Abstract: Relatively dry hydrogen iodide can be recovered from a mixture of HI, I.sub.2 and H.sub.2 O. After the composition of the mixture is adjusted so that the amounts of H.sub.2 O and I.sub.2 do not exceed certain maximum limits, subjection of the mixture to superatmospheric pressure in an amount equal to about the vapor pressure of HI at the temperature in question causes distinct liquid phases to appear. One of the liquid phases contains HI and not more than about 1 weight percent water. Often the adjustment in the composition will include the step of vaporization, and the distinct layers appear following the increase in pressure of the vapor mixture. Adjustment in the composition may also include the addition of an extraction agent, such as H.sub.3 PO.sub.4, and even though the adjusted composition mixture contains a significant amount of such an agent, the creation of the distinct liquid phases is not adversely affected.

Abstract: This invention provides a process for recovery of sodium formate from an aqueous waste stream which is a byproduct mother liquor derived from a reaction system in which pentaerythritol is produced by the reaction of formaldehyde with acetaldehyde in the presence of sodium hydroxide catalyst.As one of its important features, the invention process involves contacting the mother liquor with a monoalkylamine solvent which is highly selective for extraction of organic materials to the exclusion of sodium formate.

Abstract: A process for purifying caprolactame by continuous and/or discontinuous (or atch) vacuum distillation comprises a first stage fast vacuum distillation of the raw caprolactame possibly in the presence of an alkaline and/or alkaline-earth hydroxide, a second stage consisting of a vacuum rectification distillation of the caprolactame obtained in the first stage and a third stage consisting of the fast vacuum distillation of the caprolactame yielded from the second stage, in the presence of an alkaline and/or alkaline-earth hydroxide. The hydroxide amount in the third and possibly the first stage distillation as well varies from 0.05 to 5% preferably from 0.1% to 1%.

Abstract: A steam stripping process particularly useful for separating the volatile components of immiscible materials. In the disclosed embodiment of the invention peel oil emulsion, e.g., from a citrus juice extractor, is heated under pressure by the injection of steam while the emulsion is flowing. The major portion of the pressure on the flowing emulsion is then dropped through a back pressure valve, and the resultant vapor-liquid mixture is passed through a long turbulent passage under a slowly decreasing pressure where thorough mixing is provided and d-limonene, the volatile component of the peel oil emulsion, is stripped from the emulsion by the ad-mixed steam. The mixture is discharged at atmospheric pressure into a vapor collecting tank where the spent liquor is separated and drained off. The collected vapors are passed to a condenser, and the condensate therefrom is directed to a decant tank where the d-limonene is decanted off.

Abstract: A high melting, high boiling organic compound is easily and stably purified by continuously supplying the molten organic compound to a rectification zone under a subatmospheric pressure and continuously distilling off and recovering vapors from the top of the rectification zone, while continuously withdrawing bottoms containing higher boiling impurities and/or involatile impurities than the desired compound from a reboiling zone at the bottom of the rectification zone to the outside of rectification system by means of a barometric leg, without any pretreatment of removing lower boiling impurities therefrom before the rectification, and without disturbing a pressure balance in the rectification system.

Abstract: The invention relates to a system for purifying salty or brackish water which may, also, contain solids and living organisms making the water unpalatable for agriculture or long term animal consumption. The system includes a cyclic mechanism which causes an evaporable liquid to boil at a predetermined pressure and temperature in a first vertical elongated column, vapor cross over means to a second vertical elongated column, said vapor being condensed at a predetermined pressure and temperature in the second vertical elongated column, means for supplying heat to the first column, heat rejection means for the second column for reliquefying the material. Heat may be supplied to the first column by low temperature geothermal heat, heat from solar ponds, heat from solar collecting devices, as well as heat from the ambient air, or any form of low temperature heat for vaporizing the subject liquid.

Abstract: A process is described for the isolation of pyrocatechol and hydroquinone from mixtures containing the same, and phenol and higher boiling accompanying substances. The mixture can be one obtained by reacting phenol with a peroxidic hydroxylating agent and removing some of the phenol and the substances which have a lower boiling point than phenol. The mixture is subjected to a first rectification in which phenol and substances which have a boiling point between phenol and pyrocatechol are obtained overhead to leave behind a bottom product containing pyrocatechol and hydroquinone. The bottom product is subjected to a second rectification in which the pyrocatechol is obtained overhead to leave behind a bottom product containing hydroquinone and higher boiling accompanying substances. This bottom product is fed to a concentrating unit in which hydroquinone is evaporated overhead to leave behind high boiling accompanying substances as residue.

Abstract: Crude acetonitrile containing impurities such as hydrogen cyanide, allyl alcohol, oxazole and water is purified by at least one of the following processes (i) through (iv). (i) Process of removing hydrogen cyanide wherein crude acetonitrile is treated with an alkali in an amount sufficient to convert a substantial part of the free hydrogen cyanide present in the crude acetonitrile to an alkali metal cyanide but insufficient to convert a substantial part of the combined hydrogen cyanide present in the crude acetonitrile to an alkali metal cyanide; and then, the so obtained reaction mixture is subjected to distillation under reduced pressure.

Abstract: A normally liquid hydrocarbon having a minimum boiling point of about 425.degree. F. is utilized to provide the liquid seal in a vacuum pump which intakes a gaseous light ends stream resulting from a process for the production of ethyl acrylate by the reaction of ethylene with acrylic acid in the presence of a sulfuric acid catalyst. Upon contact in the vacuum pump, the gaseous light ends are partially absorbed into the normally liquid hydrocarbon, with the normally liquid hydrocarbon being recovered by fractionation.

Abstract: Wheat germ oil is treated by degumming with phosphoric acid and water, bleaching with activated clay and distilled in a centrifugal molecular still at 140.degree.-200.degree. C. at pressures below 50 milli-torr. The free fatty acids which are removed by the distillation step may be recovered as valuable by-products. The phospholipids removed in the degumming step may be recovered as valuable by-products. A vitamin E concentrate may be prepared by further distilling the purified wheat germ oil at 220.degree.-300.degree. C. at pressures below 25 milli-torr.

Abstract: Hydroformylation mediums, and a process for producing same, which are derived from a rhodium complex concentrate, as well as a hydroformylation process for producing aldehydes which employs said concentrate as a source of rhodium for the rhodium complex catalyst of said process.

Abstract: The decomposition of chlorinated phenols, especially pentachlorophenol, during exposure to high temperatures (e.g., storage and distillation) is markedly reduced by incorporating into the molten chlorinated phenol at least about 0.25 percent by weight of said impure chlorinated phenol of at least one monohydric primary alcohol having at least 14 carbon atoms, one hydroxyl group, and devoid of any other heteroatoms or ether linkages; selected from the group consisting of straight-chain or branched monohydric primary alcohols or a mixture of said straight-chain or branched monohydric primary alcohols.

Abstract: 2,2-Dichloro-5-methyl-1,1,1-trifluorohex-4-ene, an intermediate in the synthesis of pyrethroid insecticides, is obtained by continuous distillation, preferably under sub-atmospheric pressure, of a mixture of 5-methyl-2,2,4-trichloro-1,1,1-trifluorohexane, dimethylformamide and lithium bromide, precipitating the chlorofluorocarbons from the distillate with water and separating the desired product from starting material by a further distillation.

Abstract: In preparing a solvent-polymer mixture for a subsequent reaction, e.g., metallation, wherein undesirable components lower boiling than the solvent, such as water, should be removed from the solvent and polymer, the undesirable components are removed by stripping using previously purified solvent, thereby preventing reboiler fouling. The stripping vapors are generated from solvent obtained from a source other than the fractionation column in which the stripping occurs in order to reduce costs. The process of this invention is particularly useful in removing water from a butadiene/styrene copolymer-cyclohexane solvent mixture prior to metallation of the copolymer.

Abstract: Liquid treating apparatus especially useful for water purification, including an output section and an input section interconnected at their tops by a closed condensation chamber. The input section includes raw liquid supply and return columns, opening at their bottoms into a raw liquid supply open to the atmosphere, and the output section includes treated liquid supply and return columns open at their bottoms into a treated liquid container also open to the atmosphere.Treated liquid is cooled and circulated in the output section to produce and maintain negative pressure at one end of the condensation chamber, and raw water in mixed liquid and vapor form is supplied by aspiration in the input section, the vapor phase passing through the condensation chamber, and the liquid phase being used to drive the pump which causes the circulation in the output section. Several embodiments of the invention are shown.

Abstract: Method of removing organic contaminants from aqueous hydrochloric acid comprising countercurrently contacting the aqueous acid containing the contaminants and steam at superatmospheric pressures, and recovering said aqueous acid substantially free from organic contaminants. The invention is particularly adapted for the removal of chloral from aqueous hydrochloric acid.

Abstract: This invention describes a method for thermally stabilizing sterols to permit economic recovery of the sterols present in a sterol containing source material.

Abstract: A crude naphthoquinone produced by an oxidation of naphthalene is purified by a reduced pressure distillation of a crude 1,4-naphthoquinone having an acid content of less than 5 equivalent % calculated as monobasic acid and the crude naphthoquinone is preferably treated by an oxidation of oxidizable impurities.

Abstract: In an apparatus for distilling liquids an improvement is provided wherein distillate is heated within an auxiliary reboiler for further removal of volatile impurities, with the operating environment of the auxiliary reboiler being isolated from the main ambient atmosphere of the apparatus so that evaporated impurities can be vented without recontaminating the distillate or impairing the efficiency of the apparatus. Countercurrent flow of distillate and vapors within the auxiliary reboiler produces enhanced purity of the distillate.

Abstract: Process for the separation of a mixture of chloroacetyl chloride and dichloroacetyl chloride by extractive distillation. The mixture of chloroacetyl chloride and dichloroacetyl chloride is treated with n-dodecane, which is a saturated aliphatic hydrocarbon extraction agent. Lower levels of dichloroacetyl chloride contaminant are achieved than by prior art processes.

Abstract: A process for reclaiming a photographic coupler from an aqueous oil-in-water emulsion of a coupler solvent oil having an oil-soluble photographic coupler dissolved therein comprising separating the coupler solvent oil containing the photographic coupler dissolved therein from the aqueous oil-in-water emulsion, and subjecting the separated coupler solvent oil containing the photographic coupler dissolved therein to a high vacuum molecular distillation whereby only the coupler solvent oil is removed as a distillate.

Abstract: Volatile reactants are heated under reflux in a reactor and form volatile reaction by-products which are continuously removed in a vapor effluent from a reflux column and partial condenser. The effluent, which entrains some of the reactants, is condensed in a first total condenser and is fed to a distillation apparatus for separation of the volatile reactants and by-products and return of the separated reactants to the reactor. Before the condensate reaches the distillation apparatus, it is temporarily stored in a receiver from which it is controllably fed to a pre-heater where it is evaporated and then fed as a vapor to the distillation column of the distillation apparatus for separation. The distillation column includes at one end a reboiler which retains the reactants. The other end of the distillation column is coupled to a second total condenser in which the volatile by-products are condensed and withdrawn through a cooler for disposal.

Abstract: This invention relates to an improved process for the separation and isolation of coffee aroma constituents from roasted coffee, combining the aroma constituents with an edible substance and subsequently incorporating the aromatized substance in a food product.The process involves improving the condensation of vapors generated from the distillation of coffee oil by condensing the distilled aroma constituents onto a sleeve cooled by and snugly surrounding a container filled with coolant. The sleeve is removed and the aroma constituents condensed thereon are then preferably combined with an edible substance by manipulating the condensed constituents quickly and efficiently thus minimizing aroma loss and degradation caused by undesirable prolonged contact with air.

Abstract: Disclosed herein is a process for recovering a phosphate ester type hydraulic fluid from a waste liquid containing water, organic solvents and other impurities, such as polychlorinated biphenyls (PCB). After filtering to remove particulate matter, a heavy fraction separated from the waste liquid and consisting primarily of the hydraulic fluid is first subjected to a distillation step. A substantial portion of the PCB is removed as overhead from the distillation step and the bottoms containing the hydraulic fluid is subsequently evaporated, preferably in a thin film evaporator. The overhead from the evaporation step is condensed to recover the hydraulic fluid.

Abstract: Process for the preparation of pure methyl tert.-butyl ether. Isobutene or isobutene-containing hydrocarbon mixtures are reacted with methanol in a molar ratio of 1:1 to 1:2 in the liquid phase at temperatures of between 30.degree. and 100.degree. C. on sulfonated, strongly acidic, macroporous organic ion exchange resins. After separation of the unreacted hydrocarbons, the reaction mixture is distilled under pressure; the methanol-containing distillate formed during the distillation is recycled into the zone of the reaction between methanol and isobutene; and pure methyl tert.-butyl ether is withdrawn from the sump of the distillation column.

Abstract: A process for the continuous and automatic separation of toluene diisocyanate, without decomposition, from distillation residues comprising evaporating toluene diisocyanate in an agitated, scraped evaporator, under a vacuum of about 1 mm Hg to about 50 mm Hg and at a temperature of about 210.degree. C. to about 250.degree. C., with a minimum residence time, preferably about 15 minutes, in an evaporator, and continuously extracting the remaining components of the residue.

Abstract: Tall oil containing anthraquinone is fractionally distilled for producing the tall oil heads cut enriched in said anthraquinone.

Abstract: A dehydrating purification process for a fermentation product, which comprises adding at least one polyhydric alcohol represented by the formulae (III) or (IV), ##STR1## wherein R.sub.8 represents a hydrogen atom or a methyl group, R.sub.9 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and m and n represent integers from 1 to 6, to hydrated Sophorolipid or a secondary derivative thereof which is a fermentation product of Torulopsis bombicola, and distilling off water with heating under reduced pressure.

Abstract: Alkane dicarboxylic acids of at least 4 carbon atoms particularly the mixture of succinic, glutaric and adipic acids obtained as byproduct in the manufacture of adipic acid are purified by co-distillation with an alkylbenzene having an atmospheric pressure boiling point of 300.degree. to 350.degree. C. especially dodecylbenzene.

Abstract: According to the present invention an impure liquid containing ethylene glycol or propylene glycol, lower carboxylate esters of the glycol, water, carboxylic acid and glycol-azeotroping agent is treated for removal of substantially all of said glycol-azeotroping agent by a process which comprises distilling the impure liquid in a distillation zone to form an overheads product comprising water and glycol-azeotroping agent and a bottoms product comprising the glycol, esters and carboxylic acid, which is substantially free of said glycol-azeotroping agent, said bottoms product containing water in an amount of at least about 1 weight percent of the amount of water passed to said distillation zone with said impure liquid.

Abstract: A method and apparatus is disclosed for the distillation of readily polymerizable vinyl aromatic compounds with polymerization inhibitors of low volatility, particularly a phenothiazine (PZ)-tertiarybutylcatechol (TBC) polymerization inhibitor combination. The method comprises introducing a feed of impure vinyl aromatic compound into a typical distillation train comprising a first fractionation column, a recycle column, and a finishing column; introducing as a separate stream into the upper portion of said recycle column and into said first fractionation column an effective amount of the PZ-TBC inhibitor in a volatile aromatic hydrocarbon diluent; and then distilling the vinyl aromatic compound in the presence of oxygen to recover an overhead product of high purity vinyl aromatic compound and a bottoms fraction.

Abstract: A method for purifying benzotriazole, tolyl-triazole or mixtures of the two is disclosed. The method includes the steps of vacuum distillation of crude triazole and collection of the condensate. The crude triazole contains color bodies, diazotizable impurities which are color body precursors, or both. The color of the distilled triazole is improved by adding to the crude triazole, prior to vacuum distillation, an amount of formaldehyde sufficient for reaction with an appreciable proportion of the color bodies, the color body precursors, or both.

Abstract: A method for separating an aqueous solution which contains minor amounts of nitrated esters which are only slightly soluble in water is provided. Separation of the nitrated esters, which include ethylene glycol dinitrate and nitroglycerin, is effected by contacting the aqueous solution with an organic phase of ethylene glycol dinitrate for a period of time sufficient to allow extraction of the nitroglycerin in solution into the ethylene glycol dinitrate phase. The organic ethylene glycol dinitrate phase is then separated from the aqueous solution, and the latter is distilled at a temperature of from about 50 degrees F. to about 200 degrees F. at a lower than atmospheric pressure. Upon completion of the separation process water, which is substantially free of nitrated esters, is suitable for discharge and return to a natural environment.

Abstract: A process for concentrating at least one of (a) individual halogenoanthraquinones (b) binary mixtures of di-halogenoanthraquinones and (c) binary mixtures of trihalogenoanthraquinones, from a mixture containing at least two halogenoanthraquinones, comprising subjecting said mixture containing at least two halogenoanthraquinones to fractional vacuum distillation in a heated rectification column having an efficiency corresponding to about 20 to 50 theoretical stages with an absolute pressure at the top of about 0.5 to 50 mm Hg and a reflux to take-off ratio of about 5/1 to 50/1.

Abstract: A unique combination of specially chosen entrainers, e.g., pentanes and cyclohexane, and high-pressure azeotropic distillation conditions, e.g., 100-200 psig., provides an economically efficient separation of a C.sub.2 -C.sub.5 alkyl alcohol, e.g., isopropanol, from its aqueous mixture; and also results in the production of a useable steam having a sufficient pressure, e.g., from 10 psig. to 30 psig. Preferably, said azeotropic distillation is conducted in the substantial absence of oxygen, e.g., less than 1 wppm.

Abstract: In an oxidation process for converting methacrolein to methacrylic acid, methacrylic acid is recovered by cooling and condensing the effluent from the oxidation, followed by azeotropic distillation of the condensate with a suitable solvent, such as methyl n-propyl ketone. The condensed effluent contains methacrylic acid and water as the major components along with by-product acetic acid, a minor amount of unreacted methacrolein and impurities. Substantially dry crude methacrylic acid is separated as a bottom product from the azeotropic distillation and an azeotrope of water and the solvent is taken overhead and condensed. After condensation, solvent-rich and water-rich phases form and are separated. The solvent-rich phase is returned to the distillation column as a reflux, while the water-rich phase is sent to a stripping column for recovery of residual solvent. Water is withdrawn from the bottom of the stripping column and recycled or discarded, as desired.

Abstract: A method for purifying a liquid by vacuum-induced vaporization of the impure liquid into a vapor in a first enclosure and subsequent pressure-induced condensation of the vapor into a relatively pure liquid in a second enclosure. A conduit interconnecting the two enclosures includes a pressure-sensitive one-way valve for permitting automatic pressure-induced vapor flow from the first enclosure to the second enclosure while preventing vapor flow in the opposite or return direction. In a first embodiment, the alternating pressure variation necessary to produce the vaporization in the first enclosure, the vapor flow through the conduit and the condensation in the second enclosure is produced by exposing the interiors of the two enclosures to the undulating motion of the surface of an open body of wave-active liquid. In a second embodiment, the alternating pressure variations are produced by mechanical means.

Abstract: Fluid mixture of acetone and at least one hydrocarbon containing four-carbon atoms is separated by fractional distillation at a pressure low enough to eliminate formation of an azeotrope and a corresponding temperature.

Abstract: A process for the continuous preparation of organic solutions of percarboxylic acids by reaction of an aqueous solution of hydrogen peroxide with the corresponding carboxylic acid in the presence of an acid, water-soluble catalyst which boils above 160.degree. C., extraction of the percarboxylic acid from the resulting reaction mixture using an organic solvent which is immiscible with water, reconcentration of the raffinate, which essentially contains hydrogen peroxide and the acid catalyst, by distilling off water in a distillation column and recycle of the raffinate, concentrated in this way, into the reaction with the carboxylic acid. The raffinate is divided into two partial streams in a ratio of 1 to 25:1.

Abstract: A process for simultaneously generating power and recovering potable water from a source of salinous water -- e.g. sea water. Salinous water, from a locus which is proximate to the surface thereof and at a relatively high temperature -- e.g. about 85.degree. F. -- is exposed to radiant solar energy to increase significantly the temperature thereof -- e.g. to a level of at least about 135.degree. F. The heated water is introduced into a plurality of flash separation zones, each succeeding one of which is maintained at a lower subatmospheric pressure than the preceding zone, to provide substantially non-salinous vaporous phases. The salinous liquid phase is introduced in series through the plurality of flash zones. The vapor phases are passed through separate, individual turbines, or are introduced into different stages of a multi-stage turbine, from the resulting motion of which power is generated.

Abstract: Crude 1,10-decanedicarboxylic acid produced by the nitric acid oxidation at 20.degree.14 60.degree. C. of cyclododecanone, cyclododecanol or a mixture thereof can be purified by distillation to a purity suitable for use in the production of polyamides and polyesters by reducing prior to distillation, e.g., by heating to 70.degree.-90.degree. C., the organically bound nitrogen content and as required the nitric acid content, e.g., by washing, and water content thereof so that the sample which is distilled has maximum contents thereof of 0.05%, 0.02% and 0.1% by weight, respectively, and distilling the pre-purified sample at a sump temperature of 215.degree.-225.degree. C. and at a pressure of 0.5 - 2 torr.

Abstract: A method for separating an aqueous solution which contains minor amounts of nitrated esters which are only slightly soluble in water is provided. Separation of the nitrated esters from the aqueous solution is effected by distilling the aqueous solution at a temperature of from about 50.degree. to about 200.degree. F and a lower than atmospheric pressure. Upon completion of the separation process, water which is substantially free of nitrated esters is suitable for discharge and return to a natural environment.

Abstract: This invention relates to the use of a heat pump in combination with a column having a low pressure loss for separating mixtures with similar boiling points in a vacuum of 10 Torr up to normal pressure. By using this arrangement,it is possible to separate isomers in particular, saving heat in relation to normal distillation.

Abstract: In a method of obtaining purified 2,6-naphthalenedicarboxylic acid dimethyl ester by vacuum distilling crude 2,6-naphthalenedicarboxylic acid dimethyl ester under conditions of application of heat, the improvement which comprises vacuum distilling a crude 2,6-naphthalenedicarboxylic acid dimethyl ester having an acid value (A.sub.f), as expressed in milligrams of KOH required for neutralizing the carboxyl groups contained in one gram of said crude 2,6-naphthalenedicarboxylic acid dimethyl ester, of from 1.0 to 50.

Abstract: A process for simultaneously generating power and recovering potable water from a source of salinous water -- e.g. sea water. Salinous water, from a locus which is proximate to the surface thereof and at a relatively high temperature -- e.g. about 85.degree. F. -- is exposed to radiant solar energy to increase significantly the temperature thereof -- e.g. to a level of at least about 135.degree. F. The heated water is introduced into a plurality of flash separation zones, each succeeding one of which is maintained at a lower subatmospheric pressure than the preceding zone, to provide substantially non-salinous vapor phases. The salinous liquid phase is introduced in series through the plurality of flash zones. The vapor phases are passed through separate, individual turbines, or into different stages of a multiple-stage turbine, from the resulting motion of which power is generated.

Abstract: A process for simultaneously generating power and recovering potable water from a source of salinous water -- e.g. sea water. Salinous water, from a locus which is proximate to the surface of the source and at a relatively high temperature -- e.g. about 85.degree. F. -- is exposed to radiant solar energy to increase significantly the temperature thereof -- e.g. to a level of at least about 135.degree. F. The heated water is introduced into a plurality of flash separation zones, each succeeding one of which is maintained at a lower subatomospheric pressure than the preceding zone, to provide substantially non-salinous vapor phases. The salinous liquid phase is introduced in series through the plurality of flash zones. The vapor phases are utilized to vaporize hydrocarbons, in separate vaporizers, and the hydrocarbon vapors are passed through separate, individual turbines, or are introduced into different stages of a multi-stage turbine, from the resulting motion of which power is generated.

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: The present invention relates to a process for inhibiting the polymerization of styrene monomers during the purification of crude styrene.

Abstract: Diepoxides of the general formula: ##STR1## wherein n has an average value not exceeding 0.03 and R is the bisphenyl radical of bisphenol-A are recovered from an epoxy resin of the same general formula with n varying from 0.07 to 0.30, by removing the low-boiling substance from the epoxy resin at 0.1-1 mm Hg and 165.degree.-200.degree. C and distilling off said diepoxide from the thus treated epoxy resin at 0.1-0.005 mm Hg and a temperature not exceeding 240.degree. C. The low viscosity, narrow molecular weight distribution and excellent purity of these diepoxides allow their use in critical application fields.