Organic Reactions Volume 4 - Sciencemadness Dot Org

PREPARATION OF AMINES BY REDUCTIVE ALKYLATION 191
simple alkylamines and activated carbonyl compounds, including
glyoxylic acid, pyruvic acid, and acetoacetic ester, have given lower
yields of the amines. 62
From Schiff*s Bases Derived from Aromatic Amines. Only isoamylaniline
and isoamyl-o-toluidine have been prepared by the reduction
of a SchifPs base derived from an aromatic amine and a simple aliphatic
aldehyde. 63 In these preparations a nickel catalyst was used; the
yields of the secondary amines obtained were not reported. A number
of Schiff's bases prepared from the hydroxyanilines and branched-chain
aldehydes have been reduced over platinum or nickel in good yields.
For example, the base from o-aminophenol and 2-ethylbutyraldehyde
was converted to the amine in 91% yield. 64
Pt
0~HOC6H4N=CHCH(C2H5)2 + H2 —> 0-HOC6H4NHCH2CH(C2Hs)2
Cinnamalaniline 65 and p-crotonalaminophenol M appear to be the
only unsaturated anils that have been reduced. The reduction was
effected with magnesium and methanol in the first instance, but the
yield of phenylpropylaniline was not reported. The reduction in the
second preparation was carried out with hydrogen and nickel catalyst,
and the yield of p~butylaminophenol was 33%. The SchifPs bases
derived from aniline (and several substituted anilines) and glucose or
sorbose have been converted to the amines by hydrogenation over nickel
catalyst, but the yields of the products are not available. 66
The condensation product of aniline and acetoacetic ester has been
reduced to the amine in 30% yield. 62 No other anil derived from a
ketone appears to have been reduced.
C6HBN=CCH2CO2C2H6 + H2 —> C6HBNHCHCH2CO2C2H5
CH8
CH3
The Schiff 7 S bases from aromatic aldehydes and aromatic amines are
readily available, and many of them have been reduced to secondary
amines. Catalytic reduction has been carried out most often over nickel
catalyst at moderate temperatures in either high-pressure or low-pressure
equipment. The reduction of benzalaniline over copper chromite at 175°
is quantitative, 23,67 but other anils apparently have not been reduced over
this catalyst,
62 Skita and WuIfF, Ann., 453, 190 (1927).
63 Mailhe, Bull. soc. chim. France, [4] 25, 324 (1919).
64 Fitch, U. S. pat. 2,270,215 [C. A., 36, 3189 (1942)].
65 Zechmeister and Truka, Ber., 63, 2883 (1930).
68 Salzberg, U, S. pat. 2,193,433 [C. A., 34, 4742 (1940)].
67 Adkins and Connor, J. Am. Chem. Soc, 53, 1091 (1931).