Well look at the patent I posted.
Temperatures at which the reaction can be run vary from -20.degree. C. to 65.degree. C. Preferred temperatures for the practice of the present invention are from 0.degree. C. to 55.degree. C., with the most preferred temperature being at or about room (ambient) temperature. The reaction is run at ambient (atmospheric) pressure, and so, in any case, the reaction temperature cannot be above the boiling point of the reaction solution chosen.
Another advantage is obviation of the need to wait for liquid ammonia or methylamine to evaporate from the reaction mixture after the reduction is completed, as is the case with other reduction conditions. The use of higher boiling amines allows for their recovery and recycling from the reaction mixture.
A still further advantage is that using an aliphatic amine permits solubilization of the organic substrate without ether or tetrahydrofuran which avoids the use of highly flammable ether co-solvents, and also the possibility of two phase reaction mixtures.
Another further advantage is that the reaction may be run at or around room temperature, instead of having the necessity for low temperature apparatus, such as Dewar condensers, and fume hoods to remove ammonia or methylamine as it evaporates. Ammonia boils at -33.degree. C. and methylamine at -6.3.degree. C. while ethylamine, the lowest boiling of the amines useful in the present invention boils at 16.6.degree. and the highest boiling, n-butylamine, at 78.degree.. Room temperature (68.degree. F.) converts to 20.degree. C. n-Propylamine has a bp of 48.degree.-49.degree. C. and isopropylamine has a bp of 33.degree.-44.degree. C.
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