-2-pentanone can be readily removed from acetic acid by extractive distillation. Typical effective agents are dimethlsulfoxide (DMSO); DMSO and adipic acid; DMSO, adipic acid and adiponitrile.

Abstract: Glycerine cannot be easily separated from sorbitol by atmospheric or reduced pressure distillation because of their high boiling points. Glycerine can be readily separated from sorbitol by azeotropic distillation. Typical effective agents are biphenyl, benzyl benzoate and dimethyl phthalate.

Abstract: 3-Methyl-2-butanone cannot be separated from formic acid by distillation because of the presence of the maximum boiling azeotrope. 3-Methyl-2-butanone can be readily removed from formic acid by extractive distillation using dimethylsulfoxide (DMSO). Typical effective agents are: DMSO and heptanoic acid; DMSO, octanoic acid and butyl benzoate.

Abstract: Formic acid cannot be completely removed from formic acid--water mixtures by distillation because of the presence of the maximum azeotrope. Formic acid can be readily removed from mixtures containing it and water by using extractive distillation in which the extractive distillation agent is cyclohexanone, isophorone or a mixture of these with certain organic compounds. Typical examples of effective agents are cyclohexanone; isophorone; cyclohexanone and neodecanoic acid; isophorone and diisobutyl ketone.

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: Acetic acid is difficult to separate from water by conventional distillation or rectification because of the close proximity of their boiling points. Acetic acid can be readily separated from water by using azeotropic distillation. Typical examples of effective agents are ethyl n-valerate and 4-methyl-2-pentanone.

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: A process for separating m- and p-dichlorobenzene by extractive rectification with an extractant and removal of this extractant. Using as extractant an alkylene carbonate of the formula ##STR1## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are identical to or different from one another and each is hydrogen, methyl or ethyl, with the proviso that together the radicals R.sup.1 to R.sup.4 do not contain more than 6 carbon atoms.The process of the invention makes it possible to separate off the m-isomer in high purity.

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 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 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: The present invention is directed to an improved reverse osmosis membrane that shows surprisingly improved solute rejection and permeation properties. The membrane includes a separating layer of a polyamideurethane formed in situ by reaction of a haloformyloxy-substituted acyl halide with a diamine-treated substrate.

Abstract: Ethylbenzene is separated from xylene(s) by extractive distillation employing at least one copper(I) salt of a hydrocarbonsulfonic acid as extractant(s).

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 2-hydroxyethyl 2-hydroxyethylcarbamate, and 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 2-hydroxyethyl 2-hydroxyethycarbamate, and water introduced into the disillation 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: p-Cymene and p-menthane are difficult to separate one from another by conventional distillation or rectification because of the close proximity of their boiling points. p-Cymene and p-menthane can be readily separated one from another by using azeotropic or extractive distillation. Typical examples of effective agents, for azeotropic distillation: diethyelene glycol ethyl ether, 1-pentanol and isobutanol; for extractive distillation: butyl benzoate, undecyl alcohol and methyl benzoate.

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: m-Xylene is difficult to separate from o-xylene by conventional distillation or rectification because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the agent is an aliphatic ester. Typical examples of effective agents are diethyl maleate, diethyl malonate or 2-ethyl hexyl acetate.

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: Methylene chloride cannot be completely separated from methyl formate or ethyl formate by conventional distillation or rectification because of the minimum boiling azeotrope. Methylene chloride can be readily separated from methyl formate or ethyl formate by extractive distillation. Typical effective agents are: for methyl formate, n-butyl acetate and 3-hexanone; for ethyl formate, isobornyl acetate and 2-heptanone.

Abstract: 4-Methyl-2-pentanone cannot be easily separated from acetic acid by distillation because of the closeness of their boiling points. 4-Methyl-2-phentanone can be readily removed from acetic acid by extractive distillation. Typical effective agents are dimethylformamide (DMFA); DMFA and m-toluic acid; DMFA, p-toluic acid and isobutyl heptyl ketone.

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: p-Xylene is difficult to separate from m-xylene by conventional distillation or rectification because of the close proximity of their boiling points. p-Xylene can be readily separated from m-xylene by using extractive distillation in which the agent is an ester. Typical examples of effective agents are butyl butyrate, methyl caproate and methyl heptanoate.

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: t-Butyl alcohol cannot be completely separated from water by conventional distillation or rectification because of the minimum boiling azeotrope. t-Butyl alcohol can be readily separated from water by using azeotropic or extractive distillation. Typical examples of effective agents are: by azeotropic distillation, vinyl n-butyl ether and propylene glycol dimethyl ether; by extractive distillation, 1,3-butanediol and triethylene glycol.

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: Methylal cannot be completely separated from methylene chloride by conventional distallation or rectification because of the maximum boiling azeotrope. Methylal can be readily separated from methylene chloride by extractive distillation. Typical effective agents are n-butyl acetate, diisobutyl ether and 4-methyl-2-pentanone.

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 azeotropic distillation in which the agent is an aliphatic ester. Typical examples of effective agents are: for m-xylene from p-xylene, propyl butyrate or methyl valerate; for m-xylene from o-xylene, hexyl formate or methyl valerate.

Abstract: m-Xylene is difficult to separate from o-xylene by conventional distillation or rectification because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is a higher boiling ester. Typical examples of effective agents are diisononyl adipate, glycerol triacetate and dimethyl phthalate.