Abstract: The invention relates to a distillation and reaction device having a reaction section and a distillation-reaction section. The distillation-reaction section has a distillation zone with at least one device for circulation of the effluent from the reaction section to the distillation zone. Effluent from the reaction section is circulated to the distillation zone. The distillation-reaction section also has at least one distillation-reaction zone having at least one catalyst bed. The distillation-reaction zone is distinct from the distillation zone and provides at least partly the reflux of the distillation zone. The distillation-reaction section can also have at least one complementary reaction zone containing at least one catalyst bed. The invention further relates to a process for preparing at least one aliphatic monoalcohol, generally in excess, and at least one olefin.

Abstract: A process for recovering hexamethylenediamine (I) from a mixture (II) including(I) hexamethylenediamine,(III) hexamethyleneimine,(IV) a compound selected from 2-aminomethylcyclopentylamine and 1,2-diaminocyclohexane,(V) an imine,(VI) adiponitrile and 6-aminocapronitrileincludes distilling(a) a mixture (II) to obtain(a1) a low boiling fraction (III),(a2) a medium boiling fraction (VII) (I), (IV) and (V), and(a3) a high boiling fraction (V) and (VI),(b) a mixture (VII) to obtain(b1) an overhead product (IV), and(b2) a mixture (VIII) (I) and (V) as bottom product, and(c) a mixture (VIII) to obtain(c1) (I) as overhead product, and(c2) a bottom product (V).

Abstract: A process for distilling ethylene oxide out of a mixture including ethylene oxide in a column at an absolute pressure of from 2 to 10 bar and a temperature of 20 to 180.degree. C. by withdrawing pure ethylene oxide in the liquid or gaseous state overhead or via a sidestream in the rectifying section of the column includes effecting the distillation in a column having on its inside a plurality of successive zones of structured sheet-metal packing or dumped beds of packing elements, these zones being assigned one or more extinguishing systems on the outside of the column.

Abstract: The present invention teaches an efficient and easier to operate distillation system to separate mixtures containing three or more components into streams enriched in one of the components. In this invention, a liquid stream enriched in the least volatile component is withdrawn from the bottom of one distillation column while a vapor stream enriched in the most volatile component is withdrawn from the top of another distillation column. Of these two distillation columns, the pressure of the distillation column with the bottom liquid enriched in the least volatile component is higher; and this higher pressure distillation column transfers at least two vapor streams from different locations to either one or more other distillation columns within the distillation system. For a ternary mixture, both the vapor streams are transferred to the distillation column with the top vapor enriched in the most volatile component.

Abstract: This invention relates to a process for the simultaneous co-production of ethyl acetate and n-butyl acetate. The process involves reacting a reaction mixture of ethanol, n-butanol and acetic acid in the liquid phase, in the presence of an acidic catalyst. The process is carried out in a series of reactor and distillation columns. The process is capable of using relatively impure reactants and provides for removing some of the aldehyde type impurities by the use of resin guard beds.

Abstract: A system and process for purifying a 1,3-butadiene feedstock containing 1,3-butadiene and various impurities by first introducing the 1,3-butadiene feedstock stream to a separation column to produce an intermediate product stream containing 1,3-butadiene and residual impurities and then introducing the produced intermediate product stream through a condenser to a suitable dryer for removing residual impurities from the intermediate product stream and thereby forming a purified 1,3-butadiene stream. The separation column separates an overhead stream, containing 1,3-butadiene and impurities such as propadiene, water and oxygen, and a bottoms stream, containing impurities such as polymerization inhibitor, ethyl acetylene, 1,3-butadiene dimer, pentane and 1,2-butadiene, from the intermediate product stream which leaves the separation column in the form of a vapor side draw stream.

Abstract: Neopentyl glycol hydroxypivalate (NGH) is isolated from a mixture containing NGH, lower- and higher-boiling products and inorganic salts and purified in a two-stage process, whereinin a first separation stage, the inorganic salts and part of the higher-boiling products are separated off in a wiped-film evaporator and a vapor stream consisting of NGH, lower- and higher-boiling products is discharged and fed to a heat exchanger and condensed therein,and, in a second separation stage, the resulting condensate is distilled in a rectification column from which NGH is taken off in a side stream and condensed. Further discharges of the rectification column containing lower-boiling products or higher-boiling products are separately taken off. The higher-boiling products which comprise residual NGH are partly or completely recycled to the lower region of the rectification column.

Abstract: A process for preparing high-purity cyclopropyl methyl ketone from compositions which contain cyclopropyl methyl ketone, 4,5-dihydro-2-methylfuran, addition products of 4,5-dihydro-2-methylfuran by a continuous rectification process in which at least a portion of the composition to be purified is introduced into a rectification apparatus via a side feed located above the bottom portion of the apparatus.

Abstract: In a process for the purification by distillation of chlorinated aromatic hydrocarbons originating from the chlorination of aromatic hydrocarbons in the presence of FeCl.sub.3, the crude reaction product is first partially degassed and then directly subjected to distillation in the presence of said FeCl.sub.3.

Abstract: Butanol and dibutyl ether are separated from a mixture containing water, dibutyl ether and n-butanol, 2-butanol and/or isobutanol by a process in whicha) the mixture is introduced into a first distillation column, essentially butanol is separated off at the bottom of this distillation column and the mixture taken off at the top of the distillation columnb) is introduced into a second distillation column and essentially dibutyl ether is separated off at the bottom of this second distillation column and the mixture formed at the top of the second distillation column is removed,c) the second distillation column being operated at a higher pressure than the first distillation column and at least one of the two mixtures taken off via the top of the distillation columns being subjected to phase separation, only the organic phase separated off being fed to the second distillation column in the case of phase separation downstream of the first distillation column, and separation into an aqueous and an organic phase als

Abstract: An improved process for preparing an aromatic dicarboxylic acid wherein the improvement resides in dehydrating and recovering solvent from a feed stream having from 20% to 40% by weight water via azeotropic distillation with organic phase reflux using an entrainer selected from isobutyl acetate, n-propyl acetate or an entrainer with a boiling point between isobutyl acetate and n-propyl acetate.

Abstract: Natural cresylic acid is processed to remove neutral oil impurities by countercurrent liquid/liquid extraction using a heavy phase solvent of a mixture of glycerol and another polyhydric alcohol, preferably triethylene glycol. The light phase solvent is a light paraffinic or cycloparaffinic hydrocarbon.

Abstract: A method of distilling a crude oil and a contaminated liquid stream in an atmospheric distillation column (2) comprising the steps of (a) heating (13, 15) the crude oil at atmospheric pressure and introducing the heated crude oil into the inlet section (10) of the column (2); (b) removing from bottom a residue (19), removing from the top an overhead (20) and removing from the rectification section (7) at least one side stream (26, 28); (c) cooling (13) one of the side streams (28) and introducing the cooled side stream (29) into the rectification section (7) and partly condensing (21) the overhead (20) and introducing the condensed fraction (24) into the upper end of the distillation column (2); (d) supplying the contaminated liquid stream (40) to a membrane unit (3) provided with a suitable membrane (33), and removing a permeate (37) and a retentate (36); and (e) introducing the permeate (37) into the rectification section (7) and adding the retentate (36) to the crude oil (11) upstream of the furnace (1).

Abstract: In a process for the continuous distillation of thermolabile monomers under reduced pressure in the presence of formamide in a column,the thermolabile monomers are continuously fed in liquid form, separately from formamide, into the lower part of the column up to the middle of the column,Formamide is vaporized with a vaporizer at the bottom of the column and, together with constituents having higher boiling points than the thermolabile monomers, is discharged from the bottom of the column and replaced by addition of fresh formamide,the thermolabile monomers are taken off at a side offtake in the upper third of the column, with the distillation being controlled such that the monomers contain less than 5% by weight of formamide, anda product stream containing constituents which have a lower boiling point than the thermolabile monomers is taken off at the top of the column.

Abstract: To reduce the benzene content of a hydrocarbon mixture that contains benzene and other hydrocarbons, the mixture is fed to a distillation column so as to separate an overhead distillate, a bottom residue, and a sidestream having a benzene content richer than in the distillate and in the residue; the resultant sidestream is sent to at least one permeation zone to permeate the benzene selectively and retain a retentate having a reduced content of benzene; and at least part of the retentate is recycled to at least one level in the distillation column, preferably two levels, one at above and one below the feedpoint to the column. The permeate benzene stream is optionally subjected to extractive distillation in order to increase the purity of the resultant benzene.

Abstract: A distillation column suitable for the separation of a three component feed mixture is provided wherein the fractional distillation column utilizes a vertical partition and a baffle to prevent feed mixture from taking a direct flow path from the feed inlet to the sidedraw exit. The use of the vertical partition increases the separation purity of the middle boiling fraction and lower boiling fraction.

Abstract: Gases and liquid products of the cracking zone of a ethylene production plant fractionated in a demethanizer to from a dilute ethylene stream containing about 5 to about 40 percent of the ethylene contained in the feed. The dilute ethylene is feed to an ethylbenzene plant and reacts with impure benzene. The product ethylbenzene is normally converted to styrene.

Abstract: An aqueous solution of free hydroxylamine is prepared by a process in which the solution obtained by treating a hydroxylammonium salt with a base is separated into an aqueous hydroxylamine solution and a salt fraction by treatment with water or steam at .ltoreq.80.degree.0 C. The novel process can be carried out in a simple and gentle manner and on a large industrial scale. Owing to the low thermal load, the low concentration of hydroxylamine and the short residence time in the process, the risk of decomposition is minimized.

Abstract: A liquid and vapor phase processes for the production of difluoromethane in which the risk of exposure to, and equipment fouling from, chlorofluoromethane is reduced. This reduction is accomplished from removing a sidestream containing monochloromonofluoromethane from a fluorination process distillation column.

Abstract: In a distillation column for separating a liquid mixture into a plurality of pure fractions, the distillation column being divided into 2 parts, a feed part and a take-off part, in its middle region by a separation effective in the longitudinal direction, the separation consists of two walls with a gas space in between, the distance between the two walls being from 1 to 50 mm, preferably from 3 to 10 mm.

Abstract: The production of high purity benzene and high purity toluene is obtained by utilizing the initial gas separating column for the treatment of the aromatic containing starting material as a separating column for separating a benzene rich from a toluene rich component. The benzene rich component is subject directly to distillation while the toluene is subject to predistillation to separate high boiling components and only then to extractive distillation is distilled to separate the high purity benzene from the high purity toluene.

Abstract: Separation of 1,1-dichloro-1-fluoroethane (141b) from lower boiling components contained in a crude 141b feed stream mixture by adding the feed stream mixture, and, based upon the weight of 141b in the feed stream mixture, between 100 and 300 ppm of a component that will inhibit formation of 1,1-difluoro-1-chloroethane into a feed line of a distillation column operated at between 3 and 165 psig pressure with a temperature between 100.degree. F. and 250.degree. F. in the bottom reboiler section of the column.

Abstract: A process for preparing a high purity H.sub.2 O.sub.2 aqueous solution, which comprises the steps of: (a) feeding a crude H.sub.2 O.sub.2 aqueous solution containing H.sub.2 O.sub.2, organic carbon impurities and inorganic impurities into a distillation column having an inner wall at least the surface of which is made of a fluorine resin and internals and packings at least the surface of which are made of a fluorine resin being provided internally of the distillation column, from a bottom portion of the distillation column; (b) subjecting the crude hydrogen peroxide aqueous solution to distillation under reduced pressure and under heating the bottom portion; (c) taking out a distillate containing an extremely low concentration of H.sub.2 O.sub.

Abstract: A process for the separation of a mixture which contains benzyl chloride, benzyl alcohol, dibenzyl ether and aqueous hydrochloric acid, wherein said mixture is continuously introduced via a side-feed into a distillation column from which aqueous hydrochloric acid and benzyl chloride are continuously taken off as overhead product, benzyl alcohol and dibenzyl ether are continuously taken off as bottom product, thereby the formation of dibenzyl ether is reduced or virtually prevented.

Abstract: A process by which iodine compounds contained in crude acetic anhydride or a mixture of crude acetic anhydride and crude acetic acid can be converted into methyl iodide having a low boiling point and which can be separated by distillation and efficiently removed by the combination of the conversion step with the heat treatment step and distillation step. The process includes the steps of heat-treating the crude acetic anhydride or the mixture of crude acetic anhydride and crude acetic acid in the presence of methanol and/or methyl acetate in a treatment tank and distilling the heat-treated crude acetic anhydride or the heat-treated mixture of crude acetic anhydride and crude acetic acid, in the presence of an alkali metal salt and/or an alkaline earth metal salt if necessary.

Abstract: The invention concerns a process and an apparatus for preparing tertiary ethers. According to the process, C.sub.4 to C.sub.6 isoolefins and possibly heavier olefins contained in the feedstock are reacted with lower aliphatic alcohols, in particular methanol or ethanol, in a catalytic distillation reactor system in order to produce the corresponding ethers. According to the invention, the reaction between the isoolefins and the alcohols is essentially carried out in at least one reactor (5-7) of the kind, which is combined with a distillation column (3) intended for product separation, by conducting at least a part of the liquid flow of the column through the reactor and returning it to a lower tray than the one from which it was taken. At least half of cation exchange resin is placed in the side reactor (5-7). In the process according to the invention, the catalyst can be rapidly changed without stopping the process.

Abstract: A process for separating a mixture containing mainly ethyl tertio-butyl ether (ETBE), ethanol and C.sub.4 hydrocarbons includes introducing the mixture to be separated into a debutanizer from which the C.sub.4 hydrocarbons are recovered overhead with a fraction of the ethanol, and purified ETBE is recovered as a bottom product; a side stream of an ethanol-rich phase is extracted and sent to a permeation zone in which the dense film of the membrane is constituted by a N,N-dimethylaminoethyl methacrylate polymer (DMAEMA) or a copolymer of DMAEMA with N-vinylcaprolactam (NVCL) and/or with N-vinyl pyrrolidone (NVP); the ethanol-depleted retentate from this permeation zone is returned to the debutanizer and the permeate contains mainly separated ethanol.The process can be integrated into an ETBE production process, in which the ethanol separated during the permeation step is recycled to the etherification reactor. The debutanizer may be replaced by a catalytic distillation column.

Abstract: A method and apparatus for quenching a gas stream in the production of vinyl chloride monomer includes the use of a knock back condenser and a plurality of column fractional distillation trays disposed within the quench column, and a liquid stream of 1,2-dichloroethane, vinyl chloride, and hydrogen chloride may be removed from the bottom column fractional distillation tray.

Abstract: An apparatus and method are provided for the defluorination of a liquid hydrocarbon mixture, containing organic fluorides, produced during the conversion of hydrocarbons using a fluorine-containing catalyst. In one embodiment, both a thermal means and a contacting material are used to effectuate a more complete defluorination. The liquid hydrocarbon mixture is extracted from a distillation column and heated sufficiently in the thermal means to decompose at least some of the organic fluorides. The effluent from the thermal means is separated into a vaporous and a liquid effluent. The liquid effluent is passed to the bottom of the distillation column where it undergoes further defluorination through contact with the contacting material.

Abstract: From a mixture containing methanol, ethanol, n-propanol, isobutanol water and other high-boiling and low-boiling compounds, the claimed process enables three separate streams to be obtained, one an anhydrous stream of methanol or methanol and ethanol (I), one containing most of the n-propanol present in the feed mixture (II), and one containing most of the isobutanol present in the feed mixture (III), by using three fractionating columns.

Abstract: The invention relates to an improved method and a novel apparatus for the concentration, separation, and purification of contaminated chemical compounds, wherein the chemical compound is less volatile than the contaminant. The distillation is performed using constant, predetermined distillation parameters.

Abstract: A thermomechanically integrated distillation column and method for the separation of ethylene from ethane and other close-boiling light hydrocarbons. The column has a plurality of sections operated at successively lower pressures from a high pressure subcritical section to a superatmosphere bottoms product zone. Bottoms liquid from the high pressure and intermediate sections are flashed in respective cooling loops to about the pressure of the section of next lower pressure, vaporized in heat exchange with an overhead condensing zone and introduced to the top stage of next lower pressure section. Vapor from the intermediate sections and the bottoms product zone are compressed in respective compression loops and fed to the bottom stage of the section of the next higher pressure. External refrigerant can be supplied to the overhead condensing zone for trim as needed for control purposes.

Abstract: A method for recovering 1,4-butanediol from a hydrolysate obtained by hydrolyzing diacetoxybutane, by (1) supplying the hydrolysate to a first distillation column, distilling off substantially all the amounts of water and acetic acid as the top stream from the first distillation column, and supplying a bottom liquid to a second distillation column, (2) distilling off diacetoxybutane and hydroxyacetoxybutane as the top or upper side stream from of the second distillation column, and circulating the distillates to a hydrolysis zone, while withdrawing crude 1,4-butanediol as a lower side stream in vapor phase from the second distillation column, (3) supplying the crude 1,4-butanediol and hydrogen gas to a hydrogenation reaction zone packed with a hydrogenation catalyst, and (4) supplying the hydrogenation reaction product to a third distillation column, distilling off low boiling point components and withdrawing 1,4-butanediol as the bottom or side stream from the third distillation column.

Abstract: Acetic acid and/or acetic anhydride containing methyl crotonate, vinyl acetate, or both as impurities, is contacted with ozone in an amount of excess molar to the carbon-carbon double bond in said methyl crotonate and/or vinyl acetate and the impurities produced by ozone-treatment are removed off by distillation. A large quantity of impurities such as aldehydes are produced after treatment by treating acetic acid and/or acetic anhydride containing much amount of unsaturated compounds as impurities with ozone. Distilling the ozone-treated acetic acid and/or acetic anhydride make it possible to remove methyl crotonate and vinyl acetate, which are unsaturated compounds difficult to remove by the conventional separation methods, to give high-quality acetic acid and/or acetic anhydride excellent in the residence time in the potassium permanganate test.

Abstract: For separating ETBE and ethanol the following principal stages are employed:(1) Extraction of ethanol by water, the raffinate being ETBE saturated in water and the extract an ethanol/water mixture containing a small proportion of ETBE;(2) Concentration of the above mixture, the distillate being a mixture close to the ethanol/water azeotrope in composition and containing a very small proportion of ETBE;(3) Heteroazeotropic distillation of this distillate in two coupled columns with an overhead decanter, this distillation using ETBE as azeotroping agent; the residue of the first column being ethanol which is ca. 99% by mole and the residue of the second column being practically pure water, this water and the water recovered during the concentration stage being used as extraction solvent in stage (1).Stage (3) may be an ethanol dehydration unit using ETBE as dehydrating agent.

Abstract: A methanol refining column and method using an intermediate reboiler. Use of the intermediate reboiler reduces methanol production energy requirements. A side stream at or near a fusel oil takeoff point is heated in an intermediate reboiler by a low temperature heating medium (relative to a bottoms reboiler) and returned to the column at or near the fusel oil take-off tray. The take-off tray is operated at 85.degree.-110.degree. C., and 70-90 percent of the reboiler duty is supplied through the intermediate reboiler. The remaining heat load is supplied by a bottoms steam reboiler.

Abstract: A process for the separation of 1,4-butanediol from mixtures obtained by the catalytic hydrogenation of maleates, fumarates, and/or succinates, which also contain tetrahydrofuran, water, C.sub.1 -C.sub.4 alcohols, succinic diesters, hydroxybutyrates, alkylhydroxyalkyl succinates, gamma-butyrolactone and butyrates, in addition to 1,4-butanediol, comprising the following steps:a) separating, in a first column having an actual number of plates of from 20 to 70 and operated at a top pressure of from 50 to 1100 mbar and preferably from 50 to 500 mbar and a top temperature of from 40.degree. to 120.degree. C., alcohol, water and tetrahydrofuran, as overhead product,b) feeding the bottom product of the first column into a second column having an actual number of plates of from 30 to 90 and withdrawing the overhead product consisting of alcohol and butyrate and obtained at a top pressure of from 45 to 250 mbar and a top temperature of from 45.degree. to 120.degree. C.

Abstract: In a distillation column with vaporous sidestream removal, the vaporous product removed is condensed in a condenser. The vapor pipe provided for the removal of product opens into a dip tank of which the upper end is connected to the condenser while its lower end is connected to a discharge pump. Inert gas present in the condensate is returned to the column above the sidestream removal through an inert gas pipe arranged at the upper end of the condenser.

Abstract: This invention relates to a process for producing odourless dimethyl ether (DME) which is thus an excellent propellant. This dimethyl ether is produced from methanol, the methanol feed, prior to the reaction to form dimethyl ether, and/or the dimethyl ether product still containing odorants being treated with acidic materials, preferably acidic ion exchangers.

Abstract: Process for obtaining purified hydrogen peroxide solutions, consisting in evaporating the crude aqueous hydrogen peroxide solution containing the impurities and feeding by means of the vapour phase produced the foot of a distillation column provided in its lower part with a zone for washing the vapour phase with a small flow of liquid which refluxes in the bottom of the column and which has the same composition as the purified aqueous hydrogen peroxide solution forming the product leaving the column, in drawing off this purified product at a column height such that the draw-off is carried out above the vapour phase washing zone and in collecting at the bottom of the column a residue consisting of the small flow of washing liquid which contains most of the impurities. The washing zone has a diameter which is greater than that of the remainder of the column.Distillation column for carrying out the process.

Abstract: Disclosed is a continuous method for refining acetic anhydride produced by the reaction of ketene and acetic acid by means of a vacuum distillation system to provide a refined material comprised of at least 99.5 weight percent acetic anhydride, not more than 0.5 weight percent acetic acid and not more than about 90 parts per million (ppm) diketene.

Abstract: Where side stream distillate strippers are used in the distillation of hydrocarbons, the required size of the distillation column and the amount of stripping gas or vapor required are reduced by passing components stripped from the distillates through a plurality of strippers in series, rather than directly back to the distillation zone.

Abstract: A method of continuously distilling off the components of a mixture containing phenols, water and methanol using a single distillation column, wherein methanol is recovered from the top of the column, water containing phenols is dragged as a side stream from a recovery section of the column, and phenols are recovered as a bottom product. The method permits efficient separation by the single distillation column of the three components with high purity and low utility energy.

Abstract: A process for removing acetone from an acetone/methyl acetate/methyl iodide mixture utilizing extractive distillation with water being introduced to the distillation zone above the point of introduction of the mixture and acetic acid being introduced at or above the point of introduction of the mixture. In a preferred embodiment the mixture is subjected to an initial extraction with an aqueous extractant to remove most of the methyl iodide.The process is particularly applicable to removing acetone by-product in carbonylation processes for the production of acetic anhydride.

Abstract: A process for the separation of multicomponent systems containing intermediate boiling substances in separating separating columns with side discharge, the temperatures T.sub.u and T.sub.o above and below the side discharge are measured on the column or inside the column and the temperature difference T.sub.u -T.sub.o is used for controlling the side discharge. The control is carried out by constantly controlling one of the two temperatures T.sub.u or T.sub.o by the output of the evaporator or the discharge from the sump or the reflux or the removal of distillate or the reflux ratio.

Abstract: Disclosed is an improved process for the removal of acetone from a production system wherein acetic anhydride is produced by contacting a mixture comprising methyl iodide and methyl acetate and/or dimethyl ether with carbon monoxide in the presence of a carbonylation catalyst or catalyst system. The process comprises two distillation steps wherein acetone is separated from a mixture of methyl acetate, methyl iodide and acetone.

Abstract: An improved process for separation of valuable components of a waste stream resulting from production of an olefin polymerization procatalyst by the addition to the waste stream of a separation solvent of intermediate boiling point, subjecting the resulting mixture to a first distillation zone to separate the desired waste stream components from the upper portion of the zone and passing the bottoms product to a second distillation zone wherein separation solvent is recovered from the upper portion of the zone for recycle and passing the bottoms product to disposal or further processing.

Abstract: A process for separating phenol obtained by the decomposition of cumene hydroperoxide from high boiling impurities, includes the following steps:a) feeding phenol rectification bottoms comprising phenol, acetophenone, cumylphenol, alpha-methylstyrene dimers and high boiler residues to a first phenol freeing distillation column A;b) feeding concentrated bottoms with substantially reduced phenol content from column A to a second residue concentration distillation column B;c) withdrawing a stream rich in compounds boiling between phenol and residue, particularly cumylphenol, from said column B from a point below the feed and returning at least a portion of said stream to said column A at a point above the feed;d) recovering overheads from column A comprising at least 95 weight percent phenol; ande) recovering acetophenone-rich overheads from column B comprising at least 70 weight percent acetophenone.

Abstract: The method of obtaining a pure aromatic hydrocarbon from a hydrocarbon starting mixture includes extractively distilling the hydrocarbon starting mixture with a selective solvent; feeding the sump product of the extractive distillation through a first and second auxiliary boilers connected in series to form a cooled sump product at a temperature from 105.degree. to 120.degree. C.

Abstract: A dimeric cyclic ester of an alpha-hydroxycarboxylic acid (lactide) is separated and recovered from a vapor product stream containing the cyclic ester, the corresponding lower-boiling hydroxycarboxylic acid (lactic), higher-boiling oligomeric hydroxycarboxylic acid and water without the use of solvents. More specifically, the vapor stream is condensed to obtain a condensate containing substantially all the cyclic ester, and the condensate is refined by distillation means alone to recover the cyclic ester substantially free of water, the alpha-hydroxycarboxylic acid and the higher-boiling oligomers.