Abstract: A process for the nondegenerative distillation of C.sub.6 -C.sub.24 -fatty acids, of the type obtained by splitting natural fats and oils or by synthetic processes, such as for example the oxidation of paraffins, the crude product is thermally dried under reduced pressure, the dried and heated crude product is subjected to fractional evaporation in falling-film evaporators, optionally in the presence of superheated steam, and the various vapor fractions are deposited in condensers. The thermal drying process is conducted at a temperature of 60.degree.-80.degree. C. and a pressure of 90-100 mbars. The de-watered crude product is fractionated in a film-forming evaporator and, after distillation, passes to a rectification column which condenses the low boiling constituents as the main runnings.

Abstract: Improved process for the separation of a hydrocarbon-containing feedstream comprising monomer, comonomer and diluent into separate product streams which comprises subjecting the feedstream to two-stage distillation provided with a common accumulation zone wherein the condensate from the accumulation zone serves as the source of feed for the second distillation and reflux for the first distillation. In a specific embodiment, a feed comprising ethylene, 1-hexene, and isobutane is separated into separate streams of 1-hexene, ethylene and isobutane, and isobutane for recycle to polymerization.

Abstract: Disclosed is a method for recovering pure aromatic substances from a mixture of hydrocarbons containing both aromatic and non-aromatic fractions. The input mixture is fed through an extractive stage provided with a preliminary distillation column. In the preliminary stage the aromatics-containing product is treated at a pressure up to 20 bar and a temperature up to 300.degree. C. The pressure is adjusted to a value at which the operational temperature of the preliminary stage is higher than the pressure and temperature in the extractive stage and the heat of the vapors discharged from the preliminary stage is used for heating the extractive stage.

Abstract: The disclosure relates to a process for separating the catalyst system from reaction mixtures which are obtained by reacting methyl acetate and/or dimethylether with carbon monoxide and optionally hydrogen at elevated temperatures to acetic anhydride and optionally ethylidene diacetate in the presence of a catalyst system consisting of carbonyl complexes of noble metals belonging to group VIII of the Periodic System, acetic acid, an organophosphorus or organonitrogen compound, methyl iodide and optionally compounds of carbonyl-yielding common metals, and which issue from the reaction zone under a pressure of 25 to 150 bars at a temperature of 100.degree. to 250.degree. C. More particularly, the reaction mixture coming from the reaction zone is introduced into a separator heated to 60.degree. to 140.degree. C. and released to a pressure of 0.5 to 3.

Abstract: Disclosed is a process for recovering a virtually water-free amine from an amine acid salt thereof. The process comprises a unique combination of phase separation stages practiced under mild heating and distillation stages. An amine product containing less than 0.2% water can be achieved by the present process. The feedstock for the process suitably is an acid scrub liquor used to scrub amine from a vapor stream thereof which has been used in a cold-box molding process in the foundry industry or in the cure of vapor permeation curable coatings in the coatings industry.

Abstract: A process for continuous rectification of a liquid mixture containing alcohols, particularly a liquid fermate, employs a plurality of distillation columns to which the liquid mixture is fed in parallel, and which have successively reduced operating pressures and temperatures from an initial one to a final one thereof. The top vapor distillate from the higher-pressure columns supplies driving heat to the sumps of the next successively lower-pressure columns. Direct steam at 130.degree. C. to 160.degree. C. is fed to the sump of the column operated at the highest pressure. Direct steam is generated by indirect heat exchange of water with the top vapor withdrawn from the columns, and the resulting direct steam is fed to the sumps of the next-lower-pressure columns. The apparatus can also include a section for the production of absolute alcohol.

Abstract: Block short-way evaporator with wiped-off film for vacuum and molecular distillation which is suitable for large-scale production. The evaporator is composed of one or more vacuum chambers in which parallel vertical double-sided flat evaporators with wipers for wiping evaporating areas and double-sided flat condensers are alternately located so that they form a continuous block. On the bottom of each chamber distillate collecting troughs with distillate tubes are formed alternately below double-sided flat condensers using separating partitions, and below double-sided flat evaporators residue collecting troughs with residue outlet tubes are formed, feed tubes being led through the bottom and the double-sided flat evaporators into separating troughs in the upper part of the double-sided flat evaporators.

Abstract: A C.sub.1 -C.sub.4 alkanol and its corresponding acetate or a C.sub.1 -C.sub.2 alkanol and its corresponding propionate are separated by extractive distillation utilizing an aromatic hydrocarbon as the extractive solvent. Transesterification of lower alkanols and lower alkyl acetates or propionates is effected by means of extractive distillation and the preparation of an intermediate ester of a higher boiling alcohol.

Abstract: Disclosed is a process for recovering a virtually water-free amine from an amine acid salt thereof. The process comprises a unique combination of phase separation stages practiced under mild heating and distillation stages. An amine product containing less than 0.2% water can be achieved by the present process. The feedstock for the process suitably is an acid scrub liquor used to scrub amine from a vapor stream thereof which has been used in a cold-box molding process in the foundry industry or in the cure of vapor permeation curable coatings in the coatings industry.

Abstract: This invention relates to a process for purifying crude ethanol, whether produced by fermentation or by the synthetic route, to produce a pure ethanol-water azeotrope. The process uses only two distillation columns for fermentation ethanol or synthetic ethanol eventhough the latter has diethyl ether as impurity. The inventive concept lies in the design and specification of the columns and the specific high pressure and low reflux ratio distillation conditions which enable each of the impurities in ethanol to be reduced below ppm. Ethanol of such purity is most desirable when used for potable or pharmaceutical purposes.

Abstract: A liquid containing a contaminant such as water or polymeric solids is purified. Purification of a liquid containing a contaminant is enhanced by the use of second fractionating column in conjunction with a first fractionating column to recover a portion of the liquid to be purified from the kettle product of the first column. Vapor from a second fractionating column is used to control the total energy input to a first fractionating column.

Abstract: Crude 2-methyleneglutaronitrile containing as impurities a metal halide, a trialkylamine, and the trimer or a higher polymer of acrylonitrile can be effectively purified by treating the crude 2-methyleneglutaronitrile with hydrochloric acid, sulfuric acid or nitric acid of a concentration of 1 to 30% by weight and then subjecting the treated methyleneglutaronitrile to vacuum distillation.

Abstract: A process is provided for the continuous separation of slightly volatile components from a crude phthalic acid anhydride wherein a portion of the crude phthalic acid anhydride is compressed and heated before being reintroduced into a flash evaporator.

Abstract: From an acrylonitrile-dimerization liquid product prepared by contacting acrylonitrile with a specific catalyst composed of a metal halide and a trialkylamine, 2-methyleneglutaronitrile is efficiently recovered by a process which comprises contacting the reaction liquid product under stirring with benzene, toluene or xylene as well as with water in specific ratios, and then separating the resulting aromatic hydrocarbon layer from the mixture to recover 2-methyleneglutaronitrile.

Abstract: An improved distillation method and apparatus are provided for recovering anhydrous ethanol from fermentation or synthetic feedstocks. The system includes at least one stripper-rectifier tower, a dehydrating tower, and an azeotropic agent stripping tower. Substantial energy savings are realized by operating the dehydrating tower, and preferably also the azeotropic agent stripping tower, at a higher pressure than the stripper-rectifier tower and by condensing the overhead vapors from the dehydrating tower (or dehydrating tower and azeotropic agent stripping tower) to provide the heat required in the stripper-rectifier tower. In a preferred embodiment, two stripper-rectifier towers are used, one operating at a higher pressure than the other, in which case the higher pressure tower is heated as just described and the overhead vapors from the higher pressure tower are condensed to supply the heat required in the lower pressure tower.

Abstract: Excess water and color-forming materials present in crude 1,4-butanediol are reduced by subjecting the crude 1,4-butanediol to distillation under conditions wherein substantially all the water present in the crude 1,4-butanediol is first removed and then the 1,4-butanediol with reduced water content is further refined by flash evaporation under vacuum.

Abstract: A new process for the production of very pure 4,4'-diisocyanatodiphenylmethane is disclosed, in which diisocyanatodiphenylmethane isomers which are obtained by distillation from the phosgenation products of aniline/formaldehyde condensates are initially freed from 2,2'- and 2,4'-isomers under certain distillation conditions and are then further worked-up by distillation, in that in a first final stage, from 50 to 90%, by weight of the diisocyanate freed from 2,2'- and 2,4'-isomers is isolated as the head product in the form of pure 4,4'-diisocyanatodiphenylmethane and in a second final stage, another quantity of pure 4,4'-diisocyanatodiphenylmethane is separated as the head product from the distillation of the sump of the first final stage.

Abstract: The energy requirements of a solution rubber process are significantly improved by employing solvent which has been removed in subsequent process steps.The invention concerns the separation treatment of the solvents and the polymer solutions produced by solution polymerization. In one embodiment a polymer solution is flashed to remove solvent vapor overhead and a concentrated polymer solution is removed as bottoms. The flashed solvent vapor is divided into at least two streams. A first stream is used as a stripping vapor medium in a zone for stripping a wet solvent to recover a wet solvent vapor overhead from the stripping zone and a dry solvent liquid as bottoms; the second flashed solvent vapor stream is used to preheat the wet solvent feed to the stripping zone by indirect contact heat exchange; a third portion of said solvent vapor can be combined with the second portion downstream of the heat exchange step, and the combined stream can be condensed.

Abstract: A method of recovering or extracting chemicals, such as furfural, formic acid, acetic acid and other organic compounds from acidic hydrolysates of plants or vegetable matter, especially spent sulfite liquors after conversion of the pentosans into pentoses and then into furfural by heating the hydrolysate in an acidic environment. The conversion of the pentosans pentoses into furfural, preferably with acidulation, is accomplished in a counterflow or countercurrent flow heat exchanger and a reactor, preferably a tubular reactor. The hydrolysate which has additionally been heated and converted in the reactor is used as a heating medium or heat carrier for heating up the hydrolysate which is converted in the counterflow heat exchanger, whereupon there is recovered as the distillate furfural in conjunction with the formic acid, acetic acid and the like.

Abstract: A method is disclosed for preventing the condensation of aluminum chloride (AlCl.sub.3) in a fractional distillation column which is operated to separate a fraction which does not include AlCl.sub.3 from a mixture containing AlCl.sub.3 and other metal chlorides and which is operated at temperatures which include the sublimation or melting points of AlCl.sub.3 at the operating pressure of the column. According to this method, titanium tetrachloride (TiCl.sub.4) is maintained in the column in an amount at least as great, by weight, as the amount of AlCl.sub.3 contained in the mixture.

Abstract: A method of separating acids or bases from vapors which are conveyed along with distillation vapors during concentration of a solution, comprising, passing said distillation vapors containing an acid or base, while being maintained at their existing pressure and temperature, through a salt solution which boils at said temperature and pressure, wherein, if an acid is to be removed from the distillation vapors, the salt solution contains a salt having an anion corresponding to that of the acid while being supplied with a base in an amount required to neutralize the acid, the cation of the base proportion corresponding to that of the salt, while, if a base is to be removed from the distillation vapors, the salt solution contains a salt having a cation corresponding to that of the base while being supplied with an acid in an amount required to neutralize the base in the distillation vapors, the anion of the acid corresponding to that of the salt so that salts are formed during neutralization which correspond to t

Abstract: Color-forming materials or their precursors present in crude 1,4-butanediol are reduced more efficiently by subjecting the crude 1,4-butanediol to distillation under conditions wherein substantially all the water present in the crude 1,4-butanediol is first removed and then the 1,4-butanediol with reduced water content is further distilled to remove the color-forming materials.

Abstract: Substantially anhydrous, i.e., absolute, ethanol is distilled at high thermal efficiency from a dilute feedstock such as a fermentate ("beer") containing one or more low boiling components whose removal at least in part prior to anhydrous distillation is necessary in order to achieve an acceptable degree of phase separation in a decanter. Most of the low boiling component(s) are removed from the feed in a rectifying column with the balance of the low boiling component(s), insufficient in amount to seriously interfere with proper operation of the decanter, being removed from the system employing a light-ends column. Both the anhydrous column and the light-ends column are operated at substantially superatmospheric pressure with thermal values recovered from these columns being used in the operation of the rectifying column.

Abstract: A process is disclosed for the recovery of a phenol-free cumene fraction from a mixture thereof with phenol and water. Said mixture is introduced into a first fractionation column at conditions to separate a bottom fraction comprising a major portion of said phenol and an overhead fraction comprising said cumene and water and a residual portion of said phenol. The overhead fraction is condensed to form an aqueous phase containing a minor portion of the residual phenol and a water-saturated organic phase comprising cumene and the balance of said residual phenol. The water-saturated organic phase is then further treated in a second fractionation column whereby cumene is recovered as an overhead fraction substantially free of phenol.

Abstract: Crude acetonitrile is purifed to 99+ weight percent by a continuous distillation procedure.

Abstract: A process for the isolation of hydroquinone, pyrocatechol, phenol and carboxylic acid from the reaction mixture containing the same such as one obtained by reaction of phenol with percarboxylic acid is disclosed. The reaction mixture is fed to a first rectification column and subjected to distillation whereby there is obtained a bottoms product containing pyrocatechol, hydroquinone and phenol. The top product is largely condensed and recycled, there being withdrawn from the top of the rectification column a mixture comprising phenol and carboxylic acid. The phenol and carboxylic acid mixture are continuously fed to a second rectification column where carboxylic acid is separated from phenol and substantially pure phenol is withdrawn from the stripping section and/or bottom of the second rectification column.

Abstract: Metal chlorides such as aluminum chloride (AlCl.sub.3) are separated from a mixture containing metal chlorides including AlCl.sub.3 and ferric chloride (FeCl.sub.3). In order to effect this separation, the mixture is subjected to a fractional distillation process utilizing an array of distillation columns. According to this process, the mixture is introduced into a first distillation column which is operated at temperatures and pressures sufficient to separate FeCl.sub.3 from the mixture while avoiding the formation of a solid solution of FeCl.sub.3 and AlCl.sub.3 within the column. At least one additional distillation column is then employed to separate metal chlorides from the remaining mixture from the first column.

Abstract: Sulfur compounds are separated from aqueous mixtures containing same by employing a stripper having at least two stripping sections with at least a portion of the stripper kettle product being recycled to the lower stripping section. The process is particularly effective in recovering mercaptans from steam condensate. In the production of mercaptans by reacting hydrogen sulfide with olefins, steam condensate contaminated with mercaptans is obtained from the steam ejector employed in the product fractionation column.

Abstract: Acetaldehyde oxime, a commercially useful intermediate in the production of pesticides, is prepared by oximating acetaldehyde with an aqueous hydroxylamine-containing solution to form an aqueous oximation reaction mixture and recovering acetaldehyde oxime from the aqueous oximation reaction mixture by distilling a mixture of acetaldehyde oxime and water directly from the aqueous oximation reaction mixture.

Abstract: A process for distilling ammoniacal solutions is disclosed comprising the utilization of two distillation columns operating at different pressures, the ammoniacal solution to be distilled being sent--after being mixed with the ammoniacal vapors flowing from the top of the column operating at the lower pressure--to the column operating at the higher pressure, from the bottom of which the partially distilled ammoniacal solution is sent to the column operating at the lower pressure; the liquid ammonia being recovered at the top of the column operating at the higher pressure while the residual ammoniacal solution is withdrawn from the bottom of the column operating at the lower pressure.

Abstract: A process for the production of alcohol from a fermented feed wherein insoluble organic matter is separated prior to entry into a first distillation column. The insoluble organic matter is dried under pressure to produce dried distillers grain and wherein excess vapor is removed from the drying zone to provide heat to the distillation system. The present process also includes removing excess water vapor from the evaporation zone, obtained from supplemental heating supplied by the overhead from said first distillation column, compressing said water vapor, and recycling it to the distillation columns and the evaporation zone.

Abstract: Process for purifying crude ethanol, whether produced by fermentation or by the synthetic route, to produce a pure ethanol-water azeotrope. The process uses only two distillation columns for fermentation ethanol and only three columns for synthetic ethanol because the latter has diethyl ether as impurity. The inventive concept lies in the design and specification of the columns and the specific distillation conditions which enable each of the impurities in ethanol to be reduced below 1 ppm. Ethanol of such purity is most desirable when used for potable or pharmaceutical purposes. The crude ethanol is fed into a first column and water is separately fed there as well, a side stream of purified aqueous ethanol is withdrawn from the first column and fed to a rectification column where a substantially pure ethanol-water azeotrope is withdrawn as a side stream. The points of introduction and removal of the respective streams to and from the columns are critical for a successful operation and product recovery.

Abstract: An improved process of distilling a cyclohexanone-rich overhead stream in a first still from a feed mixture comprising cyclohexanone, phenol and cyclohexanol of the type wherein a cyclohexanone-rich stream is withdrawn as a part of an overheads condensate from the first still and a phenol-rich stream is withdrawn as a part of a reboiled bottom stream from the first still. The improvement includes withdrawing a side stream substantially free of phenol from above the point where the feed mixture is fed to the first column and separating the side stream in a second still into a second cyclohexanone-rich overhead stream and a bottom stream containing cyclohexanone and cyclohexanol. The second cyclohexanone-rich stream may be returned to the first still.

Abstract: The recovery of alcohol from fermentation liquors is accomplished by the evaporation of the liquor feed and simultaneous rectification of the volatile component. Evaporation of the liquor feed can be accomplished by a single flash evaporation or multiple effect evaporation combined with the flash evaporation in which the flash evaporator is one effect of the multiple effect evaporator. A concentrated alcohol component is recovered along with a concentrated residue useful as a fertilizer or animal feed supplement.

Abstract: Process for isolating methyl tert-butyl ether contained in the reaction product of methanol with a C.sub.4 hydrocarbon cut containing isobutene, comprising fractionating said reaction product by introducing it at an intermediate point of a distillation zone, recovering methyl tert-butyl ether at the bottom thereof and, at the top thereof, a mixture of C.sub.4 hydrocarbons with methanol which is washed with water and condensed and wherefrom is separated a condensed C.sub.4 hydrocarbon fraction, a portion of which is fed back as reflux to the top of the distillation zone and another portion discharged, and separating the remaining water-methanol mixture by distillation.

Abstract: Formic acid is produced in a continuous process by hydrolyzing methyl formate with water at high temperature and pressure in the presence of a formic acid catalyst. Methanol is also formed. The reesterification of the reaction products to methyl formate (a reaction favored by high temperatures) is minimized by flashing the reaction product at relatively low pressure and temperature and thereafter distilling the residual liquid under vacuum. This procedure separates the methyl alcohol from the formic acid with a minimum contact time and at a low temperature which does not favor the reesterification reaction. The flashed vapor, primarily unreacted methyl formate, is recycled to the reaction zone. High purity formic acid, i.e., 85%, is obtained by subjecting the bottom from the vacuum distillation to a second distillation step. The distillate from the vacuum distillation is distilled to separate residual methyl formate for recycle from the co-product methyl alcohol.

Abstract: A process for recovering pure benzene from hydrocarbon mixtures containing the same and non-aromatic compounds which are gaseous and difficultly condensible is described in which the feedstock is fed to an initial distillation column operated at atmospheric or sub-atmospheric pressure. Overhead comprising benzene and non-aromatics is obtained and a portion thereof condensed. The condensible material is in part returned to the distillation column and in part subjected to extractive distillation to recover pure benzene. Those components which did not condense, i.e. the non-condensible and difficultly condensible components and entrained aromatics are fed to a reflux vessel such as a scrubber, stripper, or the like for recovery of any benzene or other valuable components which might be soluble in a selective solvent and used for such recovery. The selective solvent can be the same solvent used for the extractive distillation.

Abstract: A process of recovering an n-hexane product which is free from aromatic compounds by extractive distillation from a mixture of aromatic and non-aromatic compounds. The mixture is fed to and distilled in a first distillation column, from which a benzene-containing sump product and the overhead product consisting of non-aromatic compounds are withdrawn. The distillate is laterally withdrawn above the feeding point of the feed mixture and transferred to the upper portion of a second distillation column. The hexane cut is withdrawn as sump product from the second distillation column and fed to an extractive distillation column approximately in the middle thereof and is extracted in the extractive distillation column with a selective solvent which is fed above the feeding point of the hexane cut consisting of the sump product of the second distillation column. The sump product containing the selective solvent is withdrawn from the extractive distillation column and the overhead thereof vapors are condensed.

Abstract: A continuous distillation apparatus and method, the apparatus including separate stripping and rectifying sections in tandem, each of which are segregated into a plurality of vapor/liquid contact stages. The rectifying section is operated at a higher temperature than the stripping section by compressing vapor from the stripping section prior to introducing the vapor into the rectifying section. Thermal energy is conserved during the distillation process by transferring thermal energy from the rectifying section to the stripping section with a plurality of heat pipes.

Abstract: The recovery of a hydrocarbon capable of autopolymerization from an air stream by absorbing the hydrocarbon with a plasticizer and separating the hydrocarbon from the plasticizer by vacuum and atmospheric distillation.

Abstract: Acrylic acid is separated from its solutions in tri-n-butyl phosphate by establishing from such a solution a vapor phase comprising substantially all of the acrylic acid and a portion of the solvent, at a temperature below the degradation point of the acrylic acid; next partially or totally condensing said vapor phase; and then distilling the acrylic acid from such condensation product, while maintaining an amount of acrylic acid at the base of the distillation column, and conducting the distillation under conditions such that neither solvent degradation nor acrylic acid crystallization results.

Abstract: The instant invention is directed to a process for the production of diisocyanatodiphenyl methane isomers having an adjusted content of chlorine compounds comprising:(a) separating diisocyanatodiphenyl methane isomers from a polyisocyanate mixture of the diphenyl methane series in a first distillation stage,(b) subjecting said separated isomers to a second distillation stage using a recycle ratio of from 0.1 to 10 and wherein from 0.5 to 10% by weight of the feed into said second distillation stage is run off as the sump product,(c) subjecting the head product of said second distillation stage to a third distillation stage whereby readily volatile impurities are freed therefrom, and(d) working up the sump product of said third distillation stage to obtain purified 4,4'-diisocyanatodiphenyl methane and, optionally, purified 2,4'-diisocyanatodiphenyl methane.

Abstract: Crude phenol is recovered from CHP reaction products by continuously feeding to a main column separating in its uppermost section phenol from crude acetone, this fraction being removed overhead, and in the lower section crude phenol from higher boilers, including acetophenone and carbinol, the crude phenol being removed as a sidestream fraction from the main column at a point in the column above the feed-point wherein the total concentration of acetophenone plus carbinol is less than 1,000 ppm and the higher boiling compounds being removed as a base fraction.

Abstract: Butadiene is recovered from a hydrocarbon fraction containing it together with butenes and acetylene hydrocarbons by introducing said fraction into a first extractive distillation column, feeding aqueous acetonitrile into said column above the introduction point of said fraction and extracting a vapor stream containing butadiene below said introduction point; feeding said vapor stream into a second extractive distillation column, feeding aqueous acetonitrile above the introduction point of said vapor stream and recovering a vapor stream consisting essentially of butadiene at the top of said second column; and rectifying this last vapor stream to recover pure butadiene.

Abstract: A stream containing at least one noncondensible, under ordinary pressure and temperature, component and at least two components which are condensible under ordinary pressure and temperature are separated by subjecting said stream to successive fractional distillation conditions to successively remove highest boiling components. An overhead produced in one fractional distillation zone is introduced as a feed into the next fractional distillation zone. The penultimate overhead comprising only the noncondensible and a lowest boiling condensible component is partially condensed. The liquid phase is introduced onto the top tray of a last fractionation zone and the vapor phase is introduced below the top tray. A vapor stream containing a single condensible component and at least one noncondensible can be separated in the same manner as the penultimate overhead of a multi-component mixture.

Abstract: Process for the separation of trioxane from aqueous solutions containing it together with formaldehyde, which comprises subjecting the said solutions to evaporation at temperatures of 100.degree. C or lower, at pressures lower than atmospheric, and with residence times of less than 1 minute under the evaporation conditions, with vaporization of a quantity of from about 5 to about 15% by weight of the solution introduced, and recovering the trioxane from the products evaporated in this way.

Abstract: A process for the recovery of methacrylic acid from an aqueous effluent obtained by the vapor phase condensation of formaldehyde and propionic acid, where the effluent further contains unreacted formaldehyde and unreacted propionic acid, and where the recovery steps include: extracting the effluent with an organic solvent capable of azeotroping with propionic acid to obtain an organic phase and an aqueous raffinate; distilling the organic phase to remove 50-100% of the unreacted propionic acid and leaving as bottoms remaining unreacted propionic acid and methacrylic acid; distilling the methacrylic/propionic acid bottoms to obtain remaining unreacted propionic acid overhead and pure methacrylic acid as bottoms; distilling the aqueous raffinate with an entrainer to obtain dilute aqueous formaldehyde overhead and about 50% aqueous formaldehyde as bottoms; and distilling the dilute aqueous formaldehyde taken overhead to concentrate it to about 35% aqueous concentration.

Abstract: An improvement is described on a process for recovery of butadiene from a C.sub.4 hydrocarbon mixture additionally containing minor amounts of C.sub.5 saturated and unsaturated hydrocarbons, said hydrocarbon mixture being obtained as the overhead product of an initial hydrocarbon fractionation employed to separate larger quantities of C.sub.5 and heavier hydrocarbons from the hydrocarbon mixture, wherein the hydrocarbon mixture is subject to extractive distillation in the presence of a polar solvent e.g. acetonitrile, in which butadiene is separated from the fat solvent bottoms of extractive distillation by sequential low pressure flashing and stripping, followed by compression of the combined vapors of flashing and stripping with part of the compressed vapors being recycled as reboiled vapor to the extractive distillation and the remainder being again stripped at a higher pressure to recover butadiene therefrom. In this improved process, butadiene purification problems associated with carry over of C.sub.

Abstract: A process for the recovery of methylglyoxal acetal from a reaction mixture which has been obtained in the reaction of acetone with an alcohol and a nitrosation agent or oxidizing agent in the presence of an acid catalyst followed by neutralization which comprises diluting the neutralized reaction mixture with such an amount of water that a homogeneous solution is formed, subsequent distillation in a first column in which a mixture of acetone, alcohol and solvent is removed overhead and returned direct to the synthesis and an azeotrope of methylglyoxal acetal, water and high-boilers is withdrawn as a side stream, condensation of the azeotrope thus obtained and separation of the phase rich in methylglyoxal acetal, subsequent distillation of the phase rich in methylglyoxal acetal thus obtained in a second column in which purified methylglyoxal acetal is withdrawn as a side stream and the overhead and bottoms products are returned with the feed to the first column, pure methylglyoxal acetal being obtained as the

Abstract: Crude phosphate ester products resulting from the phosphorylation of phenol, lower alkyl phenols and mixtures of same are purified to prepare triaryl phosphates substantially free of unreacted phenols by the sequential steps of flash distillation and fractional distillation under controlled conditions with removal of the phosphate ester product as a liquid underflow.