- 1 -
PROCESS FOR PREPARING ALKYLALKANOLAMINES
The present invention relates
synthesis of alkylalkanolamines
to a process for the
(subsequently referred
to as AAAs), in pa~ticular an improved process for
obtaining, in particular at the industrial level,
alkylalkanolamines of high purity, with high yields,
without the use of raw materials of epoxide type.
AAAs, and in particular alkylethanolamines, are
intermediate compounds which are important in the
chemical industry and in the pharmaceutical industry,
where they can be used as dispersing agents,
emulsifiers or surfactants or in the synthesis of
active ingredients. They are also used as a
neutralizing agent in water-based paints, or as a
corrosion inhibitor in lubricants or hydraulic fluids,
to cite only the most common applications .
According to the mode of preparation commonly used,
AAAs, and in parti cular alkylethanolamines, are
obtained by reacting primary or secondary amines with
an epoxi de, respectively ethylene oxide , as indicated
in the reaction below:
RR'NH +
+
/CH 2-CH~OH
R-N
\H2-CH~OH
- 2 -
These reactions are, for example, described in patent
applications FR 2 251 545 (BASF) or else FR 2 387 212
(Bayer) .
According to this reaction scheme, the secondary amines
thus result in N,N-dialkylethanolamines, while the
primary amines resul t in N-alkylethanolamines or in Nalkyldiet
hanolamines depending on the stoichiometric
ratio used .
However, and in particular in the case of primary
amines, the reaction most commonly results in a mixture
of alkylmonoethanolamine and alkyldiethanolamines which
are sometimes difficult to separate depending on the
nature of the alkyl group.
Moreover, this preparation mode results i n by-products
which are compounds from polyaddition of the epoxide
used, for example when ethylene oxide is used :
R-N
(CH2-CH2-0)- H
/ n
\cH2-CH2-0)-H
n'
It is also well known that proceeding in this manner
results i n AAAs, in particular alkylethanolamines,
which become colored during distillation and/or during
storage. This
conjugated
carbonyl ated
particularly
coloration is due to the presence of
unsaturated impurities and/or of
derivatives and can prove to be
bothersome for certain applicat~ons, in
particular in pai nts (white bases) .
Various treatment methods have been described for
limiting this problem of alkylethanolamine coloration.
- 3 -
Among these, mention may be made of those described in
patents and patent applications US 2004/0110988 (Air
Products), US 6291715 (BASF), EP 632013 (Union Carbide)
and EP 477593 (Atochem), to cite just some of them, and
in order to show the large number of studies carried
out in order to attempt to find a solution to this
coloration problem.
In particular, in order to inhibit the compounds
capable of introducing a coloration, one solution
consists in treating the reaction crude, or the
previously distilled AAA, with a reducing agent (such
as hydrogen, NaBH4 , and the like). This solution
therefore requires an additional treatment of the
reaction crude, which can prove to be expensive in
terms of energy expended and loss of yield .
There remains therefore, at this time, a need for a
process for the synthesis of AAAs, which can be readily
industrialized, which has good yields, which can do
without the use of raw materials that are dangerous or
difficult to use, and which generates only few or no
by-products, in particular by-products responsible for
the coloration of AAAs.
These objectives are totally or at least partly
achieved by virtue of the present invention, details of
which are given in the description which follows.
Thus, according to a first aspect, the subject of the
present invention consists of a direct synthesis
process which avoids handling compounds bearing an
epoxide function, in particular ethylene oxide, which
is an extremely inflammable and toxic liquefied gas,
said direct synthesis process, after distillati on,
resulting in AAAs, in particular alkylethanolamines, of
high purity which are colorless and storage-stable,
without any additional specific purification treatment .
- 4 -
More specifically, the present invention relates to the
process for preparing alkylalkanolamines of formula
(A) :
(A)
in which:
R1 represents a hydroxyalkyl radical, the alkyl part
being linear and containing two carbon atoms;
R2 is chosen from a hydrogen atom and a linear alkyl
radical containing two carbon atoms and substituted
with one or more hydroxyl (-OH) radicals;
Rand R', which may be identical or different, are each
chosen from a hydrogen atom, an alkyl, hydroxyalkyl,
alkoxy, alkylamine, dialkylamino or alkoxyalkyl
radical, where alkyl is a linear or branched
hydrocarbon-based chain containing from 1 to 10 carbon
atoms, preferably from 1 to 6 carbon atoms, and a
cycloalkyl radical containing from 3 to 9 carbon atoms,
with the restriction that R and R' cannot each
simultaneously represent a hydrogen atom;
or else
R and R' together form, with the carbon atom which
bears them, a saturated or totally or partially
unsaturated, mono-,
optionally comprising
bi- or
one or more
from oxygen, sulfur and nitrogen,
said process comprising a step of
in the presence of hydrogen and
polycyclic radical
heteroatoms chosen
reductive amination,
a catalyst, of a
carbonyl compound of formula (1) with a
hydroxyalkylamine of formula (2) :
- 5 -
0 y R'
R (1) (2)
in which R, R', R1 and R2 are as defined above.
In the present description, and unless otherwise
indicated,
the term alkyl radical is intended to mean: a linear or
branched, optionally substituted, hydrocarbon-based
radical containing from 1 to 10 carbon atoms,
preferably from 1 to 6 carbon atoms, or a cyclic
hydrocarbon-based radical containing from 3 to 9 carbon
atoms, preferably from 5 to 9 carbon atoms;
the term mono-, bi- or polycyclic radical is intended
to mean: a saturated or totally or partially
unsaturated, optionally substituted, mono-, bi- or
polycyclic radical optionally comprising one or more
heteroatoms chosen from oxygen, sulfur and nitrogen,
with a number of ring members of between 3 and 12 .
Preferably, said radical is monocyclic and comprises
from 3 to 9 ring members, preferably it comprises 5, 6
or 7 ring members.
In the preferred embodiments of the present invention,
the term alkyl is intended to mean: methyl, ethyl,
n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl,
tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl,
1, 2-dimethylpropyl, n-hexyl, isohexyl, sec-hexyl,
cyclopentylmethyl, n-heptyl, isoheptyl,
cyclohexylmethyl, n-octyl, isooctyl, 2-ethylhexyl and
n-decyl, preferably methyl, ethyl or propyl;
the term hydroxyalkyl is intended to mean:
hydroxymethyl, 1-hydro:x:yethyl, 2- hydroxyethyl, 1-
hydroxy-n-propyl,
propyl and
2-hydroxy-n-propyl,
1-(hydroxymethyl)ethyl,
3-hydroxy-npreferably
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hydroxyethyl, hydroxypropyl, more
2-hydroxyethyl and 2-hydroxy-n-propyl;
the term alkylamine is intended to mean :
2-ethylamino, 1,1-dimethylethyl- 2-amino,
amino, n-propyl-3-amino, n-butyl-4-amino,
amino , including arylamino, which is
substituted~ for example phenylamino;
preferably
methylamine,
n-propyl-2-
n-pentyl-5-
optionally
the term dialkylamino is intended to mean :
dimethylamino, di(2-ethyl )amino, di(l,l-dimethylethyl)-
2-amino , di(n-propyl)-2-amino, di(n-propyl) - 3-amino,
di(n-butyl)-4-amino, di(n-pentyl)-5-amino, N-(2-ethyl)N-
methylamino, N-(1,1-dimethylethyl)-N-methyl-2-amino,
N- (n-propyl) - N- methyl-2- amino, N- (n-propyl) - N- methyl-3-
amino, N-(n-butyl)-N-methyl-4-amino, N-(n-pentyl)-Nmethyl-
5-amino, N-(2-ethyl}-N-ethylamino, N-(1,1-
dimethylethyl)-N-ethyl-2-amino, N-{n-propyl)-N-ethyl-2-
amino, N-(n-propyl)-N- ethyl-3-amino, N-(n- butyl)-Nethyl-
4-amino and N-(n-pentyl)-N-ethyl-5-amino,
including diarylamino, which is optionally substituted,
for example diphenylamine;
the term cycloal kyl is intended to mean: cyclopropyl,
cyclobutyl, cyclopent y l , cyclohexyl, cycloheptyl and
cyclooctyl , preferably cyclopentyl and cyclohexyl.
Among the compounds of formula (1) , preference is given
to those chosen from:
ketones : acetone, hydroxyacetone, methyl ethyl ketone
(MEK), methyl propyl ketone, methyl isopropyl ketone ,
methyl isobutyl ketone, diethyl ketone, diisobutyl
ketone, tetralone, acetophenone, para-methyl
acetophenone, para-methoxy acetophenone, m-methoxy
acetophenone, 2-aminoacetophenone, 1-phenyl-3-butanone,
cyclobutanone, cyclopentanone, cyclohexanone,
benzophenone, 2-aminobenzophenone, 3-aminobenzophenone,
4-aminobenzophenone, 3,3 , 5-trimethylcyclohexanone, 2,6-
dimethylcyclohexanone, cycloheptanone and
cyclododecanone;
aldehydes :
n-butyraldehyde,
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acetaldehyde,
isobutyraldehyde,
propionaldehyde,
pivalaldehyde,
valeraldehyde, n-hexanal, 2-ethylhexanal, heptanals, in
particular n-heptanal, octanals, in particular
n-octanal, undecanals, benzaldehyde, paramethoxybenzaldehyde,
para-tolualdehyde,
phenylacetaldehyde, hydroxypivalaldehyde and furfural.
Among the compounds of formula (2), preference is given
to those chosen from primary or secondary
hydroxyalkylamines or di(hydroxyalkyl)amines, and in
particular those chosen
diethanolamine.
from monoethanolamine and
The process according to the present invention consists
of a reductive amination of aldehydes or of ketones
with a monohydroxyalkylamine or a dihydroxyalkylamine,
preferably without the addition of organic solvent,
performed according to a batch or semi-continuous
process, under heterogeneous catalysis (agitated bed of
catalyst) .
The process according to the present invention is also
preferably carried out with a carbonyl compound/amine
molar ratio (or MR in the rest of the present
disclosure) close to the stoichiometry, more preferably
with a slight excess of the carbonyl compound relative
to the amine .
Thus, and according to one preferred embodiment of the
process according to the present invention, the MR is
advantageously between 0.9 and 1.8, preferably between
1 . 0 and 1.5, for the monoalkylation of primary or
secondary amines, and the MR is advantageously between
1.8 and 3.6, preferably between 2.0 and 3.0, more
preferably between 2.1 and 2.5, for the dialkylation of
primary amines .
- 8 -
This process makes it possible to produce, according to
the operating conditions, various alkylalkanolamines,
as indicated on the following synthesis schemes, given
by way of illustration but which are not limiting in
nature, from monoethanolamine (MEoA) and diethanolamine
( DEoA) :
R'c/ R' @-!] H
H~NH2 + + H2 R'yN.............-.OH + ~0 II MEoA 0 R
R R'
~NH2 2 R'c/R' @ata] R'y
+ + H2 '('N.............-.OH + ~0
II
0
OH
H R'c/R' @-] R' ~
N + + H2 >-·"" + H20 H~ .............-.OH II
DEoA 0
OH
Examples of alkylalkanolamines that can thus be
obtained according to the process of the present
invention are , i n a
butylethanolamine (sBEA)
from monoethanolamine,
nonlimiting manner, N- secfrom
methyl ethyl ketone and
N-(n-heptyl)diethanolamine
(C7DEoA) from n- heptanal and from diethanolamine
(DEoA), N-(isopr opyl)ethanolamine from acetone and from
monoethanolamine (MEoA}, N-(n-butyl)diethanolamine from
n-butyral dehyde and from diethanolamine (DEoA}, and
N, N' -di-(n-butyl}ethanolamine from n-butyraldehyde and
from monoethanolamine (MEoA} .
The hydrogenation catalyst that can be used in the
process of the invention may be of any type known to
those skilled in the art who are specialists in the
field of organic compound. hydrogenation . It is
preferred to use any type of catalyst normally used for
- 9 -
catalytic hydrogenation reactions in a heterogeneous
medium.
Nonlimiting examples of such catalysts can be chosen
from hydrogenation catalysts based on metals from
groups 8, 9, 10 and 11 of the periodic table of
elements (IUPAC), preferably Ni-, Co- or Cu-based Raney
catal ysts, palladium (Pd/C type), and also copper
chromites,
catalysts.
and more particularly Raney nickel
Among the commercially available catalysts suitable for
the needs of the process according to the invention,
mention may be made, by way of nonlimiting examples , of
the nickel catalyst BLM 112 W (Evonik), Amperkat® SK-Ni
Fe Cr 4546 (H.C . Starck) and Cu-1955 {BASF Catalysts) .
It may be advantageous, or even desirable, to pretreat
the catalyst, before using it in the reductive
amination reaction according to the invention, said
pretreatment consisting of a prior reduction of said
catalyst under a hydrogen stream. This is generally the
case when the catalyst is sold in its oxidized form (in
the case of copper chromites of Cu-1955P type) or only
partially reduced form.
Such a pretreatment is recommended, or even essential,
when the defined reaction temperature for carrying out
the reductive amination according to the invention is
below the reduction temperature of said catalyst.
The process according to the present invention is
particularly suitable for preparing alkylalkanolamines
on the industrial level, in a batch or semi-continuous
system, the equipment being similar to that generally
used for hydrogenation reactions. Indeed, the process
according to the present invention is carried out under
a hydrogen pressure, generally of between atmospheric
pressure and
80 bar, and
50 bar.
- 10 -
150 bar, preferably between 5 bar
more particularly between 10 bar
and
and
The reaction temperature can vary to large extents
depending on the nature of the raw materials and of the
catalysts used, and is generally included within a
range of from 20°C to 180°C. For example, the reaction
temperature is preferably between 40°C and 100°C with
Raney nickel catalysts and preferably between 120°C and
160°C with copper chromites.
As indicated above, the hydroxylamines of formula 2,
and in particular monoethanolamine {MEoA) and
diethanolamine {DEoA), are used in anhydrous form or in
the form of commercial aqueous solutions. Because of
the melting point of anhydrous DEoA, the commercial
aqueous form, for example that which has a titer of
85%, is preferred for the needs of the process
according to the present invention.
The process according to the invention can be carried
out in a batch or semi-continuous system. However, when
the carbonyl compound of formula {1} is an aldehyde,
the process is advantageously carried out in a semicontinuous
system {addition of the aldehyde as it is
consumed), in order to control the selectivity .
Preferably, the process according to the invention is
carried out without solvent, in particular without
organic solvent, it being understood that the amines of
formula (2) can be used in an aqueous solution as
indicated above.
At the end o f the reductive amination reaction, after
sedimentati on of the catalyst and separation of the
l i quid crude, the catalyst can be reused as it is for
another reductive amination reacti on, i.e. another
- 11 -
reductive amination reaction according to the invention
can be carried out on the same catalyst heel.
Because of the process of the present invention, it is
not at all necessary to treat the reaction crude with a
reducing agent (such as hydrogen, NaBH4 , and the like)
in order to inhibit the compounds that may provide a
coloration, as is the case in the syntheses
conventionally carried out for preparing
alkylalkanolamines, in particular those using ethylene
oxide.
Thus, the process according to the present invention
has the advantage of being able to do without a
reducing treatment. The reaction crude is thus directly
used in a distillation reaction under reduced pressure,
making it possible to obtain colorless
alkylalkanolamines of high purity, the coloration of
which remains stable during storage.
By way of example, the color of the sBEA obtained
according to the process of the present invention is
less than 3 Pt-Co units. After 18 months of storage at
ambient temperature in glass packaging (in the dark) or
HOPE packaging, or 12 months of storage in a steel
drum, this lack of color (less than 3 Pt-Co units)
persists.
The color is measured using a spectrophotometric method
by means of a Dr Lange LTMl colorimeter according to
standard ISO 6271-2: 2004 (platinum-cobalt scale); the
color is thus expressed in Pt-Co units (equivalent to
Hazen or APHA units which are also often used) .
The process for preparing AAAs according to the present
invention thus makes it possible to be able to have
AAAs which ar.e colorless or have very little color,
whereas, because of their instability, the AAAs
- 12 -
currently availabl e on the market are generally sold
with specifications of about 50 Hazen, or even
100 Hazen .
The present invention is now illustrated by means of
the examples which follow and which have no limiting
purpose with regard to the scope of the present
invention, said scope being defined, moreover, by means
of the appended claims .
Example 1: Synthesis of N-(sec-butyl)ethanolamine
( sBEA)
N- (sec- butyl)ethanolamine is prepared from methyl ethyl
ketone and from monoethanolamine (MEoA), according to
the following reaction scheme:
+
MEllA
/'..c/
n
0
[c.a]
The main side reactions which can occur during this
reaction are the following:
a) Hydrogenation of the methyl ethyl ketone to give
methyl ethyl carbinol (B2):
~c/
II
@at~ ~c~
I
0 OH
b) Dismutati on of the monoethanolamine
diethanolamine (DEoA) and ammonia:
H
N
HO~~OH
DEoA
to give
- 13 -
c) Formation of sec-butylamine (B2A) by reductive
amination of the methyl ethyl ketone with ammonia:
~c/ @ata]
II
0
d) Reaction for self-condensation of the methyl ethyl
ketone, producing EAK (ethyl amyl ketone) and then EAC
(ethyl amyl carbinol):
2 ~c/
II
0
+ ~c~
I II
0
+
EAK
EAC
e) Dialkylation of the monoethanolamine corresponding
to the reaction of the sBEA with the methyl ethyl
ketone:
H
N ~~OH
@ala] '!' N
~~OH
daBEA
+ H:!O
The methyl ethyl ketone {MEK) used {supplier Arkerna)
has a standard commercial purity of 99 . 9% .
The monoethanolarnine (MEoA} used in its anhydrous form
(supplier : BASF) has a purity of greater than 99 . 7%.
The catalyst used in this example, Cu 1955 P {supplier:
BASF Catalysts), is a copper chromite packaged in
soluble sachets .
Detailed procedure
- 14 -
The tests are carried out in a 65 L autoclave equipped
with a stirring and gas/liquid dispersion system, with
a jacket for heating with steam and cooling with water,
with an internal coil for additional cooling of the
reaction medium and with pressure and temperature
regulators.
Step a): Preliminary reduction of the Cu 1955P
The Cu 1955P catalyst (2.3 kg in plastic bags of
"SecuBag" type) is charged to the autoclave. 34.8 kg of
MEK are introduced. The autoclave is flushed with
nitrogen, and then nitrogen is injected in order to
provide a pressure in the autoclave of approximately
2 bar.
Hydrogen is injected until a pressure of 13 bar is
reached at ambient temperature. The stirring and the
heating of the autoclave are then begun. When the
temperature reaches 80°C, the pressure is increased to
20 bar by injecting hydrogen.
The reduction of the catalyst begins at 125°C. The
hydrogen flow rate is limited to 5 Nm3 /h. The pressure
then decreases to 9 bar. At the end of reduction, the
pressure goes back up to 28 bar. The reaction medium is
kept for a further 30 min at 130°C under 28 bar of
hydrogen. After the stirring has been stopped and the
catalyst has been sedimented, the secondary butanol
formed is drained off.
Step b): Synthesis of sBEA
f i ve s uccessive tests are carried out on the catalyst
heel prepared in the previous step (tests A to E) .
23 kg of MEK and then approximately 18.4 kg of MEoA are
- 15 -
charged. Hydrogen is then injected until a pressure of
15 bar is reached.
The stirring and the heating of the autoclave are then
begun. The hydrogenation begins at 80°C. The
temperature is increased gradually but in such a way as
to maintain an instantaneous maximum flow rate of
hydrogen of 5 Nm3 /h.
For test A, the hydrogenation is carried out in
5 h 30 min at a temperature of 130°C, under a pressure
of 28 bar.
For tests B to D, the hydrogenation is carried out for
3 h 30 min at a maximum temperature of 130°C and
continued for 1 h 30 min at 135°C.
For test E, the hydrogenation is carried out in
5 h 30 min directly at a temperature of 135°C.
For the various tests A to E, at the end of
hydrogenation, the reaction medium is cooled to 90 oC
and then stirring is stopped. In addition, after
hydrogen degassing up to 1 bar, the catalyst is left to
sediment for at least 2 hours before the reaction crude
is drained off.
Results:
The conversions, selectivities and yields obtained for
each of the five tests are collated in table 1 below.
The conversion of MEoA is between 98.6% and 99.8% with
an sBEA selectivity with respect to MEoA of between
97. 5% and 98 . 2%, hence a crude molar yield of sBEA
relative t o the initial MEoA used of about 96% to 98%.
Test DC DC
MEoA MEK
A 99.8 98.0
B 99.8 98.0
c 98.6 98.0
D 98.7 98.0
E 99.0 96.0
Selectivity
MeoA (%)
- 16 -
Table 1
I Selectivity I MEK
B2A sBEA DEoA B2A BZ EAI< EAC
0.2 98.2 0 . 0 0.2 3.0 0.3 0.0
0 . 2 98.2 0.0 0.2 3.6 0.4 0.0
0.2 98.2 0.1 0.2 2.7 0.3 0 .0
0.2 98.2 0.0 0.2 3.2 0.3 0.0
0.2 97.5 0.0 0.2 3.7 0.3 0.0
(%) sBEA/MEoA
yield
sBEA (%)
95.2 98.0
94.3 98.0
95.4 96.8
94.7 96 .. 9
93.6 96.5
The average composition by weight of the crudes of the
five operations , determined by gas chromatography, is
given in table 2 below:
-- Table 2 --
Concentration (%)
H20 12.9
sec-butylamine 0.11
MEK 1. 30
sec-butanol 2 .50
MEoA 0.35
EAK 0.16
EAC 0.01
sBEA 81.3
DEoA 0.02
other organic impurities 1. 35
Dist i llation:
A single distillation operation is carried out on a
column of about twenty theoretical plates, using 206 kg
of the mixture of the five crudes above.
A preliminary distillation step at atmospheric pressure
makes it possible to extract the light products, such
- 17 -
as the residual MEK and the 82, and also the majority
of the water. The EAK and the EAC forming an azeotrope
with the water are also predominantly extracted in this
top fraction:
• temperature at top of column : 77°C - 99°C;
• temperature in the boiler: 104°C - 155°C;
• reflux ratio at the top of the column - 1 .
The distillate is a two-phase distillate. After
settling-out of this fraction of light products,
22.7 kg of an aqueous phase (Fl aq . } and 6.0 kg of an
organic phase ( F2 aq.) of compositions indicated in
table 3 below are recovered .
-- Table 3 --
Composition by weight Fl (aq.) Fl (org.) F2 'Pure' Final.
22.7 leg 6.0 leg 12.8 leg fraction heel.
137 .7 leg 16.4 kg
B2A o. 62 1. 09 0.15
MEK 7.63 14.30 0.32
BuOH 6.95 53.75 1. 26
Ethanolamine - 0.14 5.14 0.08
EAK 0.18 3.00 0.25 0.01
EAC 0.01 0.10 0.12
sBEA 0.61 1.07 49.2 99.89 85.23
oiethanolamine - - - - -
other orqanic impurities 0.69 2.75 0.83 0.09 14.66
water 83.30 23 . 60 42.71 0 .02 0.02
The distillation is then continued under reduced
pressure. The residual water is eliminated at the top
of the column and then the ' pure ' sBEA is recovered by
drawing off via a sidestream at a column height of
approximately 70% . The drawing off of the sBEA as
pasteurized makes it possible to concentrate the
residual MEoA at the top of the column.
- 18 -
• pressure at top of column: 60 mbar - 70 mbar;
• temperature at top of column: 34°C - 100°C;
• temperature at the level of the drawing off via a
sidestream: 101°C - 103°C;
• temperature in the boiler: 110°C - 128°C;
• reflux ratio at head of column - 10;
• reflux ratio at the level of the drawing off via a
sidestream - 1 to 2 .
12.8 kg of a fraction F2 and 137.7 kg of 1 pure 1 sBEA
having a purity of 99.9%, representing 82.1% of the
sBEA present in the initial charge of the boiler, are
thus recovered .
Taking into account the "hold-up" of the column, the
distillation yield is about 85%.
The high-purity sBEA thus prepared remains virtually
colorless (color less than 3 Pt-Co units) after more
than 18 months of storage.
Example 2:
(C70EoA)
Synthesis of N-(n-heptyl)diethanolamine
The n-heptyldiethanolamine is prepared from n-heptanal
and diethanolamine (DEoA).
Three synthesis operations (K, L, M) are carried out
successively on the same catalyst heel in a 2 L
stainless steel Sotelem reactor , using an Amperkat® SKNi
Fe Cr 4546 Ni/Raney catalyst (supplier H. C. Starck).
Test K
After charging 50 g of Amperkat catalyst to the
autoclave (with 95 g of water) and then flushing the
aut oclave with nitrogen, 391.3 g of 85% DEoA (i.e.
- 19 -
332.6 g net of DEoA corresponding to 3 . 16 mol) are
introduced using a pump.
Hydrogen is then injected until a pressure of 15 bar is
reached and then the mixture is heated at 90°C with
stirring and the hydrogen pressure is adjusted to
28 bar.
The heptaldehyde (supplier Arkema, purity 97%) is then
introduced using a pump at a flow rate of 350 g/h,
while at the same time injecting hydrogen so as to
maintain the pressure of 28 bar and while at the same
time maintaining the temperature of the reaction medium
at 90°C.
After the introduction of 487.5 g of heptaldehyde (i.e.
4.14 mol), the reaction medium is kept stirring at 90°C
and under 28 bar of hydrogen for a further 30 minutes.
The stirring is then stopped and the catalyst is left
to sediment for at least two hours, after hydrogen
degassing up to 1 bar.
The supernatant liquid reaction crude is then drawn off
via a filter (to remove the possible catalyst fines).
866.6 g of crude C7DEoA are thus recovered, the
composition by weight of which, determined by gas
chromatography (table 4), indicates a total absence of
residual heptaldehyde, the excess heptaldehyde relative
to the DEoA being mostly converted to n-heptanol.
Test L
The test is carried out according to the same procedure
as for test K, but by directly charging 395 g of 85%
DEoA (i . e. 335 . 8 g net of DEoA corresponding to
3. 19 mol) to the catalyst heel of test K kept in the
autoclave and by injecting an amount of 432.3 g
- 20 -
( 3. 67 mol) of heptaldehyde over the course of 1 hour
15 minutes. At the end of the reaction, 833.3 g of
crude C7DEoA are thus recovered, the composition by
weight of which, determined by gas chromatography, is
indicated in table 4.
Test M
The test is carried out according to the same procedure
as for test K, but by directly charging 401.1 g of 85%
DEoA (i . e. 340.9 g net of DEoA corresponding to
3. 24 mol) to the catalyst heel of test L kept in the
autoclave and by injecting an amount of 432 . 7 g
( 3 . 68 mol} of heptaldehyde over the course of 1 hour
15 minutes. At the end of the reaction, 837.3 g of
crude C70EoA are thus recovered, the composition by
weight of which, determined by gas chromatography, is
indicated in table 4 .
-- Table 4 --
Composition bv weight of the reaction crudes (%)
Test H,O Eleptaldebyde Heptanol DEoA C70EoA other
impurities
K 20 - 13.6 0. 7 63.3 2. 4
L 13.5 - 9.3 1.7 73.7 1.8
M 13.5 - 8.6 1.8 74 . 0 2.2
Conversion C7DEOA C7DEOA Heptanol Molar yield
of DEoA (t) selectivity selectivity selectivity of C7DEoA
Test with respect with respect with respect relative to
to DEoA (%) to to the DEoA
heptaldehyde heptaldehyde used (t)
(%) (%)
K 98.0 96 . 3 70.7 26.6 94.4
L 95.3 99.4 81.9 17 . 9 95 .5
M 95 .2 98 .4 82 .2 16 .6 94.9
- 21 -
After mixing of the three reaction crudes above, a
purification operation is carried out on a Sovirel
distillation column packed with Multiknit packing with
a height of 1 m.
After charging to the boiler of the column 2113 g of
the crude C7DEoA mixture, the latter is concentrated by
azeotropic extraction of the heptanol and of the water
at atmospheric pressure (temperature at top: 96-98 °C}
and then depletion of the water under a pressure of
50 mbar with a maximum temperature in the boiler at the
end of concentration of 150°C.
243.2 g of an organic fraction comprising 86.2% of
heptanol, 5.2% of water and 7.6% of organic impurities
and then 312.7 g of an aqueous phase comprising 99.5%
of water, 0.25% of heptanol and 0.25% of organic
impurities are thus recovered.
The composition of the heel
concentration is the following:
• Heptanol: 0 . 09%;
• DEoA: 1. 86%;
• Other organic impurities: ·1 . 60%;
• Water: 0.06%;
• C7DEoA: 96.4%.
(1509.3 g) after
By continuing the fractional distillation of this heel
in the same apparatus, under a pressure of less than
1 mbar and after separation of a DEoA-rich top
fraction, 1358 g of distilled C7DEoA are obtained at a
temperature at the top of the column of 137.0°C
137.5°C and wi th a maximum temperature in the boiler of
180°C.
- 22 -
The purity of this distilled C7 DEoA is 98. 7%, with a
residual DEoA content of 0.05%, a water content of
0.02% and a color of less than 3 Pt-Co units .
With a distillation yield of 89. 5%, the overall molar
yield of distilled C7DEoA is therefore about 85%
relative to the DEoA initially processed .
After 6 months of storage in a glass bottle, at ambient
temperature and in the dark, the color of the C7DEoA
thus prepared remains quasi- stable since it is equal to
only 5 Pt-Co units.
The following examples are carried out according to
similar procedures , with the raw materials being varied
as indicated.
Example 3: Synthesis of N- (isopropyl)ethanolamine
(IPAE) from acetone and MEoA according to a batch
process (sBEA type}
With an acetone/MEoA molar ratio of 1 . 05, an amount by
weight of Cu 1955P catalyst of 11% relative to the
acetone, a reaction temperature of ll0°C and under a
hydrogen pressure of 28 bar, total conversion of the
acetone is obtained. The conversion of the MEoA is
99.7% with an N-(isopropyl}ethanolamine selectivity of
98 . 5% , i.e . a crude molar yield of IPAE of 98 . 2%
relative to the MEoA processed.
Example 4: Synthesis of N-(n-butyl)diethanolamine
(BDEoA) from n-butyraldehyde and 85% DEoA according to
a semi- continuous process (C7DEoA type)
With an n- butyraldehyde/DEoA molar ratio of 1 . 04, an
amount by weight of Amperkat® SK- NiFeCr 4 54 6 catalyst
of 7 . 3% relative to the DEoA, and a semi-continuous
introduction of the n-butyraldehyde over the course of
- 23 -
1 hour 15 minutes, while maintaining the reaction
temperature at 65°C- 70°C, under a hydrogen pressure of
28 bar, complete conversion of the N-butyraldehyde is
obtained. The conversion of the DeoA is 94% with an
N-(n-butyl)diethanolamine selectivity of 98 . 3%, hence a
crude molar yield of BDEoA of 92 . 4% relative to the
DEoA processed.
The BDAoE is extracted, by fractional distillation of
the reaction crude, under a pressure of 25 mbar and at
a temperature at the top of the column of 145°C
146°C. The purity of the BDEoA is 99.2% with a
distillation yield of 91%. The color of the BDEoA thus
prepared is less than 3 Pt-Co uni ts on leaving the
disti llation, and 2 5 Pt-Co units after 18 months of
storage in a glass bottle at ambient temperature and in
the dark .
Example 5 : Synthesis of N,N ' -di-(n-butyl)ethanolamine
(DBEoA) from n-butyraldehyde and MEoA according to a
semi-continuous process (C7DEoA type)
With a butyraldehyde/MEoA molar ratio of 2 . 16, an
amount by weight of Amperkat SK-NiFeCr 4546 catalyst of
10.6% rel ative to the MEoA, and a semi-continuous
introduction of the butyraldehyde over the course of
1 hour 50 minutes, while maintaining the reaction
temperatur e at 70°C, under a hydrogen pressure of
28 bar, complete conversion of the butyraldehyde and of
the MEoA is obtained. The crude mol ar yield of DBEoA is
79% relative to the MEoA processed; the two main byproducts
are N- (n-butyl)ethanolamine and n-butanol.
The DBEoA is extracted, by fractional distill ation of
the reaction crude, under a pressure of 46 mbar and at
a temperature at the top of the column of 130 . 5°C. The
purity of the DBEoA is 99.8% with a distillation yiel d
of 86% and a color of less than 3 Pt-Co units.

- 24 -
CLAIMS
1. A process for preparing alkyl alkanolamines of
formula (A) :
(A)
in which :
R1 represents a hydroxyalkyl radi cal , the alkyl
part being linear and containing two carbon atoms ;
R2 is chosen from a hydrogen atom and a linear
alkyl radical containing two carbon atoms and
substituted with one or more hydroxyl ( -OH)
radicals;
Rand R' , which may be identical or different, are
each chosen from a hydrogen atom, an alkyl,
hydroxyalkyl, alkoxy, alkylamine, dialkylamino or
a l koxyal kyl radical, where alkyl is a l inear or
branched hydrocarbon-based chain containing from 1
to 10 carbon atoms, preferably from 1 to 6 carbon
atoms , and a cycloalkyl radical containing from 3
to 9 carbon atoms, with the restriction that R and
R' cannot each simultaneously represent a hydrogen
atom;
or else
R and R' together form, with the carbon atom which
bears them, a saturated or totally or partial ly
unsaturated, mono-, bi- or polycyclic radical
optionally comprising one or more heteroatoms
chosen from oxygen, sulfur and nitrogen,
said process comprising a step of reductive
amination, in the presence of hydrogen and a
catalyst, of a carbonyl compound of formula ( 1)
with a hydroxyalkylamine of formula (2):
- 25 -
0 y R'
R (1) (2)
in which R, R', R1 and R2 are as defined above.
2. The process as claimed in claim 1, in which the
compound of formula (1) is chosen from acetone,
hydroxyacetone, methyl ethyl ketone (MEK), methyl
propyl ketone, methyl isopropyl ketone, methyl
isobutyl ketone, diethyl ketone, diisobutyl
ketone, tetralone, acetophenone, para-methyl
acetophenone, para-methoxy acetophenone, m-methoxy
3.
acetophenone, 2-aminoacetophenone, 1-phenyl-3-
butanone, cyclobutanone, cyclopentanone,
cyclohexanone, benzophenone, 2-aminobenzophenone,
3-aminobenzophenone, 4-aminobenzophenone, 3,3,5-
trimethylcyclohexanone, 2,6-dimethylcyclohexanone,
cycloheptanone, cyclododecanone, acetaldehyde,
propionaldehyde, n-butyraldehyde,
isobutyraldehyde, pivalaldehyde, va.leraldehyde,
n-hexanal,
particular
2-ethylhexanal, heptanals, in
n-heptanal, octanals, in particular
n-octanal, undecanals, benzaldehyde, paramethoxybenzaldehyde,
para-tolualdehyde,
phenylacetaldehyde, hydroxypivalaldehyde and
furfural.
The process as claimed in claim 1,
compound of formula (2) is
monoethanolamine and diethanolamine.
in which the
chosen from
4. The process as claimed in any one of the preceding
claims, in which the compound of formula (A) is
N-sec-butylethanolamine (sBEA}, obtained from
methyl ethyl ketone and from monoethanolamine,
N-(n-heptyl)diethanolamine (C7DEoA) obtained from
- 26 -
n-heptanal and from diethanolamine (DEoA),
N-(isopropyl)ethanolamine obtained from acetone
and from monoethanolamine (MEoA),
N-(n-butyl)diethanolamine obtained from
n-butyraldehyde and from diethanolamine (DEoA),
and N,N'-di-(n-butyl)ethanolamine obtained from
n-butyraldehyde and from monoethanolamine (MEoA).
5. The process as claimed in any one of the preceding
claims, in which the catalyst is chosen from
hydrogenation catalysts based on metals of groups
8, 9, 10 and 11 of the periodic table of elements
(IUPAC), preferably Ni-based, Co-based or Cu-based
Raney catalysts, palladium ( Pd/C type), and also
copper chromites,
nickel catalysts.
and more particularly Raney
6 . The process as claimed in any one of the preceding
claims, in which the hydrogen pressure is between
atmospheric pressure and 150 bar, preferably
between 5 bar and 80 bar, and more particularly
between 10 bar and 50 bar.
7. The process as claimed in any one of the preceding
claims, in which the reaction temperature is
included in a range of from 20°C to 180°C.
8. The process as claimed in any one of the preceding
claims, which is carried out in a batch or semicontinuous
system, preferably in a semi-continuous
system, when the carbonyl compound of formula {1)
is an aldehyde.
9 . The process as claimed in any one of the preceding
claims, in which the reaction crude is used in a
distillation operation.
- 27 -
10. The process as claimed in any one of t he preceding
clai ms, characterized in that it is .carri ed out
without o r ganic solvent.