Abstract: Ethanol, isopropanol and water cannot be separated from each other by distillation or rectification because of minimum azeotropes. They are readily separated by extractive distillation. Effective agents are: dimethylsulfoxide for ethanol, phenol for isopropanol.

Abstract: 2-Butanol cannot be separated from isobutanol by distillation or rectification because of the closeness of their boiling points. 2-Butanol is readily separated from isobutanol by extractive distillation. Effective agents are propylene glycol propyl ether, 2-methoxyethanol and ethyl acetate.

Abstract: 2-Methyl-1-butanol and 3-methyl-1-butanol are difficult to separate from 1-pentanol by conventional distillation or rectification because of the proximity of their boiling points. 2-Methyl-1-butanol and 3-methyl-1-butanol can be easily separated from 1-pentanol by azeotropic distillation. Effective agents are toluene, methyl acetate and tetrahydrofuran.

Abstract: 4-Methyl-2-pentanol cannot be separated from 3-methyl-1-butanol by distillation because of the closeness of their boiling points. 4-Methyl-2-pentanol can be easily separated from 3-methyl-1-butanol by azeotropic distillation. Effective agents are m-xylene and cumene.

Abstract: 1-Propanol cannot be separated from t-amyl alcohol by distillation or rectification because of the closeness of their boiling points. 1-Propanol is readily separated from t-amyl alcohol by azeotropic distillation. Effective agents are heptane, ethyl acetate and tetrahydrofuran.

Abstract: 1-Propanol and t-amyl alcohol cannot be separated by distillation or rectification because of the closeness of their boiling points. 1-Propanol is readily separated from t-amyl alcohol by extractive distillation. Effective agents are dipentene, amyl acetate and 1,4-dioxane.

Abstract: Close boiling hydrocarbon impurities are separated from acetone by extractive distillation using a C.sub.9 -C.sub.14 alkane and/or a C.sub.8 -C.sub.12 aromatic hydrocarbon extractive distillation solvent.

Abstract: 2-Methyl-1-propanol is difficult to separate from 2-methyl-1-butanol by conventional distillation or rectification because of the proximity of their boiling points. 2-Methyl-1-propanol can be readily separated from 2-methyl-1-butanol by extractive distillation. Effective agents are hexyl formate, 2-heptanone and dipropyl amine.

Abstract: 2-Methyl-1-propanol is difficult to separate from 1-butanol by conventional distillation or rectification because of the proximity of their boiling points. 2-Methyl-1-propanol can be readily separated from 1-butanol by extractive distillation. Effective agents are ethyl benzene, amyl acetate and propoxypropanol.

Abstract: 2-Methyl-1-propanol is difficult to separate from 2-butanol by conventional distillation or rectification because of the proximity of their boiling points. 2-Methyl-1-propanol can be readily separated from 2-butanol by extractive distillation. Effective agents are hexyl acetate, dimethyl phthalate and p-xylene.

Abstract: T-Amyl alcohol and 2-methyl-1-propanol are difficult to separate by conventional distillation or rectification because of the proximity of their boiling points. T-Amyl alcohol can be easily separated from 2-methyl-1-propanol by extractive distillation. Effective agents are N,N-dimethylacetamide, cyclohexyl amine and glycerol.

Abstract: 2-Methyl-1-propanol is difficult to separate from 1-butanol by conventional distillation or rectification because of the proximity of their boiling points. 2-Methyl-1-propanol can be easily separated from 1-butanol by azeotropic distillation. Effective agents are isobutyl acetate, methyl cyclohexane and 2-nitropropane.

Abstract: The invention relates to an improved distillation method wherein hexamethylcyclotrisiloxane is isolated from a crude blend thereof by mixing the crude blend with a hydrocarbon co-solvent having a normal boiling point of 125.degree. C. to 150.degree. C. and distilling the resulting mixture in an apparatus having a reboiler, a fractionating column and a condenser, whereby deposition of solid hexamethylcyclotrisiloxane in the condenser is eliminated.

Abstract: 2-Methyl-1-butanol is impossible to separate from 3-methyl-l-butanol because they both boil at 130.degree. C. 2-Methyl-1-butanol can be readily separated from 3-methyl-1-butanol by extractive distillation. Effective agents are o-xylene, 3-carene and 1-methoxy-2-propanol.

Abstract: A polymerization inhibitor composition for inhibiting the polymerization of aromatic vinyl monomers at elevated temperatures comprising:(a) a benzofuroxan derivative of the formula ##STR1## wherein R is C.sub.1 -C.sub.4 alkyl or alkoxy; R.sup.1 is a nitro group; and m and n are each independently 0, 1, or 2; and(b) a solvent selected from the group consisting of toluene, xylene, ethylbenzene, vinyltoluene, divinylbenzene, alpha-methylstyrene, and a C.sub.12 -C.sub.18 hydrocarbon,and methods for inhibiting the polymerization of aromatic vinyl monomers at elevated temperatures using this composition.

Abstract: The polymerization of a vinyl aromatic monomer such as styrene is inhibited by the addition of a composition of a benzoquinone derivative and a hydroxylamine compound.

Abstract: 2-Methyl-1-propanol is difficult to separate from 2-methyl-1-butanol by conventional distillation or rectification because of the proximity of their boiling points. 2-Methyl-1-propanol can be readily separated from 2-methyl-1-butanol by azeotropic distillation. Effective agents are tetrahydrofuran, methyl acetate and toluene.

Abstract: 3-Carene and limonene cannot be separated from each other by rectification because of the closeness of their boiling points. They are readily separated by extractive distillation. Effective agents are: diethylene glycol phenyl ether, nonyl phenol, tripropylene glycol methyl ether, ethyl salicylate, 4-ethylphenol and 2-phenoxyethanol.

Abstract: For the regeneration of a liquid desiccant, a stripping agent is used which is liquid at ambient temperature and pressure, and forms a heteroazeotrope with water, along with the following steps: (a) distillation of the water-laden liquid desiccant to form vapor and partially regenerated liquid desiccant; (b) reboil partially regenerated liquid desiccant; (c) stripping of partially regenerated liquid desiccant during (a) and (b), using vaporized stripping agent; (d) a condensing of vapor the exiting the distillation, the condensation producing two liquid phases, one mainly water and the other mainly stripping agent; (e) heating the stripping agent-rich liquid phase exiting step (d) to generate a vapor phase which is richer in water than said liquid phase and a water-depleted liquid phase; and (f) returning the vaporized liquid phase exiting step (e) to step (c).

Abstract: Ethanol is impossible to separate from 2-butanone by conventional distillation or rectification because of the minimum boiling azeotrope between these two. Ethanol can be readily separated from 2-butanone by extractive distillation. Effective agents are dipromyl amine, phenol and dimethylsulfoxide.

Abstract: 3-Methyl-2-butanol, 2-pentanol and 1-butanol are difficult to separate by conventional distillation or rectification because of the proximity of their boiling points. Mixtures of these three can be readily separated from each other by azeotropic distillation. Effective agents are hexyl acetate, hexane and 3-methyl pentane.

Abstract: Ethanol is difficult to separate from isopropanol by conventional distillation or rectification because of the proximity of their boiling points. Ethanol can be readily separated from isopropanol by extractive distillation. Effective agents are dipentene, anisole and ethyl benzene.

Abstract: Ethanol is difficult to separate from isopropanol by conventional distillation or rectification because of the proximity of their boiling points. Ethanol can be readily separated from isopropanol by azeotropic distillation. Effective agents are sec. butyl acetate, hexene-1 and 1,3-dioxolane.

Abstract: Propylene glycol is difficult to separate from ethylene glycol by conventional distillation or rectification because of the proximity of their boiling points. Propylene glycol can be readily separated from ethlene glycol by azeotropic distillation. Effective agens are m-diisopropyl benzene, 1-octene, 3-carene and myrcene.

Abstract: Propylene glycol is difficult to separate from 1,2-butanediol by conventional distillation or rectification because of the proximity of their boling points. Propylene glycol can be readily separated from 1,2-butanediol by azeotropic distillation. Effective agents are 2,2-dimethyl butane, 3-carene and diethyl benzene.

Abstract: Glycerine is difficult to separate from bis(hydroxymethyl)tetrahydrofuran by conventional distillation or rectification because of the proximity of their boiling points. Glycerine can be readily separated from bis(hydroxymethyl)tetrahydrofuran by azeotropic distillation. Effective agents are m-xylene, beta-pinene and dicyclopentadiene.

Abstract: 1-Butanol is difficult to semarate from 2-pentanol by conventional distillation or rectification because of the proximity of their boiling points. 1-Butanol can be readily separated from 2-pentanol by azeotropic distillation. Effective agents are 1-octene, hexane and methyl cyclohexane.

Abstract: 3-Methyl-2-butanol is difficult to separate from 1-butanol by conventional distillation or rectification because of the proximity of their boiling points. 3-Methyl-2-butanol can be readily separated from 1-butanol by extractive distillation. Effective agents are ethyl n-valerate, dimethylacetamide and dimethylsulfoxide.

Abstract: 1-Butanol is difficult to separate from 2-pentanol by conventional distillation or rectification because of the proximity of their boiling points. 1-Butanol can be readily separated from 2-pentanol by extractive distillation. Effective agents are ethyl benzene, d-limonene and terpinolene.

Abstract: Benzene and other aromatics are separated from a stream of mixed hydrocarbons containing both aromatics and non-aromatics by extractive distillation with a solvent system containing dimethyl sulfoxide and optionally a co-solvent, preferably water, followed by distillation stripping of the aromatics from the enriched solvent system, and recycle of the lean solvent system to the extractive distillation step.

Abstract: The present invention relates to a process for the preparation of tetrafluorophthalic acid and/or tetrafluorophthalic anhydride by reacting a compound of the formula ##STR1## in which X is a radical ##STR2## which is optionally mono- or polysubstituted on the aromatic nucleus by fluorine and/or chlorine and/or alkyl groups having 1 to 4 carbon atoms, or is a radical ##STR3## in which R.sub.1, R.sub.2 and R.sub.3 are as defined, with water, and subsequently removing the water still present by azeotropic distillation or extracting the tetrafluorophthalic acid and/or its anhydride with a water-insoluble solvent or solvent mixture.

Abstract: For the separation of butenes and butanes by extractive distillation, a charge mainly containing butenes and butanes is contacted in an extractive distillation column under pressure with a first selective polar solvent, S1 (e.g., dimethyl formamide), the butanes being collected at the top. The solvent S1 containing the butenes and passing out at the bottom is mixed with a second solvent, S2, having a boiling point intermediate between that of butenes and that of the solvent S1, the mixture passing into a desorption column under pressure, where the butenes are collected at the top. The mixture of solvent S1 and S2 is separated in a purification column under atmospheric pressure, the solvent S2 passing out at the top is recycled to the desorption column, and the solvent S1 passing out at the bottom is recycled to the extractive distillation column.

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: An improved process for preparing and purifying glycol ether esters is disclosed. An azeotroping agent is included at a sufficiently low level to allow removal of the water of reaction, but also permit removal of by-products from esterification in the low-boiling component.

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: 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: A process for the dehydration of substances, mixtures, primarily condensation reaction mixtures, (e.g. direct esterification, direct acetal formation, direct ketal formation), performed by continuous azeotropic distillation with an organic solvent forming with water an azeotropic mixture of minimal boiling point and unable to mix with water, carried out in such a way that the distillate is cooled at least to the temperature, at which the condensate with the given water content or the organic phase of the condensate is just supersaturated with respect to water, and the organic phase of lower water content obtained in this way is recycled to the distilling boiler. The organic solvents used are e.g. benzene, toluene, 1,2-dichloroethane, chloroform, carbon tetrachloride.

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: 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: 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: A process for producing cis-2-methyl-2-butenoic acid, which process is preferably based on technical 2-methyl-2-butene nitrile and leads to pure products preferably without costly rectification. The technical nitrile is hydrolyzed by concentrated sulfuric acid at temperatures of up to 130.degree. C. and, following dilution of the sulfuric acid to about 50%, at temperatures of up to 130.degree. C. It is treated by distilling and fractional crystallization.

Abstract: The present invention provides a process to recover esters of mercapto acids from solutions containing water by mixing an extraction mixture comprising cycloalkane, arene, and an aqueous inorganic salt solution with an ester of mercapto acid and water solution followed by separating and distilling the resultant organic phase to recover the ester of mercapto acid.

Abstract: Triethylene glycol cannot be easily separated from glycerine or 1,2,4-butanetriol by atmospheric or reduced pressure distillation because of the closeness of their boiling points. Triethylene glycol can be readily separated from glycerine or 1,2,4-butanetriol by azeotropic distillation. Effective agents are p-xylene, alphapinene and diisobutyl ketone.

Abstract: Glycerine cannot be easily separated from triethylene glycol and 1,2,4-butanetriol by atmospheric or reduced pressure distillation because of the closeness of their boiling points. Glycerine can be readily separated from triethylene glycol and 1,2,4-butanetriol by azeotropic distillation. Typical effective agents are m-xylene, dipentene and 2-methoxyethyl ether.

Abstract: Ethylene glycol cannot be easily separated from 1,2-butanediol or 1,3-butanediol by atmospheric or reduced pressure distillation because of the closeness of their boiling points. Ethylene glycol can be readily separated from the butanediols by azeotropic distillation. Typical effective agents are ethyl benzene, 3-heptanone or diisobutyl ketone.

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: 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.

Abstract: Water-insoluble crystallizable epoxy alcohols such as phenyl glycidol are recovered from epoxidation reaction mixtures by washing the mixture with water, concentrating the mixture by distillation under vacuum to remove unreacted hydroperoxide and alcohol co-product, and crystallizing the epoxy alcohol from solution. Minimal decomposition of the epoxy alcohol is observed.

Abstract: A complex mixture of polyols cannot be easily separated by atmospheric or reduced pressure distillation because of the closeness of their boiling points. A mixture of polyols can be readily separated by azeotropic distillation. Typical effective agents are: p-xylene for propylene glycol from 2,3-butanediol and 1,2-butanediol; diisobutyl ketone for ethylene glycol from 1,2-butanediol and 1,3-butanediol; dipentene for glycerine from triethylene glycol and 1,2,4-butanetriol; propylene glycol isobutyl ether for 2,3-butanediol from propylene glycol.

Abstract: Acetone cannot be easily separated from benzene in high purity by distillation because of the closeness of their vapor pressures. Acetone can be readily removed from benzene by azeotropic distillation using certain aromatic hydrocarbons. Typical effective azeotropic distillation agents are: toluene, ethyl benzene and mesitylene.