Reactions of mixed dialkyl- and trialkylamines over Pd/γ-Al2O3

The reactions of the dialkylamines dipentylamine and N  -methylhexylamine and the trialkylamines trihexylamine and N,NN,N-dihexylmethylamine were studied over Pd/γ-Al2O3 at 300 °C and 3 MPa. Dipentylamine reacted by disproportionation to tripentylamine and pentylamine and by hydrogenolysis to pentylamine and pentane and pentene. Tripentylamine and N,NN,N-dihexylmethylamine reacted by hydrogenolysis to dialkylamines and alkanes and alkenes. N  -methylhexylamine reacted by disproportionation to the mixed trialkylamines N,NN,N-dihexylmethylamine and N,NN,N-dimethylhexylamine, as well as by hydrogenolysis to the alkylamines hexylamine and methylamine and the alkanes hexane and methane. The initial rates of formation of the mixed trialkylamines were almost equal. This indicates that not only the hexyl group, but also the methyl group can be transferred between two N  -methylhexylamine molecules. In the reaction between dipentylamine and N,NN,N-dihexylmethylamine, more N,NN,N-dipentylmethylamine than N,NN,N-dipentylhexylamine was formed. The comparable rates of transfer of methyl and other alkyl groups prove that enamines are not the only intermediates in the reactions of dialkyl- and trialkylamines.