Abstract: This invention relates generally to salt forms the compound of formula I: 1

Abstract: A process for producing adipic acid is provided which comprises a step of oxidizing hydroxycaproic acid and/or &egr;-caprolactone with oxygen or oxygen-containing gas using a metal in the platinum group as a catalyst. According to the process, adipic acid is produced without using nitric acid, which becomes the main factor responsible for the by-production of nitrogen oxides, and without using any particularly high-pressure conditions.

Abstract: Compounds of the formula R2.[(AO)n.R3]m, where R2 is a residue of a group having at least m active hydrogen atoms derived from hydroxyl and/or amino and/or amido groups, AO is alkyleneoxy, n is 2 to 200; R3 includes residue(s) of alkenyl succinic acids and optionally other acids, and m is 2 to 10, but when m is 2 there are other restrictions in the definitions, are disclosed as useful thickeners and/or dispersants in aqueous systems. The use of such materials as thickeners is also disclosed.

Abstract: A method for the reduction in iodine content in a mixture, particularly in a mixture of carboxylic acids and/or carboxylic anhydrides with alkyl iodides and/or hydriodic acid, comprises contacting the organic medium in the vapor phase at elevated temperature with a metal salt dispersed on activated charcoal. The metal salt may be a carboxylate salt, a carbonate, an oxide, a hydroxide and any other salt, which may react with the organic medium to give a metal carboxylate salt. The metal may be a main group element, a lanthanide, an actinide, zinc and copper. This process converts alkyl iodide compounds converted to their corresponding carboxylate esters, while the iodine is bound in the purification mass as inorganic iodide.

Abstract: Carboxylic acids, particularly dicarboxylic acids, are separated from a fermentation broth by adjusting the pH of the fermentation broth to about 2.0 or below, and then heating the broth to a temperature sufficient to cause formation of three immiscible phases, one of which is an organic phase containing the carboxylic acids.

Abstract: The invention pertains to chiral ferrocene phosphine derivatives and their use with transition metals as asymmetric catalysts in asymmetric hydrogenation.

Abstract: The invention relates to single step process for the preparation of poly (oxyalkylene)-alpha, omega-dicarboxylic acids of the formula HO2CCH2O(CH2CHRO)nCH2CO2H, wherein R is hydrogen, methyl or mixtures of hydrogen and methyl on the individual molecule and n is an integer of from 100 to 2500, comprising the steps of reacting, an oxidising agent such as poly (oxyalkylene glycol) with Jone's reagent in a polar solvent at a temperature in the range of 10° C. to room temperature for a period ranging between 1 hour to 12 hours, quenching the reaction by adding free radical scavanger, removing oxidation by-products from reaction mixture by adsorbing them on an adsorbing agent to obtain dicarboxylic acids in the solution, and evaporating the clear solution to obtain poly (oxyalkylene)-alpha, omega-dicarboxylic acids.

Abstract: This invention relates to methods and reactor devices for controlling the oxidation of hydrocarbons to dibasic acids, in the presence of a cobalt catalyst and a monobasic acid, such as acetic acid, by treating the catalyst from the reaction mixture, outside the oxidation zone, after the oxidation has taken place at least partially. In one preferred embodiment, the catalyst is reduced to contain, preferably predominantly and more preferably substantially, cobalt ions in valence II, and at least partially precipitated by de-watering and/or thermal treatment. In a different preferred embodiment, the catalyst in the reaction mixture is first oxidized or maintained, preferably predominantly and more preferably substantially, at valence III, the reaction mixture is de-watered, the catalyst is reduced, preferably predominantly and more preferably substantially, to valence II, causing precipitation either spontaneously at a predetermined temperature or after further thermal treatment.

Abstract: The invention discloses a method for purifying adipic acid in water. More precisely it discloses an improvement in adipic acid crystallization or recrystallization in water, characterised in that the said crystallization or recrystallization is effected in presence of a strong proton acid and/or in the presence of carbon monoxide. This crystallization or recrystallization particularly enables the content of metal catalyst traces in the adipic acid to be reduced.

Abstract: Biodegradable resin products consisting essentially of a polymeric resin of starch, polyesters of polylactic acid and polycaprolactone. In admixture with the resin is a particulate vapor phase corrosion inhibitor selected from amine salts, ammonium benzoate, triazole derivatives, tall oil imidazolines, alkali metal molybdates, alkali dibasic acid salts, and mixtures thereof, and is present in an amount ranging from between about 1% and 3% by weight of the polymeric resin.

Abstract: Electrolytic hydrodimeric coupling of dialkyl maleates in alkanol solutions containing an alkanol-soluble alkali metal acetate/quatemary ammonium tetrafluoroborate mixed supporting electrolyte yields tetraalkyl 1,2,3,4-butanetetracarboxylates.

Abstract: This invention relates to methods of removing acetic acid from cyclohexane in the direct oxidation of cyclohexane to adipic acid, especially after recycling catalyst which is precipitated by introduction of additional cyclohexane. The removal of acetic acid is preferably conducted by use of rather small amounts of wash-water in one to three stage extractors. A two stage reactor is preferable as being more efficient.

Abstract: The present invention provides water-miscible lipid derivatives effective to inhibit the infectious activity of pathogenic microorganisms. Preferred water-miscible lipid derivatives are diacetyltartaric acid esters of monoglycerides wherein 90 percent or more of the fatty acid content is accounted for by a single fatty acid. The fatty acid component preferably contains from 8 to 24 and, more preferably, from about 10 to about 20 carbon atoms. The fatty acid can be saturated, unsaturated or hydroxylated.

Abstract: Process for the treatment of a material comprising a polymer, especially a polyamide. The process consists in subjecting the polyamide to hydrolysis in the presence of a hydrolyzing nitrous grouping and transforming the hydrolyzed compounds into diacids. The treatment of a polyamide 6.6 results in the recovery of adipic acid and other diacids corresponding to the participating acid monomer and to the transformation of at least one part of the diamine monomer into diacids.

Abstract: The present invention relates to a method of processing reaction mixtures obtained from the oxidation reaction of cyclohexane to adipic acid. The processing of the reaction mixture obtained from the direct oxidation of cyclohexane to adipic acid with oxygen, in an organic solvent and in the presence of a catalyst, comprises:(a) a distillation which makes it possible to separate out, on the one hand, a distillate comprising at least some of the most volatile compounds such as the unconverted cyclohexane, the organic solvent, cyclohexanone, cyclohexanol, cyclohexyl esters, lactones and water, and, on the other hand, the distillation residue comprising the diacids formed and the catalyst;(b) the addition of water to the distillation residue in order to form an aqueous solution;(c) crystallization of the adipic acid from the aqueous solution of the distillation residue.

Abstract: Wood preservative systems comprising (a) a biocidal effective amount of (i) at least one di C.sub.8 -C.sub.12 alkyl quaternary ammonium carboxylate having the formula ##STR1## wherein R.sup.1 and R.sup.2 are a C.sub.8 -C.sub.12 alkyl group; R.sup.3 is a substituted or unsubstituted, interrupted or uninterrupted C.sub.1 -C.sub.100 group; l and q independently are 1, 2 or 3 and (l) (q) is 1, 2, or 3; and n is 0 or an integer from 1 to 50; (ii) at least one di C.sub.8 -C.sub.12 alkyl quaternary ammonium borate having the formula ##STR2## wherein R.sup.1 and R.sup.2 are defined as above, and a is 2 or 3, but when a is 2, b is 0 or 1, and when a is 3, b is 0, 1, or 2; or (iii) a combination of (i) and (ii); and (b) a solvent are provided. These carboxylate quats as well as carboxylate quats wherein R.sup.1 is a C.sub.1 -C.sub.20 alkyl or aryl-substituted alkyl group and R.sup.2 is a C.sub.8 -C.sub.20 alkyl group are preferably prepared by an indirect or a direct synthesis.

Abstract: Malonic acid and alkylmalonic acids are prepared by a process of acid-catalyzed saponification of malonic acid esters, which comprises:contacting an aqueous mixture of the ester II with an acid ion exchanger containing sulfonic acid groups at from 30.degree.-100.degree. C. and from 40-1000 mbar according to the following scheme: ##STR1## where R.sup.1 =H, CH.sub.3,R.sup.2 =H, CH.sub.3 orR.sup.1 +R.sup.2 =--CH.sub.2 --CH.sub.2 --andR.sup.3 =CH.sub.3, C.sub.2 H.sub.5, C.sub.3 H.sub.7, C(CH.sub.3).sub.3 ;distilling off the alcohol R.sup.3 OH which is formed;separating the water, with the aid of organic solvents, from the malonic acid or alkylmalonic acid product; and thenisolating the product by crystallization.

Abstract: Substantially anhydrous nylon salts are made in a solid state process in which solid diamine carbamates are contacted and mixed with solid dicarboxylic acids in a near instantaneous reaction to produce the salt, and preferably are prepared by mixing the solid diamine carbamates and the solid dicarboxylic acids under conditions of high shear.

Abstract: Alkyl- and arylmalonic acids of the formula I ##STR1## where R.sup.1 =H, C.sub.1 -C.sub.12 -alkyl, phenyl, C.sub.1 -C.sub.4 -alkylphenyl, C.sub.2 -C.sub.4 -dialkylphenyl,R.sup.2 =C.sub.1 -C.sub.12 -alkyl, phenyl, C.sub.1 -C.sub.4 -alkylphenyl, C.sub.2 -C.sub.4 -dialkylphenyl orR.sup.1 +R.sup.2 =--CH.sub.2 --CH.sub.2 --, are prepared by alkaline saponification by hydrolyzing the corresponding C.sub.1 -C.sub.4 -alkyl esters of the malonic acid of formula I, with alkali metal hydroxide dissolved in an aqueous alkali metal salt solution containing salt at 90-100% of saturation, acidifying the hydrolysis product with a mineral acid, removing the precipitated alkali metal salt which forms upon acidification, and extracting the alkyl- and arylmalonic acid formed from the aqueous solution with the aid of an organic solvent.

Abstract: Malonic acid or a salt of the same is obtained at high yield according to the invention through the catalytic oxidation with oxygen or an O.sub.2 -containing gas of 3-hydroxy propionaldehyde or 3-hydroxy propionic acid in the aqueous phase. The conversion takes place in the presence of at least 10 percent by weight, relative to the C.sub.3 building block used, of a precious metal from the platinum group. Pd and Pt supported catalysts are preferred.

Abstract: The invention provides a process for directly manufacturing a diamine/dicarboxylic acid salt with a low water content. The process includes reacting a diamine with a dicarboxylic acid to form a diamine/dicarboxylic acid salt. The reaction of the diamine and the dicarboxylic acid is carried out in the presence of about 0.5% to about 25% by weight water, based on the weight of the reaction mixture, while providing conditions in the reaction mixture such that the reaction mixture is in substantially solid particulate form.

Abstract: A process for recycling a catalyst containing cobalt including treating a reaction mixture obtained during the direct oxidation of cyclohexane to adipic acid by extracting at least some of the glutaric acid and succinic acid which are formed in the reaction.

Abstract: Process for the manufacture of xylaric acid, characterized in that it consists of the oxidative degradation of 5-ketogluconic acid in alkaline medium using oxygen or a gas containing it.The xylaric acid obtained is of use as a calcium-chelating agent or as a component of polyhydroxypolyamides or as an intermediate in the synthesis of xylitol.

Abstract: The invention relates to a process for the selective recovery of catalysts used in the production of adipic acid by(a) separating adipic acid from the reaction solution,(b) exposing the resultant reaction solution to a sulfonated ion exchanger, thereby binding iron, copper, and vanadium ions to said sulfonated ion exchanger,(c) separating the ion-exchanger from the reaction solution,(d) washing the separated ion exchanger with nitric acid to obtain an acid eluate, and(e) exposing the acid eluate to an ion exchanger modified with aminophosphonic acid groups, thereby removing the iron ions from the acid eluate.

Abstract: This invention provides a process for the preparation of adipic acid from pentenoic acids or esters of pentenoic acids by hydrocarboxylation of a reaction mixture in which gamma-valerolactone constitutes 30 to 70% by weight of the reaction mixture.

Abstract: The invention relates to malonic acid derivatives, which inhibit the binding of selectin to carbohydrate ligands, and pharmaceutical compositions and diagnostic agents containing these derivatives, and methods for using these pharmaceutical compositions and diagnostic agents.

Abstract: A dry food acidulent composition, reminiscent of vinegar when hydrated, comprises a dry food acid, a buffering salt and a fully dissociatable salt. The dry food acid preferably comprises adipic, citric, fumaric, malic acid or a mixture. The buffering salt is preferably a sodium or potassium salt of a food-grade acid such as sodium citrate, potassium citrate, disodium phosphate, dipostassium phosphate, and mixtures. The fully dissociatable salt is preferably sodium chloride or potassium chloride. The preferred weight ratio of the buffering salt to the acid is within the range of from about 0.1:1 to about 0.3:1, that of the fully dissociatable salt to the acid is within the range of from about 1:1 to about 6:1, and that of the fully dissociatable salt to the buffering salt is within the range of from about 10:1 to about 30:1. These compositions are admixed with other dry ingredients to prepare dry sauce and dressing mixes.

Abstract: Heteropolyoxometallates of tungsten, molybdenum and vanadium with a structurally defined micropore volume, a method of production by means of the hydrothermal reaction of the appropriate metal with an associated oxide, a diamine, phosphoric acid and water, and the use of the novel compounds as catalysts.

Abstract: The present invention relates to a novel glycerol derivative and a process for preparing the same, and a process for preparing a triazole derivative.According to the present invention, an optical active 2-arylglycerol derivative which is a novel and useful as a synthetic intermediate of medicament can be provided and furthermore, (R)-2-(2,4-difluorophenyl)-3-(1H-1,2,4-triazole-1-yl)-propane-1,2-diol which is useful as an antifungal agent can be prepared.

Abstract: The invention relates to novel compositions comprising ene and free radical adducts of unsaturated and saturated hydrocarbons, and acyclic and cyclic vicinal polycarbonyl compounds such as diethyl ketomalonate and indantrione. The adducts are reacted with nucleophiles such as amines, electrophiles such as anhydrides and esters, and metal ions. Post-products are obtained via reaction of said products with capping reagents such as boric acid. Compositions containing said adducts, products and post-products include oleaginous substances such as fuels and lube oils.

Abstract: This invention relates to the preparation of cesium salts from cesium-aluminum-alum in a process in which the cesium-aluminum-alum is reacted in a single vessel in the presence of water with calcium hydroxide in an amount which is equimolar to the amount of aluminum and with a readily water-soluble calcium salt in an amount which is equimolar to the amount of cesium and the precipitated aluminum hydroxide and the precipitated calcium sulfate are separated by filtration or centrifugation.

Abstract: Rapid temperature rises which characterize carbohydrate-nitric acid oxidation reactions used to form carbohydrate-derived acids may be moderated and temperature control readily maintained by blowing a gas such as air, oxygen, nitrogen or the like into the reaction mixture as needed to control the temperature of the reaction. The more moderate reaction conditions afford higher yield of the desired product with a concomitant reduction of byproducts which may be difficult to remove and usually are unwanted as well. Upon completion the oxidation mixture is made basic (e.g. with an alkali metal base hydroxide or carbonate, ammonia or an amine) to a pH at which the the carboxyl group or groups of the product carbohydrate-derived acid are entirely in the salt form. The aqueous solution is then passed through an ion retardation resin column to recover the carbohydrate-derived salt, using water as the eluent.

Abstract: Polycocondensates based on aspartic acid which are obtainable by condensing aspartic acid in the presence of polymers containing carboxyl groups, which contain at least 10 mol % of a monoethylenically unsaturated carboxylic acid in copolymerized form and have a molecular weight of at least 300, in the weight ratio from 1,000:1 to 2:1, processes for preparing the polycocondensates and use of the polycocondensates in the form of the free acid groups or in a form neutralized with ammonia, amines, alkali metal or alkaline earth metal bases as an additive to detergents and cleaners, as scale inhibitors or as dispersants for finely divided solids are described.

Abstract: The present invention relates to a process for the treatment of waste gas discharged from a cyclohexane oxidation reactor used in the manufacture of adipic acid, said waste gas containing mainly nitrogen, oxygen, carbon monoxide, carbon dioxide, acetic acid, and up to 10% by weight cyclohexane, as well as other gases or vapors, by (a) scrubbing the waste gas from the cyclohexane oxidation reactor with acetic acid in a first absorption step to reduce the amount of cyclohexane to a residual content of less than about 1% by weight, (b) scrubbing the waste gas from the first absorption step with water in a second absorption step to reduce the amount of acetic acid to a residual content of less than about 1% by weight, and (c) subjecting the scrubbed waste gas from the second absorption step to an oxidation step to oxidize carbon monoxide and other oxidizable components of the waste gas to carbon dioxide and water.

Abstract: Waste nylon 6 and/or nylon 6,6 are converted to adipic acid monomer by depolymerization with an aliphatic monocarboxylic acid to form alkylamides followed by oxidation of the alkylamides to adipic acid.

Abstract: A process for preparing adipic acid from cyclohexene oxide comprising the following steps (a) and (b):(a) hydrating cyclohexene oxide to obtain 1,2-dihydroxycyclohexane and an oligomers represented by formula (I): ##STR1## wherein n represents a number of from 1 to 5 in number average, and (b) oxidizing the 1,2-dihydroxycyclohexane and the oligomers represented by formula (I) in a nitric acid aqueous solution.

Abstract: Fumaric acid derivatives of the formula ##STR1## wherein R.sub.1 is a hydrogen atom, a C.sub.1 -C.sub.8 alkyl group or a metallic cation, andR.sub.2 is a saturated or unsaturated aliphatic C.sub.6 -C.sub.24 alkyl group, psoralen-9-yl, retinyl, .alpha.-tocopheryl (vitamin E), calciferyl, corticosteroid-21-yl or monosaccharid-.omega.-yl; a group of fumaric acid derivatives based on glycerol, alkane diol or polyol molecules; and fumaric acid derivatives of the formula ##STR2## wherein n is an integer from to 30 to 260,R.sub.3 is a hydrogen atom or a C.sub.1 -C.sub.3 alkyl group,R.sub.4 is one of the R.sub.3 groups and n is the number of molecule repetitions, processes for their production and compositions containing same are described. These compounds are useful as drugs for the treatment of cryptogenically-caused diseases and have antisporiatic as well as antimicrobial action.

Abstract: A method for making a valproic acid derivative comprising a functionalized spacer arm attached to a .delta. carbon atom of a valproic acid molecule is disclosed. The method proceeds by attaching a spacer arm joined to an inorganic moiety to a valproic acid precursor to make an alkylated compound, derivatizing the alkylated compound in a liquid medium to make the valproic acid derivative, and then separating the valproic acid derivative from the liquid medium. The valproic acid derivative can be used to make an immunoreactive valproic acid conjugate.

Abstract: Process for improving a controlled oxidation reaction between at least one reactant and oxygen, in which at least one reactant is reacted with oxygen or an oxygen containing gas, constituting a reaction mixture, in the presence of at least one additional gas which is introduced into said reaction mixture and is selected from methane, ethane and helium, and the resulting reaction product from the oxidation reaction is possibly treated so as to give a final product.

Abstract: The present invention provides new and structurally diverse compositions for diagnostic imaging comprising compounds of the general formula: ##STR1## wherein A is N or CR.sub.1, R.sub.1 is hydrogen, C.sub.1 -C.sub.8 alkyl, or C.sub.6 -C.sub.10 aryl, where the alkyl or aryl group may be optionally substituted with one or more hydroxy, C.sub.1 -C.sub.8 alkyl, C.sub.1 -C.sub.8 hydroxyalkyl, C.sub.1 -C.sub.8 alkoxy, C.sub.6 -C.sub.10 aryl, C.sub.6 -C.sub.10 hydroxyaryl, C.sub.6 -C.sub.10 aryloxy, --CO.sub.2 R.sub.2, --CONR.sub.3 R.sub.4, or NR.sub.3 R.sub.4 ; D is O, --O(CH.sub.2).sub.2 O--, --O(CH.sub.2).sub.3 O--, or NR.sub.5 ; E is O, --O(CH.sub.2).sub.2 O--, --O(CH.sub.2).sub.3 O-- or NR.sub.6 ; F is O, --O(CH.sub.2).sub.2 O--, --O(CH.sub.2).sub.3 O-- or NR.sub.7 ; R.sub.2 -R.sub.7 are as defined within; g, h, i, j, k and m may be the same or different and are an integer from one to about six; X is --CO.sub.2 H, --PO.sub.3 H.sub.2, --SO.sub.3 H or --CONHOH.

Abstract: The present invention relates to a method of reacting polyamides or mixtures thereof with ammonia to obtain a mixture of monomers. The reaction is carried out in the presence of certain Lewis Acid catalyst precursors.

Abstract: Butanetetracarboxylic acid with acceptably low levels of color-causing contaminants, suitable for permanent press agent use, is prepared in high conversion and yield from tetraalkyl butanetetracarboxylates by a series of steps including purification of precursor material, hydrolysis with high concentration of acid catalyst, and oxidative purification of product.

Abstract: An aqueous solution, for use as a cement dispersing agent, of a polymer salt, which is formed by reacting a polycarboxylic acid with a nitrogenous acrylic polymer.

Abstract: Conversion of certain lactones by reaction with carbon monoxide and water, in the presence of a homogeneous rhodium catalyst and an iodide or bromide promoter, to produce adipic acid.

Abstract: The subject matter of the invention is a process for the preparation of carboxylic acids and derivatives of them of the general formula ##STR1## wherein R means hydrogen, or a C.sub.1-4 alkyl or a (C.sub.1-5 alkoxy)carbonyl group,R.sub.1 is as defined in claim 1,R.sub.7 stands for hydrogen or a C.sub.1-7 alkyl group andR.sub.8 means hydrogen or a carboxyl group,by reacting a 1,3-dioxane-4,6-dione derivative of the general formula ##STR2## wherein R.sub.9 stands for a C.sub.1-4 alkyl group or a phenyl group, optionally monosubstituted by halogen andR.sub.10 stands for hydrogen or a C.sub.1-5 alkyl group orR.sub.9 and R.sub.10 together form a pentamethylene group,and an aldehyde or ketone of the general formula ##STR3## in the presence of formic acid.

Abstract: A method of preparing carboxylic acids or esters thereof by the oxidative cleavage of unsaturated fatty acids or esters thereof is carried out in a two-phase aqueous-organic system in which the organic phase contains the unsaturated fatty acid and/or the esters thereof and the aqueous phase contains hydrogen peroxide. The oxidative cleavage is carried out in the presence of a catalytic system including a catalyst belonging to the group constituted by tungstic and molybdic acids and alkaline salts thereof, and an onium salt which acts as a phase-transfer agent for the catalyst, and has the formula:(R.sub.2 R.sub.3 R.sub.4 R.sub.5 M).sup.+ Y.sup.-in which R.sub.2, R.sub.3, R.sub.4 and R.sub.5 represent hydrocarbon groups of which at least one must have more than 10 carbon atoms,M is N or P, andY.sup.- is an inorganic anion.

Abstract: A process for preparing an optically active carboxylic acid is disclosed, comprising asymmetric hydrogenation of an .alpha.,.beta.-unsaturated carboxylic acid using an alcohol as a hydrogen donor in the presence of a metal-optically active phosphine complex. A carboxylic acid having high optical purity can easily be obtained in a high yield without using specific equipment as required in using hydrogen gas as a hydrogen donor.

Abstract: An improved process for the production of carboxylic acids and dicarboxylic acids by the catalytic oxidation of olefins and vicinal diols by hydrogen peroxide is provided. The process employs a rhenium (VII) catalyst, and a solvent comprising a mixture of a carboxylic acid or anhydride having 2 or more carbon atoms and a high boiling cyclic or acyclic ether. Particularly suitable carboxylic acids or anhydrides include acetic acid, propionic acid and acetic anhydride. Particularly suitable high-boiling ethers include 1,4-dioxane and diglyme.

Abstract: Dicarboxylic acids, e.g., adipic acid, are prepared by reactively distilling and hydrolyzing admixture of a C.sub.1 -C.sub.4 alkyl aliphatic dicarboxylate and water, e.g., dimethyl adipate/water admixture, in liquid phase, in a distillation column, the lower end of which distillation column being charged with a gel of a crosslinked styrene/divinylbenzene resin bearing sulfonic acid substituents, the amount by weight of divinylbenzene comprising such resin ranging from 1% to 12% based on the total weight thereof and such resin having an exchange capacity of from 3 to 6.5 milliequivalents H.sup.+ /gram of dry resin, and including introducing the dicarboxylate/water admixture into the middle region of the column, withdrawing dicarboxylic acid from the base thereof and overhead distilling the alcohol of hydrolysis.

Abstract: Difunctional butenes are linearly dicarbonylated into 3-hexene-1,6-dioic acid or alkyl diesters thereof, well suited for the ultimate production of, e.g., adipic acid, by reacting such difunctional butene with carbon monoxide and, if appropriate, an alcohol, at an elevated temperature under superatmospheric pressure, in the presence of at least one source of hydrogen chloride and a catalytically effective amount of palladium, at least a portion of which palladium being in the zero oxidation state, as well as a quaternary onium chloride of nitrogen or phosphorus, the nitrogen or phosphorus atom being tetracoordinated to carbon atoms, with the proviso that the nitrogen atom may be coordinated to two pentavalent phosphorus atoms.