Process for the preparation of alkylamines

Details Process for the preparation of alkylamines Process for the preparation of alkylamines

2000-09-25

2003-06-10

Davis, Brian J. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Amino nitrogen containing

C564S485000

Reexamination Certificate

active

06576796

ABSTRACT:

The present invention relates to a process for the preparation of alkylamines.
Alkylamines are starting materials for the preparation of surfactants, textile and flotation auxiliaries, bactericides, corrosion and foam inhibitors, additives for pharmaceuticals, and as antioxidants for fats and oils.
Alkylamines can be prepared by the hydrogenation of corresponding nitriles or nitro compounds, by the reductive amination of corresponding aldehydes and ketones and by the amination of corresponding alcohols.
The lower alkylamines (C
1
- to C
10
-alkylamines), such as the ethylamines, butylamines and isopropylamines, are prepared industrially in particular by the amination of the corresponding alcohol or of the corresponding carbonyl compound over metal catalysts, which are e.g. supported, under hydrogenating conditions (see e.g.: Ullmann's Encyclopedia of Industrial Chemistry, Vol. A 2, 5
th
Ed., page 4).
Alternatively, alkylamines can also be prepared over acidic phoshate catalysts from corresponding alcohols (see e.g. U.S. Pat. No. 4,582,904 (Air Products)).
A further alternative for the preparation of alkylamines consists in the addition of NH
3
or amines to olefins in the presence of acidic catalysts, such as zeolites (see e.g. EP-A-132 736), in the presence of basic catalysts, such as metal amides, in particular alkali metal amides and alkaline earth metal amides, (see e.g. B. W. Howk et al., J. Am. Chem. Soc. 76, page 1899ff (1954); R. Stroh et al., Angew. Chem. 69, 124ff (1957)), amides of subgroup IV (see e.g. D. Steinborn et al. (Z. Chem. 29 (1989), page 333ff) or alkali metal alkoxides, or in the presence of transition metal complex compounds (see e.g. U.S. Pat. No. 3,758,586).
However, to date this alternative has scarcely been used industrially.
The processes listed above for the preparation of alkylamines have the following disadvantages:
The use of alcohols (e.g. ethanol), aldehydes, ketones and nitriles as starting materials for the preparation of alkylamines is significantly less economical based on their prices than the use of corresponding olefins (e.g. ethene).
The use of olefins as starting material for the preparation of alkylamines is accordingly desirable, but has hitherto been burdened with the following disadvantages (cf. e.g.: M. Beller et al., Chem. Rev. 98, 675f (1998) 675; R. Taube, ‘Reaction with Nitrogen Compounds’ in B. Cornils and W. A. Hermann: ‘Applied Homogeneous Catalysis with Organometallic Compounds’, VCH Weinheim, 1996, pages 507 to 520, and E. Haak et al., Chemie in unserer Zeit (1999), 297 to 303, in particular the summary on p. 302):
aa) The addition, under basic and heterogeneous catalysis, of amines to olefins over metal oxides is possible, according to Kakuno et al. (J. Catal. 85 (1984), page 509ff), with primary and secondary alkylamines and conjugated dienes, such as butadiene or isoprene; the general use of NH
3
or monoolefins is not described.
ab) The addition, under weakly basic catalysis, of amines to olefins using alkali metal alkoxide as catalyst is, according to Beller et al. (Angew. Chem. 110 (1998), page 3571ff), successful in the case of aromatically conjugated amines and styrene as olefin component. In the case of NH
3
or monoolefin as starting material, the catalysts are inactive.
ac) In the case of the NaNH
2
- or KNH
2
-catalyzed addition of NH
3
to olefins, as is described e.g. in B. W. Howk et al., J. Am. Chem. Soc. 76 (1954), 1899-1902 and R. D. Closson et al., U.S. Pat. No. 2,750,417, the space-time yields of desired alkylamines are very low even at high temperatures and olefin pressures because of the low activity and solubility of the metal amide.
ad) G. P. Pez (U.S. Pat. Nos. 4,336,162 and 4,302,603) describes a solution to this problem by changing to the Rb and Cs amides or using a eutectic of NaNH
2
and KNH
2
. In the first case, industrial realization is precluded due to the extremely high price of the catalyst, and in the second case the space-time yields of desired alkylamines are still too low.
ae) Alkali metal monoalkylamides or alkali metal dialkylamides can be used as strong bases for the addition of olefins, such as ethylene, to amines with sufficient space-time yields, although in the presence of NH
3
immediate protolysis of the corresponding alkali metal alkylamide to give MNH
2
(M=alkali metal) occurs. This again has the disadvantages already listed above.
However, the alkali metal alkylamide-catalyzed addition of amines to olefins in the absence of NH
3
again has the disadvantage that relatively expensive amines have to be used as starting materials instead of low-cost ammonia.
b) Over acidic catalysts, such as zeolites, the addition of NH
3
to olefins, ammonia generally being used in a high excess based on the olefin, does not proceed in every case with such good selectivities and yields for a certain alkylamine as, for example, in the case of isobutene (see e.g. DE-A-36 34 247).
Thus, for example, M. Deeba et al. in Zeolites 10 (1990), page 794ff, and in Chem. Ind. 40 (1990), page 241ff, in the case of the reaction of ethylene and NH
3
over zeolites, and Gardner et al. in EP-A-200 923 in the case of the reaction of ethylene and NH
3
in the presence of NH
4
I, found predominantly monoethylamine, in addition to small amounts of diethylamine and very small amounts of triethylamine.
One solution would be the hydroamination of olefins with NH
3
in substoichiometric amount, although in this case poor selectivities based on the olefin are generally achieved and rapid deactivation of the catalyst results.
The hydroamination of olefins with secondary amines in the presence of acidic catalysts again generally proceeds in poorer yields and with poorer selectivities than the corresponding hydroamination with ammonia or primary amines.
c) The transition metal complex-catalyzed hydroamination of olefins is generally possible in good yields only with secondary alkylamines (e.g.: Brunet, Gazzetta Chimica Italiana, 127, 1997, pages 111 to 118, page 112, left-hand column).
It is an object of the present invention to find, while overcoming the disadvantages of the prior art, an alternative, economical and flexible process for the preparation of alkylamines which permits the preparation of a desired alkylamine or two or more desired alkylamines with a high space-time yield and selectivity.
We have found that this object is achieved by a process for the preparation of alkylamines which comprises, in a first process stage, reacting an olefin with ammonia, a primary amine and/or a secondary amine under hydroaminating conditions, and then, in a second process stage, reacting the resulting hydroamination product(s) under transalkylating conditions.
In a preferred embodiment of the process, in the balance of the feed materials olefin and ammonia, primary amine and/or secondary amine, only ammonia and olefin are consumed by establishing corresponding recycle streams of amines resulting from the first and/or second process stage to the feed of the first and/or second process stage.
Olefins or mixtures thereof which can be used in the process according to the invention are generally olefins of the formula
in which
R
1
, R
2
, R
3
, R
4
are hydrogen (H), C
1
- to C
20
-alkyl, C
2
- to C
20
-alkenyl, C
3
- to C
20
-cycloalkyl, C
5
- to C
8
-cycloalkenyl, C
6
- to C
20
-alkylcycloalkyl, C
6
- to C
20
-cycloalkylalkyl, aryl, C
7
- to C
20
-alkylaryl and C
7
- to C
20
-aralkyl, and
R
1
and R
3
can additionally together be a C
2
- to C
12
-alkylene chain.
Examples of such olefins are ethene, propene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 3-hexene, 1-octene, isooctene, 1-decene, styrene, stilbene, cyclopentene, cyclohexene, allene, 1,3-butadiene, isoprene and 4-vinyl-1-cyclohexene.
Primary and secondary amines or mixtures thereof which can be used in the process according to the invention are generally amines of the formula
in which
R
5
is hydrogen (H), C
1
- to C
20
-alkyl, C
2
- to C
20
-alkenyl, C
3
- to C
20
-cycloalkyl, alkoxyalkyl, aminoalkyl, monoalkylaminoalky

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