Abstract: A method for preparing carboxylic acids by carbonylating a reagent, particularly an alcohol, in the presence of a rhodium catalyst. According to the method, the liquid phase reaction is carried out in a first zone in the presence of a rhodium catalyst, and the resulting reaction mixture is partially vaporised in a second zone. The vaporised fraction containing the carboxylic acid is later purified and the unvaporised liquid fraction containing the catalyst is recirculated to the first zone. The method is charactracterised in that said unvaporised fraction is contacted with carbon monoxide in such a way that this compound is not returned to the second zone.

Abstract: A fluid-circulation heat exchanger including a porous body, made of thermally conductive material, in contact with at least one portion of a part to be cooled. The fluid flows through this porous body. The porous body has pores which generate directional changes of the fluid. These pores are large enough for the head loss of the fluid to be as small as possible on passage through the porous body. Application, in particular, to electron tubes.

Abstract: The present invention relates to a stack device comprising a stack of gate turnoff thyristors GTO, of freewheel diodes DRL, and of diodes D, for a semiconductor circuit, said stack device including power supply electrical connection terminals +HT and -HT, and an output terminal PM, together with electrical connection terminals Cs and Cc between said diodes Ds and Dc and a protection circuit P, wherein the geometrical organization of the wiring of said electrical connection terminals +HT, PM, and -HT is predetermined so as to enable the disposition of said thyristors GTO and of said freewheel diodes in said stack to be modified in order to obtain different electrical functions for the semiconductor circuit.

Abstract: A method for preparing carboxylic acids including (n+1) carbon atoms, or the related esters, by liquid phase carbonylation of an alcohol including (n) carbon atoms, in the presence of a uniform catalytic system based on at least one iridium compound and at least one halogenated promoter. In particular, the method is characterised in that the content of ester related to said carboxylic acid and alcohol is kept between 15 and 35% in the medium during the reaction, while the halogenated promoter content is kept between 10 and 20%, and the partial carbon monoxide pressure is 40-200 bar. Said method enables both the rate of carbonylation and the acetic acid selectivity to be increased.

Abstract: Preparation of carboxylic acids or corresponding esters by reacting an alcohol with carbon monoxide in the presence of an iridium catalyst and a halogen promoter. The reaction involves a reaction mixture composed of more than 0% to 10% water, more than 0% to 10% halogen promoter, 2% to 40% of an ester corresponding to the reaction of alcohol with the acid, soluble iodides in an amount such that the atomic ratio of iodides to iridium varies between more than 0 and 10, the carboxylic acid being used as the reaction solvent.

Abstract: A method for preparing carboxylic acids by carbonylating a reagent, particularly an alcohol, in the presence of an iridium catalyst. According to the method, the liquid phase reaction is carried out in a first zone in the presence of an iridium catalyst, and the resulting reaction mixture is partially vaporised in a second zone. The vaporised fraction containing the carboxylic acid is later purified and the unvaporised liquid fraction containing the catalyst is recirculated to the first zone. The method is characterised in that said unvaporised fraction is contacted with carbon monoxide in such a way that this compound is not returned to the second zone.

Abstract: The alkyl adipates are prepared by reacting admixture consisting essentially of alkyl 3-pentenoate and alkyl 2-pentenoate with carbon monoxide and an alcohol, at elevated temperature, under superatmospheric pressure and in the presence of a catalytically effective amount of cobalt or a cobalt compound and a nitrogenous heterocyclic base.

Abstract: Process for the preparation of a carboxylic acid or ester thereof. The process includes reacting at least one alcohol, alkyl or aryl halide, ether or ester, with carbon monoxide, in the presence of a catalytically effective amount of at least one rhodium compound or rhodium metal, at least one iridium compound or iridium metal, or at least one mixed rhodium/iridium compound, and at least one halogen-containing promoter therefor.

Abstract: At least a fraction of at least one branched, saturated aliphatic diacid having 6 carbon atoms, for example 2-methylglutaric acid and/or 2-ethylsuccinic acid and/or dimethylsuccinic acid, is separated from admixtures thereof with adipic acid, by at least partially converting such at least one aliphatic diacid into the corresponding anhydride thereof, and removing the corresponding anhydride or the adipic acid from the medium of conversion/anhydridization, for example by contemporaneous or subsequent distillation, or by crystallization.

Abstract: Adipic acid is selectivity prepared by reacting water and carbon monoxide with at least one pentenic acid, in the presence of a catalytically effective amount of an iridium-based catalyst and at least one iodinated promoter therefor at an elevated temperature, at a pressure greater than atmospheric and in at least one solvent medium which comprises a saturated aliphatic or cycloaliphatic hydrocarbon or halogenated derivative thereof, an aromatic hydrocarbon or halogenated derivative thereof, or an aliphatic, aromatic or mixed ether, and wherein the I/Ir atomic ratio is less than 20.

Abstract: Unsaturated carboxylic acids, e.g., pentenoic acids, are prepared by carbonylating an allylic butenol and/or carboxylate ester thereof with carbon monoxide, in the presence of a catalytically effective amount of an iridium catalyst and an iodinated or brominated promoter therefor, and optionally, a copromoter, notably wherein the promoter/Ir molar ratio ranges from 0.1:1 to 20:1. The final product acids, e.g., 3-pentenoic acid, are themselves readily hydroxycarbonylated, for example, into adipic acid, via reaction with carbon monoxide and water.

Abstract: Hexene-1,6-dioic acids, e.g., hex-3-ene-l,6-dioic acid, are prepared by reacting carbon monoxide and water with at least one diacyloxylated butene in a polar, aprotic and basic solvent, in the presence of a catalytically effective amount of palladium values, optionally a halide, and at least one inorganic halide, the cation of which being an alkali or alkaline earth metal and the anion of which being a chloride or bromide.

Abstract: The secondary water supply for a steam generator is provided by a toroidal or semitoroidal collector (38) placed in the bottom of the annular recirculation space (32) of the generator, in a larger diameter part (36) of the outer envelope. The collector (38) has holes (40) ensuring a vertical mean flow of the secondary water into the annular space (32). The cross-section of the holes is chosen in such a way as to trap in the collector the migrating bodies or members from the secondary water circuit and which could damage the steam generator tubes. At least one access orifice makes it possible to extract these migrating bodies from the collector during maintenance operations.

Abstract: Adipic acid is selectively prepared via hydrocarboxylation of pentenoic acids, by reacting water and carbon monoxide with at least one pentenoic acid, in the presence of a catalytically effective amount of a rhodium-based catalyst and at least one iodinated promoter therefor, at a temperature ranging from 100.degree. to 240.degree. C. and a pressure greater than atmospheric, and wherein (a) such reaction is carried out in the absence of a third reaction solvent and (b) the carbon monoxide partial pressure, measured at 25.degree. C., is less than or equal to 20 bar.

Abstract: Adipic acid is prepared by hydrocarboxylating at least one pentenic acid in the presence of a catalytically effective amount of rhodium values, whether metallic rhodium or a compound thereof, and an iodine-containing promoter therefor, as well as in the presence of a cocatalytically effective amount of at least one of iridium, ruthenium, osmium or compound thereof.

Abstract: Adipic acid is selectively prepared by reacting water and carbon monoxide with at least one pentenic acid, in the presence of an iridium-based catalyst and at least one iodine-containing promoter therefor, at an elevated temperature, at a pressure greater than atmospheric pressure, in a reaction medium comprising at least one saturated aliphatic carboxylic acid, ethylenically unsaturated aliphatic carboxylic acid or aromatic carboxylic acid having not more than 20 carbon atoms, with the I/Ir atomic ratio being less than 10.

Abstract: Adipic acid is selectively prepared, in good yields, by reacting at least one pentenic acid with water and carbon monoxide, the partial pressure of which, measured at 25.degree. C., being less than or equal to 12 bar, in the presence of a catalytically effective amount of a rhodium-based catalyst and at least one iodine-containing promoter therefor, at a temperature ranging from 100.degree. to 240.degree. C. and at superatmospheric pressure, and in a liquid reaction medium which comprises at least one hydrocarbon or chlorocarbon solvent, whether a saturated aliphatic or cycloaliphatic hydrocarbon, aromatic hydrocarbon or chlorinated derivative thereof.

Abstract: Adipic acid is selectively prepared, in good yields, by reacting at least one pentenic acid with water and carbon monoxide, the partial pressure of which, measured at 25.degree. C., being less than or equal to 20 bar, in the presence of a catalytically effective amount of a rhodium-based catalyst and at least one iodine-containing promoter therefor, at a temperature ranging from 100.degree. to 240.degree. C. and at superatmospheric pressure, and in a liquid reaction medium which comprises a saturated aliphatic or aromatic carboxylic acid having up to 20 carbon atoms.

Abstract: Hexene-1,6-dioic acids, e.g., hex-3-ene-1,6-dioic acid, are prepared by reacting carbon monoxide with at least one butenediol, in a polar, aprotic, basic solvent, in the presence of a catalytically effective amount of palladium values and at least one inorganic halide, the cation of which halide being an alkali or alkaline earth metal and the anion thereof being a chloride or bromide.

Abstract: Hexenedioic acid diesters, e.g., a hex-3-ene-1,6-dioic acid diester, are prepared by reacting carbon monoxide and an alcohol with at least one diacyloxylated butene in a polar, aprotic, basic solvent, in the presence of a catalytically effective amount of palladium values and at least one inorganic halide, the cation of which halide being an alkali or alkaline earth metal and the anion thereof being a chloride or bromide.