Abstract: Process for distillatively separating a mixture containing a vinyl ether of the general formula (I) R1—O—CH?CH2??(I) and alcohol of the general formula (II) R2—OH??(II) in which R1 and R2 are each independently a saturated or unsaturated, aliphatic or cycloaliphatic radical having from 2 to 10 carbon atoms, and in which the alcohol (II) has a boiling point which is at least 1° C. higher, measured at or extrapolated to 0.1 MPa abs, than the vinyl ether (I), by a) passing the mixture into a first distillation column and withdrawing, as a top product, an azeotrope containing vinyl ether (I) and alcohol (II) and, as a bottom product, a stream enriched with the alcohol (II); b) passing the azeotrope containing vinyl ether (I) and alcohol (II) from the first distillation column into a second distillation column which is operated at a pressure which is from 0.

Abstract: The invention relates to a process for reducing the aldehyde concentration in a mixture comprising cyclohexanone and one or more aldehydes, said process comprising distilling said mixture in a distillation column in the presence of an alkaline compound, wherein in the bottom of the distillation column substantially no water is present.

Abstract: ?9 THC acid is obtained from plant material and extracted into an aqueous solvent under conditions of pH control. The acid is converted to a salt and the salt extracted into a polar solvent, yielding acid of high purity. The ?9 THC acid is then converted to ?9 THC which is further purified and combined with a carrier for pharmaceutical use.

Abstract: The invention relates to an energy efficient process for the distillative working-up of aqueous amine solutions that occur in the catalytic hydrogenation of nitroaromatic compounds. In this process, the amine is freed from water and also the water is obtained free from amine and low-boiling compounds and the concentrated low-boiling compounds are obtained.

Abstract: A process is described for the recovery of substantially pure ethyl acetate from a feedstock including ethyl acetate, ethanol and water. The process includes supplying the feedstock to a first distillation zone maintained under first distillation conditions effective for distilling from the feedstock a first distillate including ethyl acetate, ethanol, and less than about 10 mol % water. The first distillate is recovered from the first distillation zone and is supplied to a second distillation zone maintained under second distillation conditions, which include use of a higher pressure than that of the first distillation zone. The second distillation conditions are effective for distilling from the first distillate a second distillate including ethanol, water, and a minor proportion of ethyl acetate and yielding a substantially pure ethyl acetate bottom product, which is recovered. The second distillate is returned to the first distillation zone.

Abstract: The invention relates to a process for preparing isocyanates by reaction of amines with phosgene in the presence of inert organic solvents in a reactor and subsequent work-up of the reaction mixture leaving the reactor, wherein the solvent is separated off in a two-stage or multistage, preferably two-stage, distillation process in which the solvent is separated off at a pressure of 0.1-15 bar in a first apparatus and at 1-900 mbar in a second apparatus or further apparatuses, with the heat of condensation of the solvent vapor from the first apparatus being used for partial or complete vaporization of solvent in the second apparatus.

Abstract: The present invention relates to a system and a process for obtaining phenanthrene of about 95% purity from coal tar distilled fraction containing crude phenanthrene by performing fractional distillation at a reduced pressure of 50 mm mercury and at a temperature range of 160-180° C. to obtain first distilled fraction containing acenaphthene and fluorene; a second distillate fraction at a temperature range of 200-230° C. containing phenanthrene, anthracene and traces of carbazole; followed by re-distilling the second distillate fraction at a temperature range of 210-224° C. to finally obtain pure phenanthrene and a residue which is again used for the recovery of residual phenanthrene by re-distillation at a temperature range of 210-224° C.

Abstract: In a membrane distillation process in which a liquid to be concentrated is separated from a vapour space (11) by a vapour-permeable liquid- or water-tight membrane or membrane wall (13), to set the absolute pressure of the liquid to be concentrated a reduced pressure is imparted to this which lowers the absolute pressure of the liquid to be concentrated. A corresponding membrane distillation device is also specified.

Abstract: The invention relates to the field of separation by distillation of 6-aminocapronitrile (ACN) and hexamethylenediamine (HMD) from a mixture containing ACN, HMD, tetrahydrozaepine (THA), adiponitrile (ADN) and low boilers (LB). A method for producing a distillate stream comprising HMD is disclosed, which is suitable for the production of Nylon-6,6. The tails stream from the distillation of the mixture can be further distilled to produce a distillate containing ACN and THA, which is particularly suitable for use in the production of caprolactam and Nylon-6 from the caprolactam. Process conditions of the method of the invention disfavor the production of 2-cyanocyclopentylideneirnine (CPI).

Abstract: The present invention relates to a new process for obtaining fatty acids with improved color, odor and heat stability which is characterized in that: (a) in a first step the crude acids are fed to a rectification (“precut”) column in order to remove low boiling by-products being present in the starting material as a top fraction, and (b) in a second step the bottom fraction of the precut column is fed to a sidestream column in order to obtain the pure fatty acids as the side fraction, to remove low boiling by-products which have been formed in the course of the first distillation as a top fraction and to remove high boiling by-products, either being present from the starting material or formed during the first distillation, with the residue.

Abstract: A method, system, and apparatuses for simultaneous heat and mass transfer utilizing a carrier-gas at various absolute pressures are described. A method may include: thermally coupling at least two continuous contacting apparatuses together; varying the pressure between the at least two continuous contacting apparatuses; allowing heat removed from the first continuous contacting apparatus to be the heat delivered to the second continuous contacting apparatus. A system may include: at least two continuous contacting apparatuses thermally coupled together and operating at different absolute pressures. A continuous contacting apparatus may include: an evaporation chamber and a dew-formation chamber both operating at an absolute pressure in a vacuum range. A continuous contacting vapor recompression apparatus may include: an evaporation chamber operating at a first absolute pressure; and a dew-formation chamber operating at a second absolute pressure higher than the first absolute pressure.

Abstract: The present invention provides a continuous process for recovering acetone from a waste stream from an acetone purification stage. The waste stream contains mesityl oxide and optionally acetone. The process for recovering acetone includes separating the waste stream in a separating device at least in one stream containing mesityl oxide and optionally a further stream containing acetone, then concentrating mesityl oxide in the mesityl oxide containing stream, and finally recycling the concentrated mesityl oxide stream to the separating device and bringing it into contact with a basic or acidic aqueous medium or with an acidic catalyst in the presence of water whereby mesityl oxide is at least partially hydrolyzed to acetone.

Abstract: The present invention provides a method and a system for stripping volatile compounds such as ammonia from liquids. Part of the ammonia is stripped from the liquid in a system having a shunt through which liquid such as e.g. fermented biomass can be diverted in the form of a side stream in liquid contact with a main fermentor(s). The stripper system is connected to an evaporator. In the evaporator aqueous liquid is heated at a pressure below atmospheric pressure whereby vapor is developed at a temperature below 100° C. The vapor from the evaporator is directed to the liquid medium containing ammonia and this results in ammonia being stripped from the liquid and transferred to the vapor phase. The vapor phase is condensed in a first condenser at a low pressure, and the liquid thus obtained is further treated in a stripper unit at a higher pressure.

Abstract: A method for the preparation of pulp by means of alkaline cooking, in which method spent liquor is transferred to pressurized tanks, and at least one liquor is expanded corresponding to a temperature difference of 1 to 5° C. The generated steam is led to turpentine recovery. Thus, the removal of turpentine and gases dissolved in said liquor is effective, the amount of recovered turpentine increases, and pulp of better washability and higher quality is obtained.

Abstract: The invention relates to azeotropic and azeotrope-like mixtures of 1,1,1,3,3-pentafluorobutane (HFC-365) and hydrogen fluoride and a process for separating the azeotrope-like mixtures. The compositions of the invention are useful as an intermediate in the production of HFC-365. The latter is useful as a nontoxic, zero ozone depleting fluorocarbon useful as a solvent, blowing agent, refrigerant, cleaning agent and aerosol to propellant.

Abstract: A process for working up by distillation the crude products obtained in the process according to DE-A 196 07 954 and containing 1,6-hexanediol (HDO), 1,5-pentanediol (PDO) or caprolactone (CLO) in order to obtain the corresponding pure products, the working-up by distillation being carried out in each case in a dividing wall column (TK) in which a dividing wall (T) is arranged in the longitudinal direction of the column with formation of an upper common column region (1), a lower common column region (6), a feed section (2, 4) having a rectification section (2) and stripping section (4), and a take-off section (3, 5) having a stripping section (3) and rectification section (5), with feeding of the respective crude product HDO, PLO or CLO in the middle region of the feed section (2, 4) and removal of the high boiler fraction (C) from the bottom of the column, of the low boiler fraction (A) via the top of the column and of the medium boiler fraction (B) from the middle region of the take-off section (3, 5), or

Abstract: A liquid phase process is disclosed for producing halogenated alkane adducts of the formula CAR1R2CBR3R4 (where A, B, R1, R2, R3, and R4 are as defined in the specification) which involves contacting a corresponding halogenated alkane, AB, with a corresponding olefin, CR1R2?CR3R4 in a dinitrile or cyclic carbonate ester solvent which divides the reaction mixture into two liquid phases and in the presence of a catalyst system containing (i) at least one catalyst selected from monovalent and divalent copper; and optionally (ii) a promoter selected from aromatic or aliphatic heterocyclic compounds which contain at least one carbon-nitrogen double bond in the heterocyclic ring. When hydrochlorofluorocarbons are formed, the chlorine content may be reduced by reacting the hydrochlorofluorocarbons with HF. New compounds disclosed include CF3CF2CCl2CH2CCl3, CF3CCl2CH2CH2Cl and CF3CCl2CH2CHClF. These compounds are useful as intermediates for producing hydrofluorocarbons.

Abstract: N-(2-hydroxyethyl)-2-pyrrolidone (HEP) is purified by a distillation sequence in which the purified HEP is recovered as a side stream without being separated as an overhead at any point in the procedure.

Abstract: A process is proposed for the separation of C5+ cuts by distillation into a low-boiler (A), a medium-boiler (B) and a high-boiler fraction (C) in one or more dividing-wall columns (TK), in which a dividing wall (T) is arranged in the longitudinal direction of the column with formation of an upper, common column region (1), a lower, common column region (6), a feed part (2, 4) with rectifying section (2) and stripping section (4), and a withdrawal part (3, 5) with rectifying section (5) and stripping section (3), with feed of the C5+ cut (A, B, C) into the central region of the feed part (2, 4), discharge of the high-boiler fraction (C) from the bottom of the column, discharge of the low-boiler fraction (A) via the top of the column, and discharge of the medium-boiler fraction (B) from the central region of the withdrawal part (3, 5), wherein the dividing ratio of the liquid reflux at the upper end of the dividing wall (T) is set in such a way that the proportion of high-boiling key components in the liquid re

Abstract: A process for recovering methanol from mixtures containing methanol and water, comprising multistage evaporation with heat integration, wherein the pressure is reduced from each stage to the next, and a downstream series of distillation stages with heat integration, wherein the pressure is increased from each stage to the next. The process reduces the amount of energy required for methanol recovery.

Abstract: The invention relates to a method for separating by distillation a portion or the entirety of an azeptine derivative (III), which is selected from the group consisting of aminohexylidene imine, tetrahydroazepine, hexylhexahydroazepine and of aminohexylhexahydroazepine, out of a mixture (II) containing an azepine derivative (III) and an amine (I). The inventive method is characterized in that the distillation is carried out with a maximum bottom temperature of 150° C.

Abstract: A process for the high yield production of high purity glacial methacrylic acid (“HPMAA”) with minimization of decomposition of hydroxy isobutyric acid (HIBA). The HPMAA is substantially pure, specifically 99% pure or greater with a water content of 0.05% or less. This improved process involves the steps of providing a crude MAA stream which was formed by hydrolyzing acetone cyanohydrin and, therefore, includes HIBA which is an intermediate product of the hydrolysis reaction, and purifying that crude methacrylic acid stream in a series of successive distillation steps.

Abstract: The present invention relates to a process for separating 2-butanol from tert-butanol/water by adding of tert-butanol such that the water concentration lowers to less than the limit concentration of the distillation boundary line connecting the two azeotropes TBA/water and SBA/water and is subsequently worked up by distillation.

Abstract: The invention relates to a process for separating 2-butanol from an industrial mixture which includes 2-butanol, tert-butanol and water by separating water from the industrial mixture by distillation to obtain a distillate, wherein the distillate has, in terms of the 2-butanol, tert-butanol and water in the industrial mixture, a proportion by mass of water, which at a pressure, is greater than the limit concentration of the distillation boundary line connecting an azeotrope of tert-butanol and water; and an azeotrope of 2-butanol and water; subsequently changing the pressure so that the mixture has, in terms of the 2-butanol, tert-butanol and water in the distillate, a proportion by mass of water which is less than the limit concentration of the distillation boundary line connecting the distillation boundary line connecting an azeotrope of tert-butanol and water; and an azeotrope of 2-butanol and water; and subsequently distilling the mixture at the same pressure into a stream comprising 2-butanol and a strea

Abstract: Process for the separation of a mixture comprising at least one hydrofluoroalkane and hydrogen fluoride, according to which a hydrofluoroalkane/hydrogen fluoride mixture is reacted with at least one chlorinated or chlorofluorinated precursor of the hydrofluoroalkane. Process for the preparation of a hydrofluoroalkane comprising such a separation, in combination with a catalytic reaction stage. Azeotropic compositions.

Abstract: A method for effectively preventing polymerization of acrylic acid during an azeotropic dehydration distillation in an acrylic acid manufacturing process and thus enabling stable operation of the azeotropic dehydration column over an extended period of time. The acrylic acid is separated in an azeotropic dehydration column from an acrylic acid aqueous solution fed therein, and the method includes withdrawing from the bottom of the azeotropie dehydration column a bottom effluent containing 50% or more of glyoxal (including the hydrates thereof) contained in the acrylic acid aqueous solution fed into the azeotropic dehydration column.

Abstract: An amine-containing mixture containing one or more amines, water, low-boilers and optionally high-boilers is fractionated by a process having the steps (iii) and (iv) and optionally the steps (i), (ii) and (v): (i) a (first) low-boiler fraction is separated off from the amine-containing mixture by distillation, (ii) a (first) high-boiler fraction is separated off from the amine-containing mixture by distillation, (iii) the amine-containing mixture is extracted with sodium hydroxide solution, producing an aqueous, sodium-hydroxide-containing first phase and an aqueous-organic, amine-, (further) low-boiler- and possibly (further) high-boiler-containing second phase, (iv) the aqueous-organic second phase, is distilled, producing essentially anhydrous amine as bottom-phase take off or sidestream takeoff in the stripping part of the distillation column, an amine/water azeotrop as sidestream takeoff in the enrichment part of the column and a (further) low-boiler fraction as overhead takeoff, and recycling the amin

Abstract: The invention relates to a method for removing, by distillation, 6-aminocapronitrile from mixtures that contain 6-aminocapronitrile, adipodinitrile and hexamethylenediamine, by a) removing the hexamethylenediamine from the mixture while obtaining a mixture (I) that has a hexamethylenediamine content of less than 1 wt. -%, b) removing completely or partially the 6-aminocapronitrile from mixture (I) while obtaining a mixture (II) whose content in substances that have a higher boiling point as 6-aminocapronitrile under distillation conditions and that cannot be formed by dimerization reactions when 6-aminocapronitrile is thermally treated is less than 1 wt. -%, and c) completely or partially removing from mixture (II) the hexamethylenediamine that might be present while obtaining a mixture (IV) whose hexamethylenediamine content is higher than that of mixture (II), and a mixture (V) whose hexamethylenediamine content is lower than that of mixture (II).

Abstract: Process for producing a nitric acid of a concentration from 75 to 99.9% from a more diluted nitric acid, wherein a nitric acid of a concentration of about 45 to 70% is rectified in contact with a liquid extraction medium to prevent the formation of a nitric acid-water-azeotropic mixture, and the vapors of the concentrated nitric acid are condensed and a concentrated nitric acid is obtained and wherein additionally the extraction medium is reconstituted through reconcentration and returned into the extractive rectification, wherein the nitric acid to be concentrated is fed as a boiling liquid or partially vaporized to the extractive rectification preferably carried out in two columns (K 1.0, K 1.

Abstract: The invention relates to a process for recovering and producing chemicals in a pulp production process where organic chemicals, such as formic acid and acetic acid, are used as cooking chemicals. The process of the invention is based on regeneration of cooking acids and formation of additional cooking acids and furfural by evaporating the cooking liquor and then separating acetic acid, formic acid, furfural and water. The separation is preferably carried out by distillation using the furfural formed in the process as a distilling aid in the distillation.

Abstract: An organic solvent is separated from a waste stream containing supercritical CO2, an organic solvent and etchant contaminants. The process includes separating the supercritical CO2 by subjecting the waste stream to elevated temperature and/or reduced pressure to thereby obtain a first composition containing the supercritical CO2 and a second composition containing the organic solvent and being substantially free of the supercritical CO2; and then removing non-volatile etching contaminants from the second stream search as by at least one of the following: evaporation; distillation; filtration; centrifugation; and settling.

Abstract: A mixture containing one or more amines, water, low-boilers and high-boilers, is fractioned in a process wherein (i) low-boilers are separated from the mixture by distillation, (ii) high-boilers are separated from the mixture by distillation, (iii) the mixture is extracted with a sodium hydroxide solution to form an aqueous, sodium-hydroxide-containing first phase and an aqueous-organic, amine-containing second phase, and (iv) the aqueous-organic second phase is distilled to form an amine/water azeotrop and an essentially anhydrous amine, and the amine/water azeotrop is recycled to the extraction step (iii).

Abstract: A process for distillative removal of ammonia from solutions (I) which include a lactam and ammonia comprises effecting said removal in a distillation apparatus (a) at an absolute pressure of less than 10 bar.

Abstract: To improve the columns used so far for producing phthalic anhydride, and to make them less expensive and easier to install, it is proposed that in the column for concentrating phthalic anhydride two distillation stages are arranged, wherein the removal of the low-boiling components of the crude phthalic anhydride by distillation is effected in the first distillation stage (2) and the separation of the high-boiling components from the pure phthalic anhydride is effected in the second distillation stage (3), both distillation stages being arranged side by side and being separated from each other by a vertical wall (4), and that the bottom (7) of the first distillation stage (2) is connected with the bottom (10) of the second distillation stage (3).

Abstract: A process for the separation of diisobutylene from tertiary butyl alcohol utilizing pressure swing azeotropic distillation to achieve the desired separation. The pressure swing azeotropic distillation takes advantage of the fact that different azeotropes are formed at different pressures. Isobutylene in C4 streams is oligomerized in the presence of tertiary butyl alcohol to produce the diisobutylene. Tertiary butyl alcohol is present in the dimerization because it improves the selectivity to the dimer (diisobutylene) by suppressing further reaction to the trimer or higher. The diisobutylene is separated from the tertiary butyl alcohol utilizing two distillation columns. The first distillation is operated at a higher pressure than the second such that the minimum boiling azeotropes of tertiary butyl alcohol and diisobutylene have different concentrations of tertiary butyl alcohol. Diisobutylene is removed as bottoms from the first distillation column and unreacted C4's are removed as overheads at 60-130 psig.

Abstract: There is provided an azeotropic mixture having 1,1,1,3,3-pentafluoropropane and hydrogen fluoride. Further, there is provided a process of separating/purifying R-245fa and/or HF from a mixture of R-245fa and HF wherein the mixture of 1,1,1,3,3-pentafluoropropane and hydrogen fluoride is subjected to a distillation step so that a distillate is obtained which has the azeotropic mixture of 1,1,1,3,3-pentafluoropropane and hydrogen fluoride, and a bottom product is obtained which has separated/purified 1,1,1,3,3-pentafluoropropane or hydrogen fluoride.

Abstract: The present invention relates to a process for preparing anhydrous hydrazine. The process can include distilling an unconcentrated aqueous hydrazine solution into a starting binary solution, distilling the starting binary solution at a pressure where a concentration of hydrazine in the binary solution is greater than a concentration of an azeotrope at the distillation pressure, and recovering the anhydrous hydrazine.

Abstract: 1,1-Difluoroethane containing less than 10 mg/kg of vinyl chloride is obtained by treatment, with hydrogen fluoride, of a crude 1,1-difluoroethane containing less than 1 mol of hydrogen chloride per mole of 1,1-difluoroethane.

Abstract: A process for the preparation of propylene oxide in the presence of methanol, in which propylene oxide is separated from a mixture propylene oxide and methanol, and the resultant methanol containing mixture is worked up, including seperating methanol from a mixture comprising methanol and methyl formate during the work-up.

Abstract: In a process for the continuous fractional distillation of mixtures comprising tetrahydrofuran, ?-butyrolactone and/or 1,4-butanediol to give at least three fractions, the fractionation is carried out in an assembly of distillation columns comprising at least one dividing wall column or at least one assembly of thermally coupled conventional distillation columns.

Abstract: A process of treating waste solvent acetonitrile streams which contain at least one water extractable impurity such as isopropyl acetate to remove substantially all of the impurity by distilling the waste solvent acetonitrile in the presence of water for a time sufficient to allow the water extractable impurity to be extractively distilled from the acetonitrile. In preferred embodiments of the present invention the feed may contain either a mixture of waste solvent acetonitrile and crude acetonitrile or crude acetonitrile free of hydrogen cyanide by itself.

Abstract: This invention relates to processes for the production of tocotrienol compounds from biological sources such as palm oil, cereals, grains, and grain oils. The tocotrienol products are recovered in high yields. These tocotrienols are useful as pharmaceuticals, in foodstuffs and as dietary supplements. These compositions are hypocholesterolemic, antioxidizing, antithrombotic, antiatherogenic, antiinflammatory and immunoregulatory in nature. Tocotrienols are known to lower the levels of low density lipoproteins in the bloodstream.

Abstract: A mixture containing mixture one or more amines, water, low-boilers and high-boilers, is fractioned in a process wherein (i) low-boilers are separated from the mixture by distillation, (ii) high-boilers are separated from the mixture by distillation, (iii) the mixture is extracted with a sodium hydroxide solution to form an aqueous, sodium-hydroxide-containing first phase and an aqueous-organic, amine-containing second phase, and (iv) the aqueous-organic second phase is distilled to form an amine/water azeotrope and an essentially anhydrous amine, and the amine/water azeotrope is recycled to the extraction step (iii).

Abstract: The present invention relates to a method of treating condensates containing compounds, which are more volatile than water, in an evaporation plant, where liquid, such as effluent liquid from a pulp or paper mill is evaporated in multiple effects and where condensates generated in the evaporation are flashed and purified in a steam stripping column. In the method, the condensates from at least two evaporation effects are combined and flashed together, and the vapor obtained from the flashing is made to contact with a condensate stream to be purified in the stripping column, wherefrom the impurities-containing vapor and the purified condensate stream are discharged.

Abstract: This invention is an improved distillation sequence for the separation and purification of ethylene from a cracked gas. A hydrocarbon feed enters a C2 distributor column. The top of the C2 distributor column is thermally coupled to an ethylene distributor column, and the bottoms liquid of a C2 distributor column feeds a deethanizer column. The C2 distributor column utilizes a conventional reboiler. The top of the ethylene distributor is thermally coupled with a demethanizer column, and the bottoms liquid of the ethylene distributor feeds a C2 splitter column. The ethylene distributor column utilizes a conventional reboiler. The deethanizer and C2 splitter columns are also thermally coupled and operated at a substantially lower pressure than the C2 distributor column, the ethylene distributor column, and the demethanizer column. Alternatively, a hydrocarbon feed enters a deethanizer column.

Abstract: The present invention relates to a process for separating secondary butanol (also referred to as 2-butanol or SBA below) from tert-butanol/water mixtures which are obtained in the dissociation of tert-butanol (TBA), in particular tert-butanol prepared from industrial C4-hydrocarbon mixtures, into isobutene and water.

Abstract: The invention relates to a method for separating and purifying an aqueous mixture that mainly consists of acetic acid, formic acid and high-boiling substances by extraction with a solvent in a cyclic process. The inventive method is characterized in that the flow of raffinate is fed to a solvent stripping column (11) with the major part of the water in order to remove the water from the cycle. The flow of extract is fed to a solvent recovery distillation column (8). In a first step, a mixture (A) that consists of water and solvent, is separated by overhead distillation. A mixture (B) that consists of acetic acid, formic acid and high-boiling substances is separated via a sump. Once the formic acid is removed in a column (29), mixture (B) is separated in an acetic acid distillation column to give pure acetic acid and high-boiling substances.

Abstract: A method for the purification of crude acetonitrile comprising distilling the crude acetonitrile in a first fractional distillation column at below atmospheric pressure, withdrawing a first side draw fraction comprising acetonitrile, distilling the first side draw fraction in a second fractional distillation column at super atmospheric pressure, and withdrawing from the second distillation a second side draw fraction comprising purified acetonitrile.

Abstract: A method for obtaining high purity N-(2-hydroxyethyl)-2-pyrrolidone satisfactory for use as an intermediate material for N-vinyl-2-pyrrolidone from a reaction liquid formed of a reaction between y-butyrolactone and 2-aminoethanol, i.e., a liquid containing N-(2-hydroxyethyl)-2-pyrrolidone, compounds having boiling points lower than that of N-(2-hydroxyethyl)-2-pyrrolidone and compounds having boiling points higher than that of N-(2-hydroxyethyl)-2-pyrrolidone. The method is characterized by distilling said reaction liquid using a distillation column, whereby obtaining a liquid containing the compounds having the lower boiling points than that of N-(2-hydroxyethyl)-2-pyrrolidone and N-(2-hydroxyethyl)-2-pyrrolidone as a distillate liquid from the column top and a liquid containing compounds having boiling points higher than that of N-(2-hydroxyethyl)-2-pyrrolidone as a bottom liquid.

Abstract: The present invention provides a continuous process for recovering acetone from a waste stream from an acetone purification stage, whereas said waste stream comprises mesityl oxide and optionally acetone by separating the waste stream in a separating device at least in one stream comprising mesityl oxide and optionally a further stream comprising acetone, by than concentrating mesityl oxide in the mesityl oxide containing stream and finally by recycling the concentrated mesityl oxide stream to the separating device and bringing it into contact with a basic or acidic aqueous medium or with an acidic catalyst in the presence of water whereby mesityl oxide is at least partially hydrolyzed to acetone.