Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Subject of the present invention is a process for the
preparation of aromatic amine by reaction of cyclohexanone
azines or cyclohexenone azines in the gaseous phase in
the presence of catalysts containing noble metals of the
Thea subgroups of the Periodic Table.
Aromatic amine are intermediates for various apply-
cations, for example for distaffs, medicaments or plant
protecting agents.
Hitherto, aromatic amine have been prepared mainly
by reduction of the corresponding aromatic vitro compounds,
ox by reaction of the corresponding phenols with ammonia
at elevated temperature and pressure.
Thus, these processes depend on the availability of
the corresponding vitro compounds and phenols, respectively.
Since in the nitration of aromatic compounds different
isomers are formed in any case, the problem of separation
arises often, which has to be solved either before the
reduction, that is, in the stage of the vitro compounds,
or after the reduction, that is, in the amine stage. React
lion of phenols with ammonia requires much technological and apparatus expenditure. Moreover, these phenols are
often obtained from bituminous coal tar, so for example
sum. m-xylenol.
It was therefore the object of the present invention
to provide a method for preparing aromatic amine which
is independent of aromatic preliminary stages and starts
from simple aliphatic basis substances such as cycloali-
phatic kittens.
Cyclic kittens, for example cyclohexanone, are pro-
pared on a large scale by oxidation of cycloaliphatic
compounds. Unsaturated cyclic kittens, for example 3,5-
dialkylcyclohexenones, are easily obtainable from aide-
hypes and kowtow esters (see German Offenlegungsschrift
No. 2,654,850).
According to I Horning (~T.Am.Chem.Soc. 69, 1907
(19~7)), cyclohexenone is converted to aniline by reacting
the cyclohexenone with hydrazine and catalytically de-
hydrogel~atincr the cyclohexenone amine so formed in the
liquid phase at temperatures of from 136 to Sweeney tile
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presence of Pd/C catalysts:
R1 / R1 R1
ON _ N _ Pd/C
.
However, an economic manufacture of aromatic amine
according to this process is impossible because of the
yields attaining merely about 50 I.
There has now been found a process for the pro-
parathion of aromatic amine of the formulae It or It
` NH2
It
in which R1 through R5 each are hydrogen or C1-C6-alkyl,
or one of these radicals is phenol, which comprises
passing a cyclohexenone amine or cyclohexanone amine
of the formulae Ida or Jib
ON 1 ON I--
Ida : Irk
in which R1 through R5 are as defined above, in the
gaseous phase, at a temperature of from 200 to 500~C,
over a catalyst containing at least one noble metal of
the Thea subgroup of the Periodic Table.
The compounds of the formula Ida can be prepared
according to the following scheme (German Offenlegungs-
shrift No. 2,654,850; Ann. 281 104 (1894~):
us
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O ' O
I 2 + CRY ODOR -~2 COO
2 I
ODOR ~,~H21 ~12 COOP
. COREY
0
COY
Clue ~;~ R1~
2 ..
The cyclohexanone azines of the formula Jib are pro-
pared from cycloaliphatic kittens such as-cyclohexanoner
methylcyclohexanone, cyclohexenyl-cyclohexanone, and
hydrazine.
Generally the radicals R1 through R5 together have
no more than 12 carbon atoms. The C1-C6-alkyl radicals
for which R1 through R5 may stand can be linear, branched
or cyclic. One of the radicals R1 through R5 may alter-
natively be a phenol radical, optionally substituted for example by halogen, C1-C6-alkyl.or C1-C6-alkoxy. Prefer-
ably, however, it is unsubstituted or monosubstituted.
For the conversion of the azines to amine according
to the invention, Thor are generally used catalysts con-
twining ruthenium, rhodium, palladium, iridium or plating
us or mixtures thereof; palladium, platinum or palladium/
platinum being preferred.
Normally, carrier catalysts, for example on carton,
Sue, Allah, alumosilicates, spineless, chromium oxide/
Sue
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aluminum oxide, or zealots as carriers, are employed.
The concentration of the noble metal on the carrier is
generally from 0.05 to 10, preferably 0.2 to 5, and
especially 0.3 to 2.5, weight %, each relative to the
weight of the carrier. The noble metals are applied to
the carrier as compounds, and preferably reduced before
starting the reaction, for example by passing hydrogen
over them.
The catalyst may be arranged in the form of a solid
bed, moving bed or fluidized bed.
The reaction temperature is generally from 200 to
500C, preferably 250 to 400C, and especially 270 to
380C.
The reaction is usually carried out under reduced
pressure of down to about 10 mar, or under normal
pressure; elevated pressure of up to about 20 bars, how-
ever, being possible, Preferably, a carrier gas is used
for the transport of the amine over the catalyst. Suitable
carrier gases are particularly hydrogen, nitrogen, NH3,
argon, COY, methane, steam, ethylene or propylene.
Before the reaction, the amine may be diluted with
readily volatile solvents such as hydrocarbons, ethers,
especially glycol and polyglycol dialkyl ethers, or water.
The following Examples illustrate the invention.
The liter amounts of No and Ho are relative to the
standard (0C, 1.013 bar).
E X A M P L E 1:
In a glass reactor having a diameter of 18 mm and
a length of I cm, there were arranged from top to
bottom first a glass ball layer having a thickness of
5cm, immediately thereafter a catalyst layer having a
thickness of 16 cm and consisting of 1 weight of Pod
on Sue balls. In a No current, the reactor was heated
to 300C, subsequently activated for 2 hours at 280C
with I l/h of nitrogen and 6 lull of hydrogen. There
after, 100 g of a mixture of 80 g of dimethyl-diglycol
and 20 g of 3,5-dimethyl-cyclohexell-2-one~azine-1
boo 105C) and simultaneously I l of nitrogen and
Lowe ~5Z
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28 l of hydrogen were passed from above over the catalyst
heated at 260C by means of an electric heater.
During the second hour, 48 g of product were ox-
twined at the reactor outlet. The result of a gas chrome
autograph analysis (GO) was 7.7 g of 3,5-dimethylaniline,
that is, 78 % of theory, and 1.2 g of dixylylamine - 13
of theory.
H3C / 3
Jo OH
>=/
H3C' SHEA
dixylylamine
E X A M P L E 2
Using the reactor and catalyst as described in En-
ample 1, a mixture of 20 g of 3-methyl-5-propyl-cyclo-
hexen-2-one-azine-1 boo 5 198 - 200C) and 80 g of
Tulane was reacted for 3 hours at 300C. Simultaneously,
60 l or No and 30 l of Ho were passed over the catalyst
within this period of time. The product condensed at
the reactor outlet contained according to GO annuluses
14 g of 3-methyl-5-propylaniline - 70 % of theory
(b.p.1 106C).
E X A M P L E 3
Using the reactor and catalyst as described in En-
ample 1, a mixture of 20 g of cyclohexanone amine and
of di-n-butyl ether was reacted for 2 hours at
270 - 280C. Simultaneously, 40 1 of No and 28 l of Ho
were passed within this time over the catalyst The pro
duct collected at the reactor outlet contained according
to GO analysis 15.1 g of aniline, 2.7 g of diphènylamine
and 1.0 g of unrequited cyclohexanone amine.
