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AssigneeRhodia Polyamide Intermediates
InventorsVincent Boschat, Philippe Leconte
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The present invention relates to a process for the hydrogenation of nitrile functional groups to amine functional groups. It relates more particularly to a process for the complete or partial hydrogenation of dinitrile compounds to diamine or aminonitrile compounds. The invention relates to a process for the hydrogenation of nitrile functional groups to amine functional groups using hydrogen in the presence of a hydrogenation catalyst and of a strong inorganic base preferably deriving from an alkali metal or alkaline earth metal. According to the invention, the process comprises a stage of conditioning the catalyst which consists in mixing the hydrogenation catalyst, a predetermined amount of strong inorganic base and a solvent in which the strong inorganic base is not very soluble. This solvent is an amine compound, such as hexamethylenediamine in the case of the hydrogenation of adiponitrile to HMD and/or aminocapronitrile.
Process for the hydrogenation of nitrile functional groups to amine functional groups using hydrogen in the presence of a hydrogenation catalyst and of a strong inorganic base deriving from an alkali metal or alkaline earth metal, characterized in that it comprises a stage of conditioning the catalyst which consists in mixing the catalyst, a predetermined amount of strong inorganic base to be associated with the catalyst and a solvent in which the strong inorganic base is not very soluble, the said mixture comprising the conditioned catalyst being fed into the hydrogenation reaction medium comprising the compound to be hydrogenated and optionally a solvent.
Process according to one of the preceding claims, characterized in that, when a liquid known as a storage liquid is associated with the use of the catalyst, in particular a catalyst based on Raney metal, the abovementioned solvent and the said storage liquid are soluble in one another, the strong inorganic base not being very soluble in the solution of the solvent and of the storage liquid.
Process according to one of the preceding claims, characterized in that the mixture for conditioning the catalyst comprises water.
Process according to one of the preceding claims, characterized in that the solvent is a compound comprising one or more amine functional groups or liquid ammonia.
Process according to one of the preceding claims, characterized in that the strong inorganic base is added to the liquid medium for storage of the Raney metal before the addition of the solvent.
Process according to one of the preceding claims, characterized in that the stage of conditioning the catalyst is carried out under an inert atmosphere.
Process according to one of the preceding claims, characterized in that it consists in hydrogenating a dinitrile to an aminonitrile and/or to a diamine.
Process according to one of the preceding claims, characterized in that the ratio by mass of the solvent to the liquid medium for storage of the catalyst or the water in the mixture for conditioning the catalyst is at least equal to 1.
Process according to one of the preceding claims, characterized in that the concentration of catalyst in the conditioning mixture is less than or equal to 30% by weight, expressed as weight of metal.
Process according to one of the preceding claims, characterized in that the catalyst comprises doping elements.
Dependencies are inferred from the claim text.