HAROLD SHECHTER A N D SURJAN SINGHRAWALAY
1706 [CONTRIBUTIOS FROM
THE
DEPARTMEXT O F CHEMISTRY, THEOHIO
STATE
Vol. 86
UNIVERSITY, COLUMBUS 10, O H I O ]
Oxidation of Primary, Secondary, and Tertiary Amines with Neutral Potassium Permanganate. I1 B Y HAROLD SHECHTERIa
A N D SURJAN S I N G H
R A W A L Ac Y .d ~ ~
RECEIVED ~ U C C S T21, 1963 Oxidation of benzhydrylamine (111)with buffered permanganate a t 25' gave S-diphenylmethylenebenzhydrylamine and ammonia; in hot excess permanganate, benzophenone azine ( V I I ) is formed. Reaction of benzophenoneimine ( I V ) with neutral permanganate in aqueous t-butyl alcohol yielded 1-11 and benzophenone. Dibenzylaxnines are oxidized t o their corresponding N- [ol-(dibenzy1amino)-benzyl]-benzamides ( X I - X I I I ) ; alternate structures have been proposed for t h e products previously reported from such oxidations. N-Phenylbenzhydrylamine ( X X I I ) is converted by permanganate t o S-diphenylmethyleneaniline ( X X I I I ) and S-(diphenylmethyl)-S,S',1,1-tetraphenylmethanediamine(XXIV), Tributylamine (XXI.) reacts with neutral permanganate t o give K,N-dibutylformamide ( X X X I ) , K,S-dibutylbutyramide ( X X X ) ,dibutylamine ( X X V I I I ) , butyraldehyde ( X S I S ) ,and butyric acid. Benzaldehyde and benzoic acid are t h e products of oxidation of tribenzylarnine ( X X S I I ) . Possible mechanisms of these various oxidations are discussed.
Primary carbinamines are oxidized by unbuffered potassium permanganate to aldehydeszaand carboxylic acids.?b Certain control of reaction of specific seconda r y carbinamines with unbuffered permanganate to give nitroso compounds2c * oximes,2c and iminesZe results from effecting oxidation in the presence of simple aldehydes or ketones. Tertiary carbinamines are converted slowly to nitro compounds by aqueous permanganate. 2f Secondary dialkylamines have been oxidized to their corresponding carboxylic acidszb; secondary and tertiary amines containing suhstituted benzyl groups are converted to their corresponding benzaldehydes or benzoic acids by acidic potassium permanganate. * g I t has been recently reported? t h a t neutral permanganate as derived from potassium permanganate and excess calcium sulfate in aqueous t-butyl alcohol is an excellent oxidant for conversion of substituted benzylamines to substituted N- [a-(benzylidene)-benzyl]benzamides (I) and N,N-(iminodibenzy1idene)-bis-
[benzamides] (11). I t was suggested that in these complex transformations important reactions involve oxidation of the benzylamines to benzalimines, condensation of the benzalimines and benzylamines, and subsequent oxidation to products. As an extension of a study of the utility of neutral permanganate as an oxidant of amines and to obtain additional inforniation of the courses and mechanisms of such reactions, an investigation has been made of oxidation of benzhydrylamine, various dibenzylamines, N-phenylbenzhydrylamine, tributylamine, and tribenzylamine, respectively. Results and Discussion Oxidation of Benzhydry1amine.-Reaction of benzhydrylamine (111) with potassium permanganate and calcium sulfate in water-acetone ( I : 10) a t 23" yields an instable adduct (presumably V) which decomposes into N-diphenylmethylenebenzhydrylamine (VI, 74%) and ammonia. On the basis of the products of the present study and the previous report2e that benzhydrylamine (111) is oxidized by potassium permanganate in acetone to benzophenoneimine ( I V ) , it is apparent that a process of the type indicated in eq. 1 occurs in conversion of I11 to VI. The present system is thus of interest in t h a t in the oxidation medium, condensation to give V takes place rather than hydrolysis or oxidation of the reaction intermediates to benzophenone. C6H5
CeHs
\
\
hlnOc
CHNHz
-+
/
- Hz0
/
CeHs
CsH5 KH2
v
--------+
Iv
CaH6
I11
--+
r5)XHCH
