PROCESS FOR THE PRODUCTION OF N-ALKYLARYLAMINES

PROCEDE D'OBTENTION DE N-ALKYLARYLAMINES

English Abstract

ABSTRACT OF THE DISCLOSURE
A process for the production of an N-alkylarylamine the
catalytic reaction of an arylamine with an alkanol in the
gaseous phase at a temperature of 180° to 400°C. The catalyst
is copper or copper oside on a silicate carrier, such as, a
kaoline-sodium silicate carrier.

Claims

What is claimed is:
1. Process for the production of an N-alkylarylamine by
reaction of an arylamine with an alkanol in the gaseous phase
at a temperature of 180° to 400°C. in the presence of a catalyst,
characterized in that the molar ratio of the arylamine to the
alkanol is from 0.5:1 to 0.5:20 and that the catalyst is copper
or copper oxide applied to a silicate-carrier.
2. Process as claimed in Claim 1 wherein the molar
ratio of arylamine to alkanol is 0.5 to 2.
3. Process as claimed in Claim 2 wherein the catalyst has
a specific surface of 10 to 100 m2/g.
4. Process as claimed in Claim 3 wherein the catalyst
consists of copper or copper oxide applied to a kaolin-sodium
silicate carrier.
5. Process as claimed in Claim 1 wherein the catalyst has
a specific surface of 12 to 25 m2/g.
6. Process as claimed in Claim 1 wherein the catalyst is
used in a solid bed reactor.
7. Process as claimed in Claim 6 wherein the reactants
have a tarry time of 4 to 100 seconds in the reactor.
8. Process as claimed in Claim 1 wherein the reaction is
conducted at a temperature of 220° to 350°C.
9. Process as claimed in Claim 1 wherein an inert carrier
gas is present during the reaction.
10. Process as claimed in Claim 9 wherein the inert
carrier gas is nitrogen.
11. Process as claimed in Claim 1 wherein the aryl amine
is an aromatic amine having the formula:
<IMG>
-9-

wherein R1 is a hydrogen atom or an alkyl moiety having 1 to
4 carbon atoms, R2 is a hydrogen atom, a cyano moiety, a nitro
moiety, an alkyl moiety having up to 4 carbon atoms or an
alkoxy moiety having up to 4 carbon atoms, and n is 1 or 2,
and wherein when n is 1, R2 can further be a phenyl moiety or
a moiety having the formula:
<IMG>
wherein R3 is an alkylene moiety having up to 3 carbon atoms or
an alkyl moiety having up to 3 carbon atoms and R9 is a hydro-
gen atom or an alkyl moiety having 1 to 4 carbon atoms.
12. Process as claimed in Claim 1 wherein the alkanol
has an alkyl moiety which has 1 to 4 carbon atoms.
13. Process as claimed in Claim 1 wherein the catalyst
has a specific surface of 12 to 25 m2/g, the catalyst is used
in a solid bed reactor, the reaction is conducted at a tempera-
ture of 220° to 350°C., an inert carrier gas is present during
the reaction, and 0.5 to 2 moles of alkanol per mole of aryl-
amine is used.
-10-

Description

~1~8447
BACKGROUND OF THIS INVENTION
1. Field of This Invention
This invention relates to the production of N-alkylaryl-
c~r)~/a~ n~s
amines by the catalytic reaction of aEy-lam~ and alkanols.
2. Prior Art
., ._, ~",
The production of N-alkylarylamines by reaction of
arylamines with alkanols is known. For example, aluminumoxide
or silicates have been used as catalyst in such reaction (see
German Patent No. 693,417 and German Patent No. 638,756). Such
catalysts have the disadvantage that their activity quickly f ~
decreases and thus their useful life is very limited. Carrier ~r
materials have also already been used as catalysts, which have
a content of oxyacids of phosphorus or their salts (see German
Patent No. 617,990). Such catalysts also have only a short use-
ful life. German A.S. 2,335,906 discloses catalysts consisting
of silicic acid, which have an inside surface of 50 to 500 m2/g i~
and which have a content of 0.1 to 20 percent of phosphoric acid.
At the same time, phosphoric acid or phosphoric acid alkylester ~,;
is continuously fed to the catalyst during the reaction. The
disadvantage of such process is the fact that large and serious
corrosion problems develop in the entire reactor system when- j
ever phosphoric acid is present, even if only in small i~.
quantities. Even further, the selectivity of the catalysts
leaves much to be desired with a view of the production of only
N-monoalkylarylamine.
i
..,~.
~ , .
~;. -
--2--

~84~7
BROAD DESCRIPTION OF THIS INVENTION
An object of this invention is to find a technicallysimple process for the production of an N-alkylarylamine,
especially a N-monoalkylarlyamine, from an arylamine and a
corresponding alkanol. Other objects and advantages are set
out herein or are obvious herefrom to one ordinarily skilled
in the art.
The objects and advantages of this invetion are
achieved by the process of this invention.
This invention involves the production of a N-alky-
larylamine by the catalytic reaction of an arylamine and an
alkanol in the gaseous state. The catalyst consists of copper
which has been applied to a silicate carrier. More specifically,
the catalysts consists of metallic copper or copper oxide
applied to a silicate carrier. Preferably the catalyst has
a specific surface of 10 to 100 m2/g~ most effectively 12 to
25 m2/g
Advantageously the catalyst is used in a solid bed
reactor. At the same time catalyst is used in a shaped form,
for example, in the form of cubes of pellets.
The conversion (reaction) of this invention is carried
out at a temperature of 180 to 450C. Particularly good results
are obtained at a temperature of 220 to 350C. The reaction
is generally carried at standard pressure. Sometimes a slightly
increased pressure, for example, up to 10 bar is used. Further-
more, the temperature and pressure conditions are selected such
that the reaction can be carried out in the gaseous phase.
Additionally it is advantageous also to use a carrier gas which
is inert under reaction conditions. Such a carrier gas is
nitroyen.

11~L84~7
The process of this invention is advantageously carried
out such that the catalyst is inserted into a solid bed reactor,
is heated to reaction temperature and then the mixture of
arylamine and alkanol is introduced and has a short tarry time,
for example, 4 to 100 seconds, in the reactor. The gaseous
reaction mixture is condensed; the organic layer is separated
A from the gaseous layer and the desired N-alkyarylamidc is iso-
lated from the organic layer.
Depending on whether in the main a N-monoalkylarylamine
/~ or a N-dialkylarylamine is to be obtained, .the molar ratio of
arylamine to alkanol can vary from 0.5:1 to 0.5:20. The pro-
cess of the invention is advantageously suited Lor the produc-
tion of N-monoarylamines; in this case, the molar ratio
of arylamine to alkanol is preferably 0.5 to 2.
Prefera~ly the aryl amine is an aromatic amine having the
formula:
~ )n
wherein Rl.is a hydrogen atom or an alkyl radical having 1 to
4 carbon atoms, R2 is a hydrogen atom, a cyano group, a nitro
group, an alkyl radical having up to 4 carbon atoms or an
alkoxy radical having up to 4 carbon atoms, and n is 1 or 2,
and wherein when n is 1, R2 can further be a phenyl radical
or a radical having the formula:
~ / 4
R3 ~ N~

~li84~7
wherein R3 is an alkylene radical having up to 3 carbon atoms
or an alkyl radical havinq uP to 3 carbon atoms and R4 is a
hydrogen atom or an alkyl radical having 1 to 4 carbon atoms.
Preferably the aromatic amines are those which are derived
from benzene and which have an amino group. Beside the amino
group, the preferred aromatic amines can have 1 or 2 substi~
tuents which are iner-t under the reaction conditions. Examples
0~ such substituents are alkyl radicals having 1 to 4 carbon
atoms, alkoxy radicals having 1 to 4 carbon atoms, cyano groups
and nitro groups, as well as halogen atoms and methylalkoxy
radicals. Aniline, toluidine and xylidine are particularly
preferred starting materials. Suitable amines are, for example,
aniline, o-toluidine, m-toluidine, p-toluidine, xylidine,
anisidine, core-halogenated aniline, m-nitroaniline, p-nitro-
." _ _
aniline and 4,4'-diamino diphenyl methane.
As- used herein, alkyl radicals (moieties) having 1 to 4
carbon atoms are methyl, ethyl, propyl, isopropyl, n-butyl,
ter.-butyl, sec-butyl and isobutyl. As used herein, alkoxy
radicals (moieties) having 1 to 4 carbon atoms are methoxy,
ethoxy, propoxy, isopropoxy, n-butyloxy, ter.-butyloxy, iso-
butyloxy and sec.-butyloxy. As used herein, alkylene radicals
(moieties) having up to 3 carbon atoms are ethylene, iso- `~
propylene and propylene. As used herein, halogen includes
bromine, fluorine, iodine and chlorine. ,~
As used herein, the phrase "up to 4 carbon atoms" includes
4 carbon atoms and the phrase "up to 3 carbon atoms" includes
3 carbon atoms.
The preferred alkanols are those having 1 to 4 carbon atoms,
such as, methanol, ethanol, propanol, butanol and isobutanol.
Methanol and ethanol have special importance.

11184~7
By way of summary, this invention involves a process for ~
~,
the production of an N-alkylarylamine by the reaction of an
arylamine with an alkanol in the gaseous phase at a temperatrure
of 180 to 400C. in the presence of a copper or copper oxide
catalyst on a silicate carrier. Excellent yields are obtained,
and there is essentially no production of any N,N-dialkylaryl-
amine by product (i.e., superb catalyst selectivity).

111~34~7
DETAILED DESCRIPTION OP TIIIS INVENTION !
As used herein, all percentages and ratios are on a
weight basis unless otherwise stated herein or otherwise obvious
herefrom to one ordinarily skilled in the art. The followiny
specific examples illustrate this invention, but do not restrict
~.;.
the scope thereof. ~J' A-
EXAMPLE 1
200 parts by weight of catalyst was placed in an electrically
heated solid bed reactor (diameter 26 mm, length 70 mm). The
o catalyst, in the form of cubes or pellets, consisted of copper
on a silicate carrier.
The catalyst was kept at 250C. and 29.4 parts by weight
of a methanol - aniline mixture (mole ratio l to l) was pumped
into the reactor.
The tarry time in the catalyst bed was 42 seconds.
T~e gaseous reaction mixture obtained was condensed. 26.7
parts by weight of condensate were obtained every hour. The ~_
condensate separated into an aqueous and an organic layer. --
The organic layer contained 21.4 parts by weight of
~ N-methyl aniline, 0.2 parts by weight of N,N-dimethyl aniline,
3 parts by weight of aniline and 0.2 parts by weight of methanol.
This corresponds to an aniline conversion of 86 percent. The '~-
yield of N-methylaniline, related to the converted aniline,
amounted to 97.7 percent. ~-
T~-

~184 ~7
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