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.

Abstract: Diesters of hexene-1,6-dioic acids are prepared by reacting at least one 1,2-dialkoxy-3-butene with carbon monoxide in the presence of a catalytically effective amount of a palladium-based catalyst and a halogen compound, in liquid phase, at elevated temperature and at superatmospheric pressure.

Abstract: The catalyst system is characterized in that it comprises:at least one platinum complex of formula LPtX.sub.2 in which L is an organic compound containing at least two phosphorus atoms capable of coordinating platinum and X is a halogen atom, andat least one combination formed between iron and an alkene carbonate, the alkene group preferably containing from 2 to 6 carbon atoms.The process for its preparation is characterized in that at least one combination formed between iron adn the alkene carbonate is reacted with at least one platinum complex of formula LPtX.sub.2 in at least one solvent for the said complex, at a temperature of between 10.degree. C. and the boiling point of the said solvent. The combination of iron and of an alkene carbonate may be formed by electrochemical reduction.

Abstract: Alkyl acrylates are catalytically dimerized, e.g., to produce alkyl diesters of dihydromuconic acid, in the presence of a catalytically effective amount of palladium, tetrafluoroboric acid and a hydrogenophosphonium tetrafluoroborate, and wherein the palladium concentration ranges from 0.1 to 3 mmol per mole of said at least one alkyl acrylate, the reaction temperature ranges from 70.degree. to 150.degree. C. and the hydrogenophosphonium tetrafluoroborate concentration is at least 6 mmol per mole of said at least one alkyl acrylate.

Abstract: The catalytic system comprises:at least one platinum complex of formula LPtX.sub.2 in which L is an organic compound containing at least two phosphorus atoms capable of coordinating platinum and X is a halogen atom, andat least organic tin compound comprising at least one Sn--O bond and at least one C--O bond.Application to the production of aldehydes by the hydroformlation of an ethylenically unsaturated organic compound, by reacting the said organic compound, at a temperature of between 10.degree. C. and 300.degree. C. and under a pressure of between 1 and 350 bars, with a mixture of carbon monoxide and hydrogen in the presence of an effective amount of the said catalytic system.