Organic Reactions Volume 4 - Sciencemadness Dot Org

188 ORGANIC REACTIONS
veratric aldehyde, and furfural, and only a few yields have been reported.
Most secondary amines which might be made from such combinations
are prepared by reduction of the SchifPs base (see p. 191) rather than
by the direct procedure. It is of interest that the yield of N-benzyl-/3naphthylamine
obtained by the reductive alkylation of 0-naphthylamine
with benzaldehyde, hydrogen, and nickel catalyst is much better (58%)
than that reported (24%) for the similar preparation of the a-amine. 36
,NH2 Ni r^^^^SNHCHsCeHs
+ C6H5CHO + H2 —> f J J +H2O
Apparently no advantage is to be gained by the reductive alkylation
of a nitro, nitroso, or azo compound with an aromatic aldehyde; the
yields of benzylaniline so obtained from nitrobenzene, 43 nitrosobenzene, 47
and azobenzene 48 are only 33%, 47%, and 49%, respectively.
Aromatic Amines, Aromatic Nitro, Nitroso, or Azo Compounds and
Ketones. N-Isopropylaniline is obtained in 31% yield from aniline,
acetone, zinc, and hydrochloric acid; 42 under the same conditions, Nisopropylmesidine
is obtained in only 18% yield. p-Aminophenol is
CH3
CH3
H3C^ANH2 -f- CH3COCH3 -f 2(H) ^±52-> H3c/^NHCH(CH3)2 + H2O
"CH3
(^H3
converted to the N-isopropyl derivative when an acetone solution of the
base is heated to the boiling point and then reduced over platinum
catalyst; 49 none of the secondary amine is obtained when hydrogenation
at room temperature is attempted. 50
The highest reported yield in a preparation of this type is that (91%)
of the secondary amine from a-naphthylamine and N,N-diethylacetopropylamine.
51 This is also the only reported use of palladium catalyst
NH2
+ CH3COCH2CH2CH2N(C2HS)2 + H2 -^>
NHCH(CH3)CH2CH2CH2N(C2HS)2 + H2O
in the preparation of a secondary amine by a reductive alkylation involving
a primary aromatic amine and a monoketone. It is possible that
49 Major, J. Am. Chem. Soc, 53, 2803 (1931).
50 Major, J. Am. Chem. SoC1 53, 1901 (1931).
51 Bergman, Brit. pat. 547,301 [C. A., 37, 5985 (1943)].