Amines, tertiary, hydrogenation promoters

For more selective hydrogenations, supported 5—10 wt % palladium on activated carbon is preferred for reductions in which ring hydrogenation is not wanted. Mild conditions, a neutral solvent, and a stoichiometric amount of hydrogen are used to avoid ring hydrogenation. There are also appHcations for 35—40 wt % cobalt on kieselguhr, copper chromite (nonpromoted or promoted with barium), 5—10 wt % platinum on activated carbon, platinum (IV) oxide (Adams catalyst), and rhenium heptasulfide. Alcohol yields can sometimes be increased by the use of nonpolar (nonacidic) solvents and small amounts of bases, such as tertiary amines, which act as catalyst inhibitors. 

In summary, the preparation of polyimidazolinones from polyamides containing a-aminoacid units (3, X = NH) can now be considered to be a general reaction provided that Rz and/or R3 are not hydrogen. When the polyamide has additional secondary or tertiary amine functionality in the backbone, cyclodehydration appears to be exceptionally facile. In the absence of amine functionality however, a catalyst is necessary to promote cyclization. Further studies of this new heterocyclic polymer system are ongoing in our laboratories. 

The ease of hydrogenolysis of benzyl amines depends on the nature of the substituents on the nitrogen atom. The debenzylation of tertiary benzyl amines takes place over palladium on charcoal at 25°-50°C and 2-4 atmospheres of hydrogen (Eqn. 20.43). 2 Platinum and rhodium catalysts generally promote... 

Copper-chromite type catalysts supported by alumina or graphite and promoted with barium were used for the one step synthesis of tertiary fatty amines (R2NCH3 or RN(CH3)2) from nitrile, methanol and hydrogen. The surface composition of the catalysts was studied by XPS and by adsorption experiments. A correlation was found between the selectivity and the presence of a well-dispersed CUC1O2 phase, stabilized with barium. Moreover the elements influencing the stability of the copper catalysts were also studied and we remarked the effect of the promoter or/and of the support on the variation of the copper surface area in the presence of water or ammonia. These modifications were examined in relation with the change of the catalytic properties with time-on-stream. 

For example, a secondary alcohol of an average molecular weight of 202, containing 12—14 carbon atoms, is introduced into a reaction tube packed with a cobalt promoted zirconium catalyst on alumina at a rate of 60 mL/h along with liquid ammonia (90 mL/h) and hydrogen (5 L/h) to produce an amine mixture composed of 92.2% primary amine, 2.15% secondary and tertiary amines, and 5.7% unreacted alcohol (52). The reaction, at 180-190 0 and 24 MPa ( 5 3500 psig), is run by withdrawing the liquid reaction product from the bottom of the reactor. 

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