Organic Reactions Volume 4 - Sciencemadness Dot Org

PREPARATION OF AMINES BY REDUCTIVE ALKYLATION 185
An example of the relatively few recorded reductive alkylations of
primary aliphatic amines by simple aromatic ketones is that of ethanolamine
by acetophenone. 26 The yield is 95%. No simple diaryl ketone
Pt
C6H5COCH3 + H2NCH2CH2OH + H2—^C6H5CHNHCH2CH2OH + H2O
CH3
has been used in a reductive alkylation with a primary aliphatic amine.
Diketones containing one or more aryl groups react in the same way
as the aliphatic diketones. Keto amines are obtained with palladium
catalyst, 28 and amino alcohols with platinum catalyst. 29
Pd
C6H5COCOCH3 + C6HnNH2 + H2-* C6H6COCHNHC6Hi1 (19%)
CH3
C6H5COCOC6H6 + C6H11NH2 + H2 —> C6H5COCHNHC6H11 (24%)
I
C6H5
O6H6COCOC6H6 + C6HnNH2 + 2H2 A C6H6CHOHCHNHC6Hn
I
C6H5
Aromatic Amines and Aldehydes; Aromatic Nitro Compounds, Azo
Compounds, etc., and Aldehydes. Aniline is converted to ethylaniline
by treatment with acetaldehyde and hydrogen in the presence
of nickel or platinum, 32 ' 33 or by reduction with zinc and sulfuric 34 or
sulfurous acid. 35 Most of the higher n-alkylanilines have been prepared
by reduction with hydrogen and nickel catalyst (yields, 45-65%); 32
the presence of a small quantity of sodium acetate (1 g. for a 0.1 M run)
is desirable. In reductive alkylations with aldehydes, hydrogen, and
nickel catalyst, a-naphthylamine gives 88% of the N-ethyl derivative
and 80% of the N-n-butyl derivative, 36 whereas from /3-naphthylamine
the yields of the corresponding secondary amines are 64% and 63%,
respectively. The number of substituted anilines which have been
alkylated by this method is relatively small. The yields from p-toluidine,
p-anisidine, and p-aminophenol are about the same as those from aniline.
Aluminum and aqueous sodium hydroxide have been used to effect the
reduction in some alkylations of p-aminophenol, but the yields of the
32 Emerson and Walters, ,/. Am. Chem. Soc, 60, 2023 (1938).
38 Emerson, U. S. pat. 2,298,284 [C, A., 37, 1450 (1943)].
34 Lockemaim, Ger. pat. 491,856 [Frdl., 16, 356 (1931)].
M Chemische Fabriken Vorm. Weiler-ter Meer, Ger. pat. 376,013 [Frdl, 14, 398 (1926].)
3(1 Emerson and Eobb, /. Am. Chem, Soc, 61, 3145 (1939).