Dsm IP Assets B.v.

Roche Vitamins Inc.

Felix Roessler

Werner Bonrath

Reinhard Karge

Oliver Gerald Degischer

The present invention relates to a process for the manufacture of cyclic thio esters (thiolactones) and related compounds by hydrogenation of cyclic thioanhydrides in the presence of metal catalysts.

Manufacture of thiolactones

The present invention relates to a process for the manufacture of cyclic monocarboxylic esters (lactones) and related compounds by hydrogenation of cyclic dicarboxylic acid anhydrides in the presence of metal catalysts.

Manufacture of lactones

A process for the modification of a hydrogenation catalyst of the Raney nickel, Raney cobalt, nickel-on-carrier or cobalt-on-carrier type, which process includes treating the hydrogenation catalyst at temperatures of about 0&deg; C. to about 120&deg; C. with carbon monoxide, carbon dioxide, formaldehyde, a lower aliphatic aldehyde, an aromatic aldehyde, an aliphatic ketone, an aromatic ketone, a mixed aliphatic/aromatic ketone, glyoxal, pyruvaldehyde or glyoxylic acid as the modification agent in a liquid dispersion medium consisting of water or an organic solvent for a duration of about 15 minutes to about 24 hours. When the thus-modified catalyst is used in the hydrogenation of a nitrile to the corresponding amine, the selectivity is increased, and significantly favors the amount of the primary amine vis-&agrave;-vis the undesired secondary amine in the hydrogenation product as compared to when the corresponding unmodified catalyst is employed. The present invention concerns, in a second aspect, a process for the hydrogenation of a nitrile to the corresponding primary amine using a thus-modified catalyst.

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Kaiseraugst, Switzerland

Felix Roessler