Organic Reactions Volume 4 - Sciencemadness Dot Org

PREPARATION OF AMINES BY REDUCTIVE ALKYLATION 193
4-amino-l-phenyl-2,3-dimethyl-5-pyrazolone to the tertiary amine in
unspecified yield. 18 ' 72
In an experiment in which ethylamine was treated with a mixture of
acetaldehyde and benzaldehyde, hydrogen, and platinum catalyst,
diethylbenzylamine (28% yield) was obtained. 11 This appears to be
the only attempt at the simultaneous introduction of two different alkyl
groups by the use of two aldehydes.
Only one instance has been recorded of the conversion of a primary
aliphatic amine to a tertiary amine by reductive alkylation with a simple
ketone: 4-amino-l-phenyl-2,3-dimethyl-5-pyrazolone gave the diisopropylamino
compound in unspecified yield on treatment with acetone,
hydrogen, and platinum catalyst. 18 Methylamine and ethylamine have
been reductively alkylated by treatment with a mixture of formaldehyde
or acetaldehyde and a 1,2- or 1,3-diketone, hydrogen, and platinum
catalyst. 73 ' 74 The products were dialkylaminoalcohols, generally obtained
in unreported yields. The cyclic tertiary amine was the major
Pt
CH3NH2 + C6H6COCOCH3 + CH2O + 3H2 —>
C6H5CHOHCH(CH3)N(CHS)2 + 2H2O
product from cyclohexylamine, acetonylacetone, hydrogen, and platinum
catalyst. 29 ' 30
Pt CH2 CH2
C6HuNH2 + CH3COCH2CH2COCH3 + 2H2 _> \ I + 2H2O
H3CCH CHCH3
v
C6Hu
From Primary Aromatic Amines, Nitro Compounds, or Azo Compounds
and Aldehydes and Ketones. Primary aromatic amines with substituents
in the 2,4 or 2,4,6 positions have been converted to the dimethyl
derivatives by reductive alkylation with formaldehyde, zinc, and hydrochloric
acid; 42 > 75 > 76 other aldehydes have not been tested. The yields in
these methylations ranged from 50% to 90%. The primary amines
employed carried alkyl groups and halogen atoms as substituents in the
ring. No variations in yield ascribable to steric hindrance were noted,
but the removal of iodine atoms from the ortho and para positions 76
and of bromine atoms from ortho positions was noted. 76 Tribromoaniline,
72 1.G. Farbenind. A.-G., Ger. pat. 479,348 (Chem. Zentr., 1929, II, 1692).
73 Skita and KeU, Ber., 63, 34 (1930).
74 Skita and Keil, Monabsh., 5S-54, 753 (1929).
75 Emerson and Ringwald, J". Am. Chem. Soc, 63, 2843 (1941).
76 Emerson, Dorf, and Deutschman, J, Am. Chem. Soc., 62, 2159 (1940).