Method for synthesizing an omega-amino acid or ester from a monounsaturated
fatty acid or ester
The work which led to this invention received financial support from the
European Union as part of Framework Program 7 (FP712007-2013) under
project number 24171 8 EUROBIOREF.
The invention is directed to a process for synthesizing w-amino-alkanoic acids
or their esters from unsaturated natural fatty acids, proceeding via an wunsaturated
nitrile intermediate compound.
The polyamides industry uses a whole range of monomers consisting of longchain
w-amino acids, normally called Nylon, which are characterized by the
length of methylene chain (-CH2), separating two -CO-NH- amide functions.
Known accordingly are Nylon-6, Nylon 6-6, Nylon 6-10, Nylon 7, Nylon 8, Nylon
9, Nylon 1 1, Nylon 13, etc.
These monomers are manufactured, for example, by a chemical synthesis route
using, in particular, as starting material, C2 to C4 olefins, cycloalkanes or
benzene, but also castor oil (Nylon 1 I), erucic oil or lesquerolic oil (Nylon 13),
etc.
The current development with regard to the environment is resulting, in the
fields of energy and chemistry, in favoring the development of natural raw
materials originating from a renewable source. This is the reason why some
studies have been commenced to develop, industrially, processes which use
fatty acidslesters as a raw material for manufacturing these monomers.
There are only a few industrial examples of this type of approach. One of the
rare examples of an industrial process utilizing a fatty acid as raw material is
that of the manufacture, from the ricinoleic acid extracted from castor oil, of 11-
aminoundecanoic acid, which forms the basis for the synthesis of Rilsan 1 I@.
This process is described in the work "Les Procedes de Petrochimie" by
A. Chauvel et al., published in Editions TECHNIP (1 986). I I -Aminoundecanoic
acid is obtained in a number of steps. he first involves methanolysis of the
castor oil in basic medium, producing methyl ricinoleate, which is subsequently
subjected to pyrolysis to give heptanaldehyde on the one hand and methyl
undecylenate on the other. The latter is converted to acid form by hydrolysis.
The acid formed is subsequently subjected to hydrobromination to give the wbrominated
acid, which is converted by amination to I I-aminoundecanoic acid.
The principal studies have related to the synthesis of 9-aminononanoic acid,
which is the precursor of Nylon 9, from oleic acid of natural origin.
With regard to this particular monomer, it is possible to cite the work "n-Nylons,
Their Synthesis, Structure and Propertiesn - 1997, published by J. Wiley and
Sons, in which section 2.9 (pages 381 to 389) is devoted to 9-Nylon. This article
summarizes the accomplishments and studies carried out on the subject.
Mention is made therein, on page 381, of the process developed by the former
Soviet Union, which led to the commercialization of Pelargon@. Mention is also
made therein, on page 384, of a process developed in Japan that uses oleic
acid originating from soybean oil as starting material. The corresponding
description refers to the work by A. Ravve "Organic Chemistry of
Macromolecules" (1 967), Marcel Dekker, Inc., in which section 15 is devoted to
polyamides, referring to the existence of such a process on page 279.
In order to be fully informed with regard to the state of the art on this subject, it
is necessary to cite the many articles published by E. H. Pryde et al. between
1962 and 1975 in Journal of the American Oil Chemists' Society - "Aldehydic
Materials by the Ozonization of Vegetable Oils" Vol. 39 pages 496-500; "Pilot
Run, Plant Design and Cost Analysis for Reductive Ozonolysis of Methyl
Soyate" Vol. 49 pages 643-648; and R.B. Perkins et al. "Nylon-9 from
Unsaturated Fatty Derivatives: Preparation and Characterization", JAOCS, Vol.
52 pages 473-477. It should be noted that the first of these articles also refers,
on page 498, to prior studies carried out by Japanese authors: H. Otsuki and
H. Funahashi.
To summarize this part of the state of the art concerning this type of synthesis
of "Nylon 9" from vegetable oils, a description may be given of the simplified
reaction mechanism below, applied to the oleic ester, which is extracted from
the oils by methanolysis:
Reductive ozonolysis
H3C-(CH2)7-CH=CH-(CH2)7-COOCH3 + (03H, 2) +
HOC-(CH2)7-COOCH3 + H3C-(CH2)7-COH
Reductive amination
HOC-(CH2)7-COOCH3 + (NH3, Hz) + H2N-(CH2)8-COOCH3+ H20
Hydrolysis
H2N-(CH2)s-COOCH3 +Hz0 + H2N-(CH2)8-COOH + CH30H
This route, though very attractive from a reaction standpoint, nevertheless
exhibits a substantial economic disadvantage arising from the production,
during the first step, of a long-chain aldehyde (9 carbon atoms in total) that has
virtually no derivable value, particularly in the polyamide polymers industry.
UK patent No. 741,739, for its part, describes the synthesis of this same acid
from oleic acid, but using the oleonitrile route. The simplified reaction scheme of
this process is that below. An analogous route is cited in the aforementioned
article by R.B. Perkins et al., page 475.
H3C-(CH2)7-CH=CH-(CH2)7-COOH+ NH3 +
H3C-(CH2)7-CH=CH-(CH2)7-CN + 2 H20
H3C-(CH2)7-CH=CH-(CH2)7-CN + (03 + H20) +
H3C-(CH2)7-COOH+ CN-(CH2)7-COOH
CN-(CH2)7-COOH + 2 H2 + H2N-(CH2)8-COOH
This synthesis leads to pelargonic acid, H3C-(CH2)7-COOHa, s a by-product.
The aim of the present invention is to provide a new process for synthesizing a
whole range of w-amino-alkanoic acids or their esters from unsaturated natural
fatty acids.
The problem is therefore to find a process for synthesizing various w-amino
acids of formula H2N-(CH2),-COOH (and their polymers) in which n is between
3 and 14 from renewable raw materials (very widely available and therefore
relatively inexpensive) that is simple to implement while avoiding, on the one
hand, the environmental constraints set out above and, on the other hand, the
economic disadvantages caused by the by-products of the reactions.
The proposed solution involves working from raw materials consisting of
natural, long-chain, unsaturated fatty acids, converting them, in a first stage,
into w-unsaturated nitriles, and then, in a second stage, "reinserting" a
carboxylic acid function into the compound by acting on the terminal double
bond of the w-unsaturated nitrile, by a cross metathesis reaction with an
acrylate compound.
A natural fatty acid is an acid from the plant or animal spheres, including algae,
more generally from the plant kingdom, which is therefore renewable. This acid
will comprise at least one olefinic unsaturation, the location of which in position
x relative to the acid group (delta x), and comprising at least 10 and preferably
at least 14 carbon atoms per molecule, will determine the formula of the final wamino
acid.
Examples of such acids include the CIO acids, obtusilic (cis-4-decenoic) acid
and caproleic (cis-9-decenoic) acid, the C12 acids, lauroleic (cis-9-dodecenoic)
acid and linderic (cis-4-dodecenoic) acid, the C14 acids, myristoleic (cis-9-
tetradecenoic) acid, physeteric (cis-5-tetradecenoic) acid and tsuzuic (cis-4-
tetradecenoic) acid, the C16 acid, palmitoleic (cis-9-hexadecenoic) acid, the
C18 acids, oleic (cis-9-octadecenoic) acid, elaidic (trans-9-octadecenoic) acid,
petroselinic (cis-6-octadecenoic) acid, vaccenic (cis-I I-octadecenoic) acid and
ricinoleic (12-hydroxy-cis-9-octadecenoic) acid, the C20 acids, gadoleic (cis-9-
eicosenoic) acid, gondoic (cis-I I-eicosenoic) acid, cis-5-eicosenoic acid and
lesquerolic (1 4-hydroxy-cis-I I -eicosenoic) acid, and the C22 acids, cetoleic
(cis-I I-docosenoic) acid and erucic (cis-1 3-docosenoic) acid.
These various acids are obtained from vegetable oils extracted from a variety of
oil-bearing plants, such as sunflower, oilseed rape, castor oil plant, bladderpod,
olive, soya, palm tree, avocado, sea buckthorn, coriander, celery, dill, carrot,
fennel, Camelina, and Limnanthes alba (meadowfoam).
They are also obtained from the terrestrial or marine animal worlds, and, in the
latter case, in the forms equally of fish, of mammals, and of algae. In general
they are fats originating from ruminants, from fish such as cod, or from marine
mammals such as whales or dolphins.
The invention is directed to a process for synthesizing an w-amino acid (ester)
of formula R300C-(CH2),-CH2NH2, in which R3 is H or a n-butyl radical and q
is an integral index of between 2 and 13, from a monounsaturated fatty acid
(ester) of formula (R1-CH=CH-(CH2),-COO)&, in which x represents 1, 2 or 3,
R1 is H or a hydrocarbon radical comprising from 4 to 11 carbon atoms and,
where appropriate, a hydroxyl function, R2 is H or an alkyl radical comprising
from 2 to 4 carbon atoms, and may contain one or more heteroatoms, and p is
an integral index of between 2 and 11, comprising a reaction step of
ammoniation, leading to the conversion of the carbonyl function to a nitrile
function, characterized in that:
- in a first stage, the unsaturated fatty acidlester is converted into an wunsaturated
nitrile of formula CH2=CH-(CH2),-CN in two successive steps (in
any order) of ethenolysis and ammoniation, and then
- in a second stage, this w-unsaturated nitrile is converted into an ester nitrile of
formula R300C-CH=CH-(CH2),-CN, in which R3 is n-butyl, by a cross
metathesis reaction of the w-unsaturated nitrile with an acrylate of formula
CH2=CH-COOR3, with a catalyst of formula (I),
(1)
and then
- in a third stage, the ester nitrile is hydrogenated to w-amino acid (ester) of
formula ROOC-(CH2),-CH2NH2,
The reaction procedure is, then, as follows:
First stage:
R1-CH=CH-(CH2),-COOH + CH*=CH~
CH2=CH-(CH2),-COOH + CH2zCH-Rq
CH2=CH-(CH2)p-COOH + NH3 3 CH2=CH-(CH2)p-CN+ 2 H20
or, inverting the order of the reactions,
R1-CH=CH-(CH2),-COOH + NH3 3 R1-CH=CH-(CH2),-CN +2 H20
R1-CH=CH-(CH2),-CN + CH2=CH2G CH2=CH-(CH2)p-CN+ CH2=CH-R1
Second stage:
CH2=CH-(CH2),-CN + CH2=CH-COOR3 e
R300C-CH=CH-(CH2),-CN + CH2=CH2
Third stage:
R300C-CH=CH-(CH2)p-CN + 3 H23
R300C-(CH2)q-CH2NH2.
In this embodiment of the process, q is equal to p+2.
Applied to oleic acid, the procedure becomes
First stage:
CH3-(CH2)7-CH=CH-(CH2)7-COOH+ CH2=CH2U
CH2=CH-(CH2)7-COOH + CH~ZCH-(CH~)~-CH~
CH2=CH-(CH2)7-COOH + NH3 3 CH2=CH-(CH2)7-CN + 2 H20
or, inverting the order of the reactions,
CH3-(CH2)7-CH=CH-(CH2)7-COOH+ NH3 3
CH3-(CH2)7-CH=CH-(CH2)7-C+N2 H20
CH3-(CH2)7-CH=CH-(CH2)7-CN + CH2=CH2 e
CH2=CH-(CH2)7-CN + CH2=CH-(CH2)7-CH3
Second stage:
CHZ=CH-(CH~)~-C+N C H2=CH-COOR3 U
R300C-CH=CH-(CH2)7 -CN +
CH2=CH2
Third stage:
second variant: R300C-CH=CH-(CH2)7-CN+ 3 H2+ R300C-(CH2)9-CH2NH2
The only "by-products" formed are a long-chain a-olefin, possibly comprising a
hydroxyl function.
In a simplified variant embodiment of the process of the invention, a step may
be saved by synthesizing the nitrile of the fatty acidlester, of formula R1-
CH=CH-(CH2),-CN, in the first stage, by ammoniation of the original acidlester,
then by subjecting the latter to cross metathesis with an acrylate R300CCH=
CH2 to give the ester nitrile of formula R300C-CH=CH-(CH2),-CN, which
will be subsequently hydrogenated to R30OC-(CH2),+2-CH2NH2.
In another variant of the process, using hydroxyl-containing fatty acids as raw
material, such as ricinoleic acid and lesquerolic acid, which conform to the
general formula R1-CH=CH-(CH2)p-COOHw ith Rqb eing CH3-(CH2)5CHOH-CH2-
and p being, respectively, 7 and 9, the acid in its methyl ester form is subjected
to pyrolysis, giving an w-unsaturated ester of formula CH2=CH-(CH2),+,-
COOCH3, which is converted, directly or proceeding via the acid, into an wunsaturated
nitrile of the same kind as the intermediate compound obtained at
the end of the first stage of the process described above. This variant therefore
involves, for these particular fatty acids, replacing the initial ethenolysis by a
pyrolysis.
The following stages of the process are analogous to those of the process
described above. They therefore result in compounds of formula R300C-
(CH2),-CH2NH2 in which q is equal to p+3.
Accordingly, in preferred embodiments of the invention:
- in the first stage the ethenolysis of the acid (ester) is carried out first, followed
by the ammoniation of the w-alkenoic acid;
- in the first stage, the ammoniation of the acid (ester) is carried out first,
followed by the ethenolysis of the nitrite of the starting fatty acid;
- in the first stage the pyrolysis of the hydroxyl-containing fatty acid (ester) is
carried out first of all, followed by the ammoniation of the w-alkenoic acid (ester)
obtained from the pyrolysis;
- in the first stage the ammoniation of the acid (ester) is carried out, without
continuing to the ethenolysis reaction;
- in the second stage, the product obtained from the first stage is subjected to a
cross metathesis reaction with the acrylate compound;
- the compound obtained from the second stage is subjected to a
hydrogenation.
In one particular embodiment of the invention, in the formula (R1-CH=CH-
(CH2),-COO),R2, x represents 3 and the radical R2 is CH2-CH-CH2, or x
represents 2 and R2 is CH2-CH-CH20H or CH2-CHOH-CH2.
Metathesis reactions have been known for a long time, although their industrial
applications are relatively limited. With regard to their use in the conversion of
fatty acids (esters), reference may be made to the article by J.C. Mol "Catalytic
metathesis of unsaturated fatty acid esters and oil" in Topics in Catalysis of
unsaturated fatty esters and oil Vol. 27, Nos. 1-4, February 2004 (Plenum
Publishing).
Catalysis of the metathesis reaction has been the subject of a very large
number of works, and the development of sophisticated catalytic systems.
Mention may be made, for example, of the tungsten complexes developed by
Schrock et al. (J. Am. Chem. Soc. 108 (1986) 2771 or Basset et al., Angew.
Chem., Ed. Engl. 31 (1992) 628. More recently, catalysts have appeared which
are referred to as Grubbs catalysts (Grubbs et al., Angew. Chem., Ed. Engl. 34
(1 995) 2039 and Organic Lett. 1 (1999) 953), which are ruthenium-benzylidene
complexes. This relates to homogeneous catalysis. Heterogeneous catalysts
have also been developed that are based on metals such as rhenium,
molybdenum, and tungsten, deposited on alumina or silica.
Lastly, studies have been carried out for the production of immobilized
catalysts, these being catalysts in which the active principle is that of the
homogeneous catalyst, particularly the ruthenium-carbene complexes, but is
immobilized on an inert support. The objective of these studies is to increase
the selectivity of the cross metathesis reaction with regard to competing
reactions such as the "homometathesis" reactions between the reactants
brought together. The studies relate not only to the structure of the catalysts but
also to the effect of the reaction mixture and the additives that may be
introduced.
The cross metathesis reaction with ethylene during one of the steps of the first
phase may be carried out with any active and selective metathesis catalyst, and
is preferably conducted at a temperature of between 20 and 100°C under a
pressure of 1 to 30 bar in the presence of a conventional metathesis catalyst, of
ruthenium type, for example. The reaction time is selected according to the
reactants employed and so as to reach as close as possible to equilibrium of
the reaction. The reaction is carried out under ethylene pressure. It may be
carried out directly on the oil, the ester, and on the fatty acid.
The ruthenium catalysts are selected preferably from charged or uncharged
catalysts of general formula:
(X1)a (X2)bRu(carbene C) (Ll)c(L2)d
in which:
a, b, c and d are integers, with a and b being 0, 1 or 2, and c and d being 0, 1,
2, 3 or 4;
XI and X2, which are identical or different, each represent a charged or
uncharged unidentate or multidentate ligand; examples include halides, sulfate,
carbonate, carboxylates, alkoxides, phenoxides, amides, tosylate,
hexafluorophosphate, tetrafluoroborate, bis-triflylamide, tetraphenylborate, and
derivatives. XI or X2 may be bonded to Y1 or Y2 or to the (carbene C) so as to
form a bidentate ligand (or chelate) on the ruthenium; and
L1 and L2, which are identical or different, are electron-donating ligands, such
as phosphine, phosphite, phosphonite, phosphinite, arsine, stilbine, an olefin or
an aromatic, a carbonyl compound, an ether, an alcohol, an amine, a pyridine or
derivative, an imine, a thioether or a heterocyclic carbene.
L1 or L2 may be bonded to the "carbene C" so as to form a bidentate ligand or
chelate.
The "carbene C" may be represented by the general formula: C-(R1)-(R2), for
which R1 and R2 are identical or different, such as hydrogen or any other
saturated or unsaturated, cyclic, branched or linear, or aromatic hydrocarbonyl
group. Examples include complexes of ruthenium with alkylidenes, or with
cumulenes, such as vinylidenes, Ru=C=CHR, or allenylidenes,
Ru=C=C=CRI R2, or indenylidenes.
A functional group which enhances the retention of the ruthenium complex in
the ionic liquid may be grafted onto at least one of the ligands XI, X2, L1 and
L2, or onto the carbene C. This functional group may be charged or uncharged,
such as, preferably, an ester, an ether, a thiol, an acid, an alcohol, an amine, a
nitrogen-containing heterocycle, a sulfonate, a carboxylate, a quaternary
ammonium, a guanidinium, a quaternary phosphonium, a pyridinium, an
imidazolium, a morpholinium or a sulfonium.
The cross metathesis reaction with butyl acrylate is carried out under very wellknown
conditions. The reaction temperature is between 20 and 100°C,
generally at atmospheric pressure, to allow easy release of the ethylene in the
presence of a ruthenium-based catalyst of formula (I) as given above.
The reaction scheme of the synthesis of nitriles from acids, which is well-known
to the skilled person, may be summarized as follows:
R-COOH + NH3 + [R-COO-NH;] + [R-CONH2] + H20 .) RCN + H20
This scheme applies both to natural fatty acids (esters) and to w-unsaturated
fatty acids.
The process may be carried out batchwise in liquid or gas phase, or
continuously in gas phase. The reaction is carried out at a high temperature
> 250°C in the presence of a catalyst, which is generally a metal oxide and
most commonly zinc oxide. Continuous removal of the water formed with
entrainment, moreover, of the unreacted ammonia, enables rapid completion of
the reaction.
The pyrolysis reaction employed in the variant of the process is carried out on
the ester form of the relevant hydroxyl-containing fatty acid, in general the
methyl ester. The reaction is carried out at high temperature, of between 400
and 750°C and preferably between 500 and 600°C, in the presence of
superheated steam.
The pyrolysis reaction, applied to methyl ricinoleate, corresponds to the
following procedure:
CH3-(CH2)5CHOH-CH2-CH=CH-(CH2)7-COOCH+3 A 3
CH3-(CH2)5CH0 + CH2=CH-(CH2)8-COOCH3
It is followed by an ammoniation:
CHZ=CH-(CH~)~-COOC+H N~H s + CH2=CH-(CH2)8-CN+ 2 H20.
The step of synthesizing the fatty w-amino acids (esters) from the fatty nitrile
esters involves a conventional hydrogenation. There are many catalysts, though
preference is given to using Raney nickels and cobalts. To promote the
formation of primary amine, a partial pressure of ammonia is employed. Lastly,
the reduction of the nitrile function to primary amine is well known to the skilled
person.
In the process of the invention, the fatty acid may be treated either in its acid
form or in its ester form, including triglyceride or diglyceride forms. The entirely
commonplace switch from one form to the other, by methanolysis, esterification
or hydrolysis, does not constitute a chemical conversion in the sense of the
process.
All of the mechanisms detailed below illustrate the synthesis of the acids, in
order to facilitate the account. However, metathesis is also effective with an
ester and is even more effective, since the medium is generally more
anhydrous. In the same way, the schemes illustrate reactions with the trans
isomer of the acids (or esters); the mechanisms are equally applicable to the cis
isomers.
The reaction mechanism of this reaction is illustrated by scheme 1 below.
Scheme 1
RvmCOOR p
In the scheme above, q = p+2.
The implementational variant of the process of the invention, applied to
hydroxyl-containing unsaturated fatty acids, is illustrated by scheme 2 below.
'a'
Scheme 2
p=7 : ricinoleic ester
p=9 : lesquerolic ester
The invention relates, moreover, to the amino acid or amino ester of renewable
origin of general formula NH2CH2-(CH2),-COOR, with R being either H or a
butyl radical.
Amino acids or amino esters of renewable origin are amino acids or amino
esters which comprise carbon of renewable origin.
By employing the process of the invention it will be possible to synthesize a
whole range of w-amino acids.
4-Aminobutanoic acid is obtained from eicosenoic acid.
6-Aminohexanoic acid is obtained from obtusilic, linderic and tsuzuic acids.
7-Aminoheptanoic acid is obtained from physeteric acid.
8-Aminooctanoic acid is obtained from petroselinic acid.
I I -Aminoundecylenic acid is obtained from lauroleic, caproleic, myristoleic,
palmitoleic, oleic, elaidic, ricinoleic and gadoleic acids.
12-Aminododecylenic acid is obtained from ricinoleic and lesquerolic acids.
13-Aminotridecylenic acid is obtained from vaccenic, gondoic, cetoleic and
lesquerolic acids.
15-Aminopentadecylenic acid is obtained from erucic acid.
The invention is illustrated by the examples which follow.
Example 1
This example illustrates the first step of ethenolysis of methyl oleate according
to the process that is the subject of the invention. For this reaction, the complex
catalyst [RuCI2(=CHPh)(lMesH2)(PCy3)is] used, whose formula (A) is given
below. The reaction is carried out in CH2C12, at a concentration of 0.05 M methyl
oleate and 0.2 M ethylene, at a temperature of 55°C and at atmospheric
pressure, and for 6 hours, in the presence of the catalyst at a concentration of
5 mot% relative to the methyl oleate. The yields are determined by
chromatographic analysis. It is possible to measure a yield of methyl 9-
decenoate, CH2=CH-(CH2)7-COOCH3, and of I-decene of 55 mot%.
Catalyst of formula (A)
P h
Formula (A)
Example 2
This example illustrates the second step, of ammoniation, converting the 9-
decenoic acid obtained after hydrolysis of the ester from the first step into nitrile
of formula CN-(CH2)7-CH=CH2.
The ammoniation reaction of 9-decenoic acid (3.5 g) to form the w-unsaturated
nitrile of formula CN-(CH2)7-CH=CH2is carried out batchwise, with introduction
of ammonia in a molar excess over the acid and at a temperature of 300°C and
at atmospheric pressure (in the gas phase), in the presence of a zinc oxide
catalyst. The reactor is equipped with a condenser at 100°C. Ammonia is also
injected continuously for 6 hours. The continuous removal of the water formed
entrains the excess ammonia and allows rapid completion of the reaction. 2.6 g
of the nitrile are recovered, and are separated by vacuum distillation.
Example 3 (comparative)
This example illustrates a cross metathesis reaction of a nitrile of formula CN-
(CH2)7-CH=CH2, obtained from the step of example 2, with methyl acrylate,
according to the following reaction:
CH2=CH-(CH2)7-CN + CH2=CH-COOCH3 U
CH300C-CH=CH-(CH2)7-C N + CH2=CH2
A 50 ml Schlenk tube is charged with 83 mg of 9-cyanodecene or 9-
decenenitrile (0.55 mmol), 86 mg of methyl acrylate (1 mmol) and 10 ml of
toluene distilled over sodium-benzophenone. This initial charge is admixed with
1.5 mg (2.4~10m-~m ol) of second-generation Hoveyda-Grubbs catalyst [(I, 3-
bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)dichloro(oisopropoxyphenylmethylene]
ruthenium, sold by the Aidrich0 company). Under
nitrogen and with magnetic stirring, the reaction mixture is heated to 100°C and
left to react for 1 hour. It is analyzed by gas chromatography (dodecane
standard). The conversion is 70%. The selectivity for methyl ester nitrile (cis +
trans mixture) is 100%.
Exam~le4
This example illustrates the variant with reversal of the order of the two steps of
phase I: ammoniation of the unsaturated fatty acid, then ethenolysis of the
unsaturated nitrile.
The ammoniation of oleic acid is carried out batchwise, with introduction of
ammonia in molar excess relative to the acid, and at a temperature of 300°C
and at atmospheric pressure (in the gas phase), in the presence of the zinc
oxide catalyst. The continuous removal of the water formed entrains the excess
ammonia and allows rapid completion of the reaction.
The ethenolysis of the nitrile of oleic acid is carried out at 60°C under
atmospheric pressure in the presence of a ruthenium-based catalyst,
[RuCI2(=CHPh)(lMesH2)(PCy3)u],s ing an excess of ethylene, to give 9-
decenoic acid, CH2=CH-(CH2)7-COOHT. he yields are determined by
chromatographic analysis. At the end of the reaction, 6 hours, the C10 a-olefin
is separated by vacuum distillation, to give the 9-decenoic nitrile CH*=CH-
(CH2),-CN. The yields are determined by chromatographic analysis. It is
possible to measure a yield of 55%.
Example 5
Pyrolysis of hydroxyl-containing fatty acid.
The triglyceride of ricinoleic acid is transesterified by excess methanol in the
presence of sodium methoxide.
The ester is then evaporated at 225°C and subsequently mixed with
superheated steam (620°C). The reaction is short, around ten seconds. The
methyl undecenoate is subsequently purified, first by cooling of the mixture,
which allows the extraction of water, and then by a series of distillations, that
allows the separation of the ester and of the by-products of the reaction.
Example 6: Cross metathesis, butvl acrvlate-10-undecenenitrile
10-Undecenenitrile is purified beforehand over alumina (VWR Normapur basic
alumina). 10 g of alumina are charged to a column, and 20 g of 10-
undecenenitrile are percolated on the column at atmospheric pressure.
The metathesis reactor is a 250 ml double-wall glass reactor equipped with a
magnetic stirrer, a condenser, a temperature probe, a nitrogen inlet, and a
syringe driver for continuous addition of the metathesis catalyst.
After it has been purged with nitrogen, the reactor is charged with 5 g of 10-
undecenenitrile (30 mmol), 7,6 g of butyl acrylate (60 mmol) and 50 g of toluene
dried over molecular sieve. A syringe is charged with 0.5 mg of catalyst of
formula (I) given above (catalyst supplied by the company UMICORE - 7.5~10"
mmol - 0.0025 mol% relative to the 10-undecenenitrile) in solution in 5 ml of
toluene. The reaction mixture is heated to 100°C and then the catalyst is added
via the syringe driver over a period of 3 hours. The resulting reaction mixture is
analyzed by gas chromatography to determine the conversion of 10-
undecenenitrile and the selectivities for unsaturated C12 ester-nitrile (cross
metathesis product) and for unsaturated C20 dintrile (self-metathesis product).
Example 7 (comparative)
Example 7 is carried out under the same conditions as example 6, but using the
catalyst of formula (11) below in the same molar amount.
Formula (11)
Example 8 (comparative)
Example 8 is carried out under the same conditions as example 6, but using the
catalyst of formula (Ill) below in the same molar amount.
Formula (I I I)
Example 9 is carried out under the same conditions as example 6, but replacing
the butyl acrylate by methyl acrylate in the same molar amount.
All of the results from examples 6 to 9 are summarized in table 1 below.
19
Table I
These results show that only the ABuIcatalyst of formula (I) pairing produces
good conversions and selectivities in cross metathesis at low catalyst content.
Example
6
7
8
9
Acrylate
ABu
ABu
ABu
AMe
Catalyst
Formula (I)
Formula (11)
Formula (Ill)
Formula (I)
Conversion
(%I
CI1 nitrile
63
34
21
10
Selectivity (%)
CI2 esternitrile
66
25
26
30
Selectivity
(%I
C2, dinitrile
34
75
74
70

CLAIMS
1) A process for synthesizing an w-amino acid (ester) of formula R300C-
(CH2),-CH2NH2, in which R3 is H or an n-butyl radical and q is an integral index
of between 2 and 13, from a monounsaturated fatty acid (ester) of formula (Rj-
CH=CH-(CH2),-COO),R2, in which x represents 1, 2 or 3, R1 is H or a
hydrocarbon radical comprising from 4 to 11 carbon atoms and, where
appropriate, a hydroxyl function, R2 is H or an alkyl radical comprising from 2 to
4 carbon atoms, and may contain one or more heteroatoms, and p is an integral
index of between 2 and 11, comprising a reaction step of ammoniation, leading
to the conversion of the carbonyl function to a nitrile function, characterized in
that:
- in a first stage, the unsaturated fatty acidlester is converted into an wunsaturated
nitrile of formula CH2=CH-(CH2),-CN in two successive steps, in
any order, ethenolysis and ammoniation, and then
- in a second stage, this w-unsaturated nitrile is converted into an ester nitrile of
formula R300C-CH=CH-(CH2),-CN, in which R3 is n-butyl, by a cross
metathesis reaction of the w-unsaturated nitrile with an acrylate of formula
CH2=CH-COOR3, with a catalyst of formula (I),
and then
- in a third stage, the ester nitrile is hydrogenated to w-amino acid (ester) of
formula ROOC-(CH2),-CH2NH2,
2) The process as claimed in claim 1, characterized in that in the first stage-the
ethenolysis of the acid (ester) is carried out first, followed by the ammoniation of
the w-alkenoic acid.
3) The process as claimed in claim 1, characterized in that in the first stage, the
ammoniation of the acid (ester) is carried out first, followed by the ethenolysis of
the nitrile of the starting fatty acid.
4) The process as claimed in claim 1, characterized in that in the first stage the
pyrolysis of the hydroxyl-containing fatty acid (ester) is carried out first of all,
followed by the ammoniation of the w-alkenoic acid (ester) obtained from the
pyrolysis.
5) The process as claimed in claim 1, characterized in that in the first stage the
ammoniation of the acid (ester) is carried out, without continuing to the
ethenolysis reaction. - .-- - ---- - -. - -
-----_- _
Dated this 3 1" day of January, 20 14
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT[S]