FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
“METHOD FOR OXIDATIVE CLEAVAGE OF OLEFINS USING
A HALOOXODIPEROXOMETALLATE AS A CATALYST”
DEMETA of 6 rue Pierre Joseph Colin 35000 RENNES, France;
UNIVERSITE DE RENNES 1 of 2 rue du Thabor 35000 RENNES,
France;
The following specification particularly describes the invention and the
manner in which it is to be performed.
2
SUBJECT-MATTER OF THE INVENTION
5 The present invention relates to a process for the oxidative cleavage of a substrate consisting of
at least one functionalized or non-functionalized linear olefin, in particular of a mono- or
polyunsaturated aliphatic carboxylic acid, or one of its esters, or of at least one nonfunctionalized cyclic olefin, using hydrogen peroxide, in the presence of a metal catalyst, which
is formed of at least one onium halooxodiperoxometallate. Another subject-matter is a novel
10 catalyst consisting of a specific onium halooxodiperoxometallate which can in particular be
employed in this process.
BACKGROUND OF THE INVENTION
15 Known for many years and always forming the subject of new developments, the oxidative
cleavage of olefins is a chemical reaction which makes possible the conversion of a carboncarbon double bond into two separate oxidized functional groups, such as aldehydes, ketones
or carboxylic acids. This reaction is very particularly advantageous in the upgrading of
vegetable oils. This is because oxidative cleavage converts unsaturated fatty acids in one stage
20 into high-added-value oxidation products, used both in the polymer industry and in the foodprocessing industry or even the perfumery industry. For example, oleic acid is converted by
oxidative cleavage into pelargonic acid and azelaic acid. Azelaic acid, or nonanedioic acid, is a
dicarboxylic acid used as precursor in the manufacture of polymers, such as polyesters or
polyamides, or in the manufacture of lubricants. This compound is also advantageous as
25 cosmetic and dermatological active agent, due to its antimicrobial properties. For its part,
pelargonic acid, or nonanoic acid, is a carboxylic acid which can be used as herbicide, alone or
in combination with azelaic acid, or also as emollient agent.
Ozonolysis, which uses ozone O3 as oxidizing agent, is the most widely employed process for
30 the oxidative cleavage of olefins. Although this process is clean and efficient, the use of ozone
requires the implementation of strict safety measures, as well as the installation of expensive
equipment. The chemical industry has thus turned to the development of catalytic systems based
on transition metals and on oxidizing agents which are less toxic and dangerous. Several
3
processes using catalysts based on precious metals, such as rhenium, ruthenium and gold, have
been developed (WO 2014/020281). However, the high catalytic loads and the absence of
recycling of these expensive catalysts make it difficult to envisage the development of such
processes at the industrial level. In combination with hydrogen peroxide, a relatively
5 inexpensive oxidizing agent, molybdenum and tungsten have also demonstrated their potential
in the oxidative cleavage of olefins.
The patent US 5 336 793 thus describes a process for the preparation of carboxylic acids or
esters by oxidative cleavage of unsaturated esters or acids in a two-phase medium, in which the
10 organic phase contains the reactants and the aqueous phase includes hydrogen peroxide and a
catalyst consisting of tungstic or molybdic acid. The process is characterized by the addition of
an onium salt, such as tetraalkylammonium or tetraalkylphosphonium chloride, which acts as
phase transfer agent, making it possible to bring the catalyst into contact with the reactants and
thus resulting in an improvement in the yield without requiring the use of an organic solvent.
15 The reaction conditions employed in this patent are, however, incompatible with an industrial
application. This is because the reaction products are extracted using ethyl ether in the presence
of aqueous hydrogen peroxide solution and then the solvent is evaporated, potentially resulting
in the formation of diethyl peroxides in the concentrated state and thus of a highly explosive
mixture.
20
The document WO 2013/093366 describes another process for the synthesis of azelaic acid and
pelargonic acid by oxidative cleavage of oleic acid, in which the reaction is carried out in a
single stage, comprising the in situ formation of a catalyst consisting of a quaternary ammonium
salt of phosphotungstic acid, for the purpose of increasing the yield of the reaction. However,
25 the catalytic load by weight used is 19% by weight, which constitutes a value prohibitive for an
industrial process, in view of the high price of phosphotungstic acid.
There thus remains a real need to develop an efficient process for the synthesis of dicarboxylic
acid by oxidative cleavage of olefins, making it possible to obtain this dicarboxylic acid under
30 industrial conditions which are satisfactory from the viewpoint of economics and of the safety
of the process. More generally, the need remains to have available a catalyst which is effective
in the oxidative cleavage of a variety of olefins.
4
In this context, the inventors have developed a process for the oxidative cleavage of olefins
using, as catalyst, an onium salt of a halooxodiperoxometallate. A compound of this type has
already been described in the publication by Ryo Ishimoto et al., Chem. Lett., 2013, 42, 476-
478, where it is used as precursor in the manufacture of a catalyst for the selective oxidation of
5 alkenes. The patent application EP 0 122 804 also mentions a compound obtained by reacting
an onium halide with tungstic acid or a salt, in the presence of hydrogen peroxide at a pH of
less than 2, in particular at a pH of 1, of which it has now been demonstrated that it corresponds
to an onium halooxodiperoxotungstate. In the application EP 0 122 804, this compound is used
as catalyst in the oxidative cleavage of diols, as an alternative to an onium phosphotungstate.
10 However, it is indicated that this alternative provides lower yields of carboxylic acids, unless
p-tert-butylphenol is added to the reaction medium. In point of fact, this compound has recently
been listed as a potential endocrine disruptor by the European Commission. The patent
application JP 2013/144626 also describes the use of mononuclear catalysts, in particular an
onium halooxodiperoxometallate, or binuclear catalysts, in combination with hydrogen
15 peroxide in an olefin epoxidation process. However, very low yields of epoxides are obtained
with the mononuclear catalysts.
It thus remains necessary to provide a process involving less toxic reactants in order to produce
a dicarboxylic acid with good yields.
20
Surprisingly, it has now been demonstrated that this need can be satisfied by using the
alternative catalyst prepared as described in EP 0 122 804 in the oxidative cleavage of olefins.
This is all the more surprising since this oxidative cleavage process involves a cascade of
reactions, comprising the epoxidation of the substrate, and the reaction of the epoxide obtained
25 to form a hydroperoxyalcohol and/or an α-diol, subsequently resulting in the formation of
aldehydes which are finally oxidized to give acids. It was thus not obvious that a single catalyst
may be effective throughout these transformations or in any case not interfere negatively with
one of them.
30
5
SUMMARY OF THE INVENTION
A subject-matter of the invention is thus a process for the oxidative cleavage of a substrate
consisting of at least one functionalized or non-functionalized linear olefin or of at least one
5 non-functionalized cyclic olefin, consisting in converting a carbon-carbon double bond of the
substrate into two separate oxidized functional groups chosen from aldehydes, ketones and
carboxylic acids, using hydrogen peroxide, in the presence of a metal catalyst, characterized in
that the catalyst is formed of at least one onium salt of a halooxodiperoxometallate.
10 Another subject-matter of the invention is novel catalysts of formula (II):
in which:
M is a metal chosen from W and Mo,
15 X is a halogen atom,
L denotes a neutral ligand having at least one non-bonding lone pair,
Q
+
denotes an onium cation of formula N+
(R1R2R3R4), where:
- R1 denotes a linear or branched, preferably linear, C6-C20 alkyl group, R2 and R3 each
independently denote a linear or branched, preferably linear, C1-C4 alkyl group and R4 denotes
20 a linear or branched, preferably linear, C1-C4 alkyl group or an aryl group, or else
- R1 denotes a linear or branched, preferably linear, C4-C14 alkyl group and R2, R3 and
R4 form, with the nitrogen atom, a pyridinium group.
Another subject-matter of the invention is the use of this catalyst in the oxidative cleavage of
25 mono- or polyunsaturated aliphatic carboxylic acids or their esters.
6
DETAILED DESCRIPTION
In one embodiment, the oxidative cleavage process according to the invention uses, as substrate,
at least one functionalized or non-functionalized linear olefin. The term “non-functionalized
5 olefin” is understood to mean a hydrocarbon chain including only carbon and hydrogen atoms
and which comprises at least one unsaturation. The term “functionalized olefin” is understood
to mean a hydrocarbon chain including carbon and hydrogen atoms, comprising at least one
unsaturation, and additionally carrying at least one, and generally from one to four, group(s)
which is (are) inert under the conditions of the oxidative cleavage reaction, in particular chosen
10 from: a carboxyl (-COOH) group, an alkoxycarbonyl (-OCOR) group, a hydroxyl (-OH) group,
a nitro (-NO2) group, a halogen (in particular -Cl or -F) atom, an alkoxy (-OR) group, an
alkylcarbonyl (-COR) group, an amido (-CONH2) or dialkylamino (-NR2) group or a nitrile (-
CN) group, where R denotes a hydrocarbon group including from one to nine carbon atoms.
15 The oxidative cleavage process according to the invention consists in converting a carboncarbon double bond of the substrate into two separate oxidized functional groups, and thus
makes it possible to prepare carbonyl compounds of aldehydes, ketones and/or carboxylic acids
type, and more particularly mono-, di- and/or tricarboxylic acids.
20 In a preferred embodiment of the invention, the olefin is functionalized by at least one carboxyl
or alkoxycarbonyl group. The functionalized linear olefin is thus chosen from mono- or
polyunsaturated aliphatic carboxylic acids and their esters. This carboxylic acid can include
from 6 to 60 carbon atoms, preferably from 6 to 32 carbon atoms, more preferentially from 12
to 24 carbon atoms and more preferentially still from 12 to 18 carbon atoms and it can comprise
25 from 1 to 6 unsaturations, preferably from 1 to 3 unsaturations.
Examples of mono- or polyunsaturated aliphatic carboxylic acid comprise lauroleic acid,
myristoleic acid, palmitoleic acid, sapienic acid, petroselaidic acid, oleic acid, elaidic acid,
petroselinic acid, vaccenic acid, gadoleic acid, cetoleic acid, erucic acid, selacholeic or nervonic
30 acid, α-linoleic acid, γ-linolenic acid, rumenic acid, linolenic acid, stearidonic acid, eleostearic
acid, catalpic acid, arachidonic acid and their mixtures. The acid can optionally be mono- or
polyhydroxylated and chosen in particular from ricinoleic acid. The abovementioned acid can
be obtained by chemical or enzymatic hydrolysis of at least one fatty acid triglyceride typically
resulting from a vegetable oil. Alternatively, it can result from an animal fat. For its part, the
7
ester of the acid can be a triglyceride of the acid or it can be obtained by esterification of the
acid or transesterification of a triglyceride using a monoalcohol. Examples of mono- or
polyunsaturated aliphatic carboxylic acid esters comprise linear or branched C1-C6 alkyl esters,
such as the methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, isopentyl or hexyl esters,
5 without this list being limiting. An example of triglyceride is triolein.
Preferably, oleic acid, palmitoleic acid, erucic acid, linoleic acid, α-linolenic acid, their
mixtures and/or one of their esters, more preferentially oleic acid or one of its esters, in
particular methyl oleate, is/are used.
10
Mention may in particular be made, as examples of vegetable oils, of wheatgerm, sunflower,
argan, hibiscus, coriander, grape seed, sesame, corn, apricot, castor, shea, avocado, olive,
peanut, soybean, sweet almond, palm, rapeseed, cottonseed, hazelnut, macadamia, jojoba,
alfalfa, poppy, red kuri squash, sesame, pumpkin, blackcurrant, evening primrose, lavender,
15 borage, millet, barley, quinoa, rye, safflower, candlenut, passionflower, musk rose, echium,
camelina or camellia oil. Alternatively, one or more oils resulting from biomass of microalgae
can be used.
Examples of mono- and dicarboxylic acids (and their esters) capable of being obtained by
20 oxidative cleavage of the abovementioned acids are collated in the table below.
Unsaturated acids Monoacids Diacids
Oleic Pelargonic Azelaic
Linoleic Hexanoic Azelaic, malonic
Arachidonic Hexanoic Malonic, pentanedioic
Palmitoleic Heptanoic Azelaic
Linolenic Propionic Azelaic, malonic
Ricinoleic 3-Hydroxynonanoic Azelaic
Erucic Pelargonic Brassylic
It is understood that, in the light of the abundance of the unsaturated fatty acids above, the
dicarboxylic acid obtained according to one embodiment of the invention is preferably azelaic
25 acid.
8
In another embodiment of the invention, at least one non-functionalized cyclic olefin is used as
substrate.
5 Examples of non-functionalized cyclic olefins which can be used as substrate in this invention
comprise: cyclohexene, cycloheptene, cyclooctene, cyclononene, cyclodecene, cycloundecene,
cyclododecene, dicyclopentadiene, norbornene and norbornadiene, without this list being
limiting.
10 Examples of dicarboxylic acids (and their esters) capable of being obtained by oxidative
cleavage of non-functionalized cyclic olefins are collated in the table below.
Cyclic olefin Diacids
Cyclohexene Adipic acid
Cycloheptene Pimelic acid
Cyclooctene Suberic acid
Cyclononene Azelaic acid
Cyclodecene Sebacic acid
Cycloundecene Undecanedioic acid
Cyclododecene Dodecanedioic acid
Tricarboxylic acids can be obtained by oxidative cleavage of cyclic olefins exhibiting a
15 constrained cyclic structure, in particular a bridged structure, such as norbornene,
dicyclopentadiene or norbornadiene. For example, the oxidative cleavage of norbornene makes
it possible to obtain butane-1,2,4-tricarboxylic acid.
In the continuation of this description, the term “substrate” will be used for the sake of
20 simplicity to refer both to functionalized or non-functionalized linear olefins and to nonfunctionalized cyclic olefins which can be reacted in the process according to the invention.
In this process, the chosen substrate is oxidized using hydrogen peroxide in the presence of a
specific catalyst.
9
The amount of hydrogen peroxide used in this process is generally between 4 and 20 molar
equivalents, preferably between 4 and 10 molar equivalents and better still between 4 and 8
molar equivalents, limits included, of hydrogen peroxide per one molar equivalent of double
bond present within the substrate. In the case where the substrate consists of a mixture of
5 olefins, in particular of a mixture of functionalized linear olefins, as in the case of vegetable
oils, the number of double bonds can be calculated by referring to the acid numbers and iodine
numbers of these fatty substances, for example according to the Wijs method with iodine
monochloride.
10 Hydrogen peroxide can be used at a concentration of between 1% and 70% (w/V), preferably
between 30% (w/V) and 70% (w/V), limits included, preferably at 60% (w/V).
The catalyst used in the process according to the invention consists of at least one onium
halooxodiperoxometallate. The onium can be chosen from a tetraalkylammonium, a
15 tetraalkylphosphonium and an alkylpyridinium, the alkyl groups of which independently
include from 1 to 20 carbon atoms (preferably from 1 to 18 carbon atoms), benzethonium and
triphenylphosphoranylidene. In the present invention, it is preferred to use a
tetraalkylammonium.
20 Examples of onium ions which can be used according to the invention are in particular:
dodecyltrimethylammonium, trioctylmethylammonium, tetradecyltrimethylammonium,
hexadecyltrimethylammonium, dimethyldihexadecylammonium,
octadecyltrimethylammonium, dioctadecyldimethylammonium,
benzyldimethyldodecylammonium, benzyldimethyltetradecylammonium,
25 benzyldimethylhexadecylammonium, benzyldimethyloctadecylammonium,
dodecylpyridinium, hexadecylpyridinium, benzethonium, tetrabutylammonium,
tetradecyltrihexylphosphonium, hexadecyltributylphosphonium,
bis(triphenylphosphoranylidene)ammonium and tetrabutylammonium.
30 For its part, the halooxodiperoxometallate can be chosen from the compounds of formula (I):
10
where:
M is a metal chosen from W and Mo,
5 X is a halogen atom,
L denotes a neutral ligand having at least one non-bonding lone pair.
Examples of ligands L are water, amines, ethers and phosphines, without this list being limiting.
It is preferred, according to this invention, for L to be H2O.
10
It is furthermore preferred to use halooxodiperoxotungstates (M = W) such as
chlorooxodiperoxotungstate, fluorooxodiperoxotungstate, bromooxodiperoxotungstate and
iodooxodiperoxotungstate, more preferentially chlorooxodiperoxotungstate.
15 The catalyst used according to the invention can be prepared as described by Ryo Ishimoto et
al. in Chem. Lett., 2013, 42, 476-478. Alternatively, it can be synthesized according to a process
comprising:
(a) a first stage in which an aqueous solution of a metal salt, preferably an optionally hydrated
tungstic or molybdic acid salt, in particular an optionally hydrated alkali metal salt, is brought
20 into contact with a strong acid and hydrogen peroxide, in the presence of a molecule L defined
above, and
(b) a second stage consisting in reacting the product resulting from the first stage with an
aqueous solution of an onium halide.
25 The catalyst can subsequently be isolated:
(c1) either by cooling the mixture in order to precipitate the catalyst, which can subsequently
be recovered by filtration and then optionally rinsed with water and/or using an alcohol, such
as ethanol,
11
(c2) or by separation of the organic phase and of the aqueous phase which are obtained,
extraction of the aqueous phase using a water-immiscible solvent, such as dichloromethane,
ethyl acetate, cyclohexane, toluene or methyl tert-butyl ether, in order to obtain a second
organic phase, then drying using a dehydrating agent, such as anhydrous sodium sulfate, and
5 finally evaporation under vacuum of the combined organic phases.
In the first stage above, it is preferred to use sodium tungstate dihydrate as metal salt and
sulfuric acid as strong acid.
10 The amount of strong acid is adjusted so as to bring the pH of the reaction medium to a value
of between 0.5 and 2.0, preferably between 1.0 and 1.5. The hydrogen peroxide is preferably
used in an amount representing from 1 to 10 molar equivalents, more preferentially from 2 to
10 molar equivalents, better still from 3 to 8 molar equivalents, indeed even from 5 to 6 molar
equivalents, with respect to the molar amount of metal acid salt.
15
Examples of onium halides which can be used in the second stage of this process are in
particular: dodecyltrimethylammonium chloride, trioctylmethylammonium chloride,
tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride,
dimethyldihexadecylammonium chloride, octadecyltrimethylammonium chloride,
20 dioctadecyldimethylammonium chloride, benzyldimethyldodecylammonium chloride,
benzyldimethyltetradecylammonium chloride, benzyldimethylhexadecylammonium chloride,
benzyldimethyloctadecylammonium chloride, dodecylpyridinium chloride,
hexadecylpyridinium chloride, benzethonium chloride, tetrabutylammonium chloride,
tetradecyltrihexylphosphonium chloride, hexadecyltributylphosphonium chloride,
25 bis(triphenylphosphoranylidene)ammonium chloride, terabutylammonium fluoride and their
mixtures. Generally, the above chloride salts can be replaced by fluoride, bromide or iodide
salts of the same cations.
In addition, the onium halide added in the second stage is advantageously used in an equimolar
30 amount with respect to the metal acid salt.
The amount of catalyst used in the process according to the invention is generally of between
0.1 molar % and 10 molar %, preferably between 0.5 molar % and 8 molar %, more
12
preferentially between 2 molar % and 6 molar %, with respect to the molar amount of double
bonds present within the substrate. Alternatively or in addition, it can represent from 0.1% to
15% by weight, preferably from 5% to 10% by weight, with respect to the molar amount of
double bonds present within the substrate. The process according to the invention can thus be
5 implemented under economically very advantageous conditions, insofar as it uses a small
amount of catalyst, which can moreover be easily manufactured. In addition, the absence of
toxic metals in this catalyst makes it possible to carry out this process under conditions which
are friendlier to the environment and to human health than some of the processes of the prior
art.
10
As some of the catalysts prepared as described above are novel, another subject-matter of the
invention is these catalysts, of formula (II):
15 in which:
M is a metal chosen from W and Mo,
X is a halogen atom,
L denotes a neutral ligand having at least one non-bonding lone pair,
Q
+
denotes an onium cation of formula N+
(R1R2R3R4), where:
20 - R1 denotes a linear or branched, preferably linear, C6-C20 (for example C12-C18) alkyl
group, R2 and R3 each independently denote a linear or branched, preferably linear, C1-C4 alkyl
group andR4 denotes a linear or branched, preferably linear, C1-C4 alkyl group or an aryl group,
or else
- R1 denotes a linear or branched, preferably linear, C4-C14 alkyl group and R2, R3 and
25 R4 form, with the nitrogen atom, a pyridinium group.
Examples of ligands L are water, amines, ethers and phosphines; preferably, L is H2O.
13
In a specific embodiment, R1 denotes a linear or branched, preferably linear, C12-C18 (for
example C12-C14) alkyl group, R2 and R3 each independently denote a linear or branched,
preferably linear, C1-C4 alkyl group and R4 denotes a linear or branched, preferably linear, C1-
C4 alkyl group or an aryl group.
5
In another specific embodiment, R1 denotes a linear or branched, preferably linear, C6-C20 (for
example C12-C14) alkyl group, R2 and R3 each denote a methyl group and R4 denotes a methyl
group or an aryl group.
10 In a preferred embodiment of the invention, R1 denotes a linear or branched, preferably linear,
C12-C18 (for example C12-C14) alkyl group, R2 and R3 each denote a methyl group andR4 denotes
a methyl group or an aryl group.
In the case where the linear olefin is a mono- or polyunsaturated aliphatic carboxylic acid, or
15 one of its esters, the novel catalysts above make it possible to obtain the desired dicarboxylic
acid with a molar yield of at least 40%, preferably of at least 50%, at least 60%, at least 70%,
indeed even at least 80% or even at least 90%.
Furthermore, the halogen is preferably chlorine or fluorine, more preferentially chlorine.
20 Examples of catalysts corresponding to the above definition are given above. Among these,
dodecyltrimethylammonium chlorooxodiperoxotungstate is preferred for its ease of preparation
without organic solvent and its efficiency.
The oxidative cleavage process according to the invention generally comprises the stages
25 consisting in:
- mixing the catalyst, previously formed in situ or isolated, with the substrate, optionally
brought beforehand to a temperature of 20 to 120°C, and with hydrogen peroxide, preferably at
ambient temperature,
- bringing the mixture to a temperature of from 20 to 120°C, preferably from 50 to 120°C, more
30 preferentially from 50 to 100°C, or better still from 80 to 100°C, with stirring, for example at
50-1200 revolutions/min, for a period of time which can, for example, range from 2 to 24 hours,
in particular from 4 to 6 hours, and
14
- recovering the products thus formed by any means, in particular by crystallization, filtration,
distillation, liquid-liquid extraction or chromatographic purification.
In a specific embodiment, the substrate consists of at least one monounsaturated linear olefin,
5 and is employed in the preparation of at least one monocarboxylic acid. In such a specific
embodiment, the olefin is non-functionalized, or else functionalized by any group other than a
carboxyl.
In another specific embodiment of the invention, the substrate consists of at least one cyclic
10 olefin (such as cyclohexene, cycloheptene, cyclooctene, cyclononene, cyclodecene,
cycloundecene, cyclododecene, dicyclopentadiene, norbornene and norbornadiene, without this
list being limiting), and is employed in the preparation of at least one di- or tricarboxylic acid
or one of its esters.
15 In a preferred embodiment of the invention, the substrate consists of at least one mono- or
polyunsaturated aliphatic carboxylic acid or one of its esters, and is employed in the preparation
of at least one dicarboxylic acid or one of its esters, and optionally of at least one
monocarboxylic acid.
20 In this preferred embodiment, the oxidative cleavage process according to the invention
generally comprises the stages consisting in:
- mixing the catalyst, previously formed in situ or isolated, with the substrate, optionally
brought beforehand to a temperature of 20 to 120°C, and with hydrogen peroxide, preferably at
ambient temperature,
25 - bringing the mixture to a temperature of from 20 to 120°C, preferably from 50 to 120°C, more
preferentially from 50 to 100°C, or better still from 80 to 100°C, with stirring, for example at
50-1200 revolutions/min, for a period of time which can, for example, range from 2 to 24 hours,
in particular from 4 to 6 hours, and
- recovering the dicarboxylic acid or its ester thus formed, and optionally the monocarboxylic
30 acid or its ester obtained as coproduct.
Advantageously, this process does not use an organic solvent, in particular chosen from 1,2-
dichloroethane, dichloromethane, chloroform, ethyl ether, tert-butanol or acetonitrile.
15
The dicarboxylic acid can be recovered by crystallization, followed by filtration or
centrifugation. To do this, the reaction mixture can be cooled, for example to 0-30°C and
preferably to 15-25°C, in order to precipitate the dicarboxylic acid. The latter can subsequently
be optionally redissolved in water and then precipitated from an appropriate solvent, in
5 particular a non-polar organic solvent, such as heptane, which makes it possible to extract the
monocarboxylic acid formed simultaneously.
Examples of dicarboxylic acids which can be prepared according to this preferred embodiment
of the invention are in particular azelaic acid, adipic acid, succinic acid, sebacic acid, 1,7-
10 heptanedioic acid, 1,8-octanedioic acid, 1,11-undecanedioic acid, 1,12-dodecanedioic acid,
brassylic acid, 1,14-tetradecanedioic acid, 1,15-pentadecanedioic acid and thapsic acid,
preferably azelaic acid, adipic acid, succinic acid, sebacic acid, 1,12-dodecanedioic acid,
brassylic acid and thapsic acid, better still azelaic acid.
15 These dicarboxylic acids can be used in particular as monomer in the manufacture of polymers,
such as polyesters or polyamides, as plasticizer, in the manufacture of esters or of lubricants or
as cosmetic or dermatological active agent. When the dicarboxylic acid consists of azelaic acid,
it can additionally be used as antibacterial active agent intended in particular for the treatment
of acne or rosacea.
20
The mono-, di- or tricarboxylic acids prepared by the process of the invention can subsequently
be reduced to give alcohols, for example by means of lithium aluminum hydride, as described
in Biomacromolecules, 2010, 11, 911–918 (reduction of azelaic acid to give 1,9-nonanediol),
or by metallo-catalyzed hydrogenation (Chem. Commun., 2018, 54, 13319).
25
FIGURES
[Fig 1] represents the molecular structure of the compound described in example 2, obtained
by XRD and represented with 50% probability ellipsoids.
30
EXAMPLES
16
A better understanding of the invention will be obtained in the light of the following examples,
which are given purely by way of illustration and do not have the aim of limiting the scope of
the invention, defined by the appended claims.
5 Materials and methods
The reactants originate from ordinary commercial suppliers (Sigma-Aldrich-Merck, Acros,
Alfa-Aesar, Fisher) and were used without prior purification.
All the reactions were carried out in air, at atmospheric pressure.
The GC-MS analyses were carried out with a Shimadzu QP2010SE instrument, using H2 as
10 carrier gas, with a Zebron Fast GC (Phenomenex) (20 m x 0.18 mm x 0.18 μm) column. The
GC-MS quantification was carried out using octanoic acid as internal standard. The
concentrations of azelaic acid, pelargonic acid and oleic acid were calculated using a calibration
curve (R
2 > 0.99 in the three cases).
The proton Nuclear Magnetic Resonance (NMR) spectra were recorded on an Avance 400
15 NMR spectrometer at 400.1 MHz (Bruker) at 25°C. The chemical shifts are expressed in ppm
(parts per million) with respect to the signal of the residual non-deuterated solvent. The
multiplicity of the signals is described as follows: singlet (s), doublet (d), triplet (t) and multiplet
(m).
20 Example 1: General process for the preparation and characterization of the catalysts
1A) Preparation by precipitation (case of the water-insoluble ammoniums, such as
dodecyltrimethylammonium chloride and hexadecylpyridinium chloride):
25 Na2WO4.2H2O (6.93 mmol, 1.00 eq.) is introduced into a 50 ml round-bottomed flask and then
5 ml of distilled water are added in order to dissolve Na2WO4.2H2O. An H2SO4 solution (2M,
5 mmol; 0.72 eq.) is subsequently added to this solution, immediately followed by the addition
of aqueous hydrogen peroxide solution (30 w/v %; 37.48 mmol; 5.4 eq.). The solution turns
yellow and then virtually colorless. The pH of the latter is located between 0.9 and 1.1; if not,
30 it can be adjusted with a few additional drops of the H2SO4 solution. The alkylammonium
chloride, dissolved beforehand in 5 ml of distilled water, is subsequently added dropwise (7.28
mmol; 1.05 eq.). The medium is subsequently stirred at 20°C for 30 minutes, then placed under
cold conditions (4°C) overnight. The precipitate formed is filtered off and then rinsed with H2O
17
(4 x 50 ml) and then with ethanol cooled to 0°C (25 ml). The product is subsequently predried
on a rotary evaporator and then dried overnight under vacuum in the presence of P2O5.
1B) Preparation by extraction (case of all the other ammoniums and phosphoniums, also
5 applicable to those prepared by precipitation):
Na2WO4.2H2O (6.93 mmol; 1.0 eq.) is introduced into a 50 ml round-bottomed flask and then
5 ml of distilled water are added in order to dissolve Na2WO4.2H2O. An H2SO4 solution (2M,
5 mmol; 0.72 eq.) is subsequently added to this solution, immediately followed by the addition
10 of aqueous hydrogen peroxide solution (30 w/v %; 37.48 mmol; 5.4 eq.). The solution turns
yellow and then virtually colorless. The pH of the latter is located between 0.9 and 1.1; if not,
it can be adjusted with a few additional drops of the H2SO4 solution. The alkylammonium
halide, in solution in 10 ml of dichloromethane, is subsequently added to the medium (7.28
mmol; 1.05 eq.). The solution is subsequently stirred vigorously at 20°C for 1 h 30. The phases
15 are subsequently separated and the aqueous phase is extracted with 15 ml of dichloromethane.
The organic phase is dried with anhydrous sodium sulfate and then evaporated on a rotary
evaporator. The solid obtained is dried under vacuum overnight.
The yields obtained on conclusion of the above processes are collated in the following table.
20
Halooxodiperoxometallate catalyst Isolated yield
Dodecyltrimethylammonium chlorooxodiperoxotungstate 85%
Trioctylmethylammonium chlorooxodiperoxotungstate 66%
Tetradecyltrimethylammonium chlorooxodiperoxotungstate 34%
Octadecyltrimethylammonium chlorooxodiperoxotungstate 86%
Dimethyldioctadecylammonium chlorooxodiperoxotungstate 47%
Tetrabutylammonium chlorooxodiperoxotungstate 62%
Benzyldimethyldodecylammonium chlorooxodiperoxotungstate 36%
Benzyldimethyltetradecylammonium chlorooxodiperoxotungstate 60%
Benzyldimethylhexadecylammonium chlorooxodiperoxotungstate 52%
Benzyldimethylstearylammonium chlorooxodiperoxotungstate 79%
Dodecylpyridinium chlorooxodiperoxotungstate 58%
18
Hexadecylpyridinium chlorooxodiperoxotungstate 75%
Benzethonium chlorooxodiperoxotungstate 58%
Tetradecyltrihexylphosphonium chlorooxodiperoxotungstate 62%
Bis(triphenylphosphoranylidene)ammonium
chlorooxodiperoxotungstate
68%
Tetrabutylammonium fluorooxodiperoxotungstate
Example 2: Preparation and characterization of dodecyltrimethylammonium
chlorooxodiperoxotungstate
5
Na2WO4.2H2O (6.93 mmol, 1.00 eq.) is introduced into a 50 ml round-bottomed flask and then
5 ml of distilled water are added in order to dissolve Na2WO4.2H2O. An H2SO4 solution (2M,
5 mmol; 0.72 eq.) is subsequently added to this solution, immediately followed by the addition
of aqueous hydrogen peroxide solution (30 w/v %; 37.48 mmol; 5.4 eq.). The solution turns
10 yellow and then virtually colorless. The pH of the latter is located between 0.9 and 1.1; if not,
it can be adjusted with a few additional drops of the H2SO4 solution.
Dodecyltrimethylammonium chloride, dissolved beforehand in 5 ml of distilled water, is
subsequently added dropwise (7.28 mmol; 1.05 eq.). A white precipitate forms, then
redissolves. The medium is subsequently stirred at 20°C for 30 minutes, then placed under cold
15 conditions (4°C) overnight. The precipitate formed is filtered off and then rinsed with H2O (4
x 50 ml) and then with ethanol cooled to 0°C (25 ml). The product is subsequently predried on
a rotary evaporator and then dried overnight under vacuum in the presence of P2O5.
Dodecyltrimethylammonium chlorooxodiperoxotungstate is obtained in the form of a white
powder with a molar yield of 85%.
20
1H NMR (CDCl3, 400 MHz) δ: 0.75 (m, 3H); 1.06-1.30 (m, 18H); 1.60 (m, 2H); 3.06-3.20 (s,
9H); 3.81 (m, 2H); 13C NMR (101 MHz, CDCl3) δ: 66.8, 52.9, 31.8, 29.5, 29.4, 29.2, 26.2, 23.0,
22.5, 13.9; IR νmax 2915, 2850, 1469, 947, 835, 775, 720, 619, 572, 547, 486, 419.
25 Single-crystal X-ray diffraction:
19
The measurements were carried out on a D8 VENTURE Bruker AXS diffractometer equipped
with a PHOTON 100 (CMOS) detector, with Mo-Kα radiation (λ = 0.71073 Å, multilayer
monochromator), T = 150(2) K; monoclinic crystal P 21/c (I.T. # 14), a = 18.8525(16), b =
7.3078(7), c = 15.3995(14) Å, β = 97.340(4)°, V = 2104.2(3) Å3
. Z = 4, d = 1.723 g.cm-3
, μ =
5.643 mm-1
5 . The structure was solved by a dual space algorithm using the SHELXT program
[G.M. Sheldrick, Acta Cryst., A71 (2015), 3-8], then refined by full matrix least squares
methods based on F2 (SHELXL) [Sheldrick G.M., Acta Cryst., C71 (2015), 3-8]. All the atoms
other than hydrogen were refined with anisotropic atomic shift parameters. A final refinement
on F2 with 4810 unique intensities and 227 parameters converged to ωR(F2) = 0.0496 (R(F) =
10 0.0218) for 4125 reflections observed with I > 2σ(I).
The structure obtained is illustrated in the appended figure.
15 Example 3: Oxidative cleavage of oleic acid
A 250 ml single-necked round-bottomed flask equipped with a 20 x 10 mm magnetic bar is
charged with dodecyltrimethylammonium chloroperoxotungstate catalyst (700 mg, 1.28 mmol,
0.040 eq.) and then with oleic acid (90% purity) (10.0 g, 31.86 mmol, 1.0 eq.). The mixture is
20 stirred at 300 revolutions/min at 22°C for 5 min, forming a homogeneous white liquid phase.
60% (w/V) aqueous hydrogen peroxide solution (10.84 ml, 191.16 mmol, 6.0 eq.) is then added
dropwise to this mixture at 22°C with stirring over 5 min. The round-bottomed flask is
subsequently equipped with a reflux condenser and the reaction mixture is brought to reflux by
contact with a metal heating block (DrySyn block, Asynt) preheated to 90°C, with stirring at
25 1000 revolutions/min, for 5 h. During the reaction, the reaction medium remains two-phase,
with a white lower phase and a colorless upper phase. On completion of the reaction, the
medium is allowed to cool to 22°C. After cooling, a white solid appears at the bottom of the
round-bottomed flask.
A GC-MS analysis of the medium is carried out after derivatization with trimethylsulfonium
30 hydroxide (0.2 mol/l in methanol), according to a procedure described in Journal of
Chromatography A, 2004, 1047, 111–116. The molar yields are then calculated with the help
of a calibration curve, using octanoic acid as internal standard: azelaic acid 98%, pelargonic
acid 74%.
20
The azelaic acid can be isolated by virtue of the following procedure: on completion of the
reaction, 25 ml of deionized water are added to the round-bottomed reaction flask and then the
mixture is heated to 90°C, with stirring at 300 revolutions/min. After heating for 10 min, the
white solid dissolves completely, thus giving an offwhite solution. 20 ml of heptane are then
5 added to the mixture and stirring is continued at 90°C for 10 min. The heating and the stirring
are subsequently stopped and the medium is then allowed to cool to 22°C. After 3 h, a white
solid appears at the bottom of the round-bottomed flask, the upper phase being colorless. This
mixture is then filtered on a Whatman glass microfiber disc (4.25 cm in diameter, reference
1820042) and rinsed with 3 x 75 ml of heptane. The white solid, consisting of azelaic acid, is
10 collected and dried under reduced pressure in a desiccator, in the presence of P2O5. A weight
of 6.44 g is obtained. The filtrate can be evaporated under reduced pressure, to give pelargonic
acid in the form of a colorless oil.
The purity of the azelaic acid obtained is calculated by GC-MS analysis after derivatization
with N,O-bis(trimethylsilyl)trifluoroacetamide with 1% of trimethylchlorosilane: 50 mg of
15 azelaic acid are dissolved in 1 ml of THF, then 10 μl of this solution are introduced into a GC
vial, followed by the addition of 100 μl of anhydrous pyridine and then 100 μl of N,Obis(trimethylsilyl)trifluoroacetamide with 1% of trimethylchlorosilane. The mixture is heated
and stirred in the GC vial at 40°C for 1 h, then diluted with 600 μl of THF and injected in GCMS. After GC-MS analysis, a purity of 91% is determined for the azelaic acid, the remainder
20 consisting of traces of pelargonic acid (7%) and of C4 impurities (2%).
Taking into account the calculated purities and the weight of azelaic acid collected, the
corrected isolated molar yield of azelaic acid is 97%.
25 By following the same protocol as in example 2 but with the other catalysts, the following
yields are obtained:
Catalyst Azelaic
acid yield
(%)
Pelargonic
acid yield
(%)
[WO(O2)2Cl.H2O][tetradecyltrimethylammonium] 78% 72%
[WO(O2)2Cl.H2O][octadecyltrimethylammonium] 69% 67%
21
[WO(O2)2Cl.H2O][trioctylmethylammonium] 39% 38%
[WO(O2)2Cl.H2O][dimethyldioctadecylammonium] 39% 38%
[WO(O2)2Cl.H2O][benzyldimethyldodecylammonium] 71% 68%
[WO(O2)2Cl.H2O][benzyldimethyltetradecylammonium] 68% 68%
[WO(O2)2Cl.H2O][benzyldimethylhexadecylammonium] 71% 66%
[WO(O2)2Cl.H2O][benzyldimethylstearylammonium] 68% 69%
[WO(O2)2Cl.H2O][dodecylpyridinium] 62% 59%
[WO(O2)2Cl.H2O][hexadecylpyridinium] 70% 66%
[WO(O2)2Cl.H2O][benzethonium] 64% 62%
[WO(O2)2Cl.H2O][tetradecyltrihexylphosphonium] 39% 40%
[WO(O2)2Cl.H2O][bis(triphenylphosphoranylidene)ammonium] 55% 54%
[WO(O2)2Cl.H2O][tetrabutylammonium] 64% 59%
[WO(O2)2F.H2O][tetrabutylammonium] 40% 38%
[MoO(O2)2Cl.H2O][dodecyltrimethylammonium] 40% 37%
Example 4: Oxidative cleavage of cyclohexene
A reactor (external diameter 16 mm, 15 ml) equipped with a 10 x 5 mm magnetic bar is charged
5 with dodecyltrimethylammonium chlorooxodiperoxotungstate catalyst (44.7 mg; 0.08 mmol;
22
0.029 eq.) and then with cyclohexene (99% purity) (234.9 mg; 2.83 mmol; 1.0 eq.). 60% (w/V)
aqueous hydrogen peroxide solution (960 μl; 16.93 mmol; 5.9 eq.) is then added to this mixture.
The reaction mixture is heated by contact with a metal heating block (DrySyn block, Asynt)
already preheated to 90°C, with stirring at 1000 revolutions/min, for 5 h. During the reaction,
5 the reaction medium becomes monophasic and completely clear. On completion of the reaction,
the medium is allowed to cool to 25°C, letting a white solid appear at the bottom of the reactor.
Analysis of the reaction and quantification by 1H NMR: an internal standard, 1,4-
dibromobenzene (669.5 mg; 2.83 mmol), is then added to a 25 ml volumetric flask and then the
entire reaction medium is homogenized with d6-DMSO before being added to the volumetric
10 flask. The latter is then made up to volume with deuterated dichloromethane until the internal
standard has completely dissolved and then with d6-DMSO up to the graduation mark. 1H NMR
analysis of this mixture is carried out and makes it possible to calculate a 90% molar yield of
adipic acid.

Claims
1. A process for the oxidative cleavage of a substrate consisting of at least one functionalized
or non-functionalized linear olefin or of at least one non-functionalized cyclic olefin, consisting
5 in converting a carbon-carbon double bond of the substrate into two separate oxidized
functional groups chosen from aldehydes, ketones and carboxylic acids, using hydrogen
peroxide, in the presence of a metal catalyst, characterized in that the catalyst is formed of at
least one onium halooxodiperoxometallate.
10 2. The process as claimed in claim 1, characterized in that the onium is chosen from a
tetraalkylammonium, a tetraalkylphosphonium and an alkylpyridinium, the alkyl groups of
which independently include from 1 to 20 carbon atoms, benzethonium and
triphenylphosphoranylidene, preferably a tetraalkylammonium.
15 3. The process as claimed in claim 1 or 2, characterized in that the halooxodiperoxometallate is
chosen from the compounds of formula (I):
where:
20 M is a metal chosen from W and Mo,
X is a halogen atom,
L denotes a neutral ligand having at least one non-bonding lone pair.
4. The process as claimed in claim 3, characterized in that L is chosen from water, amines,
25 ethers and phosphines; preferably, L is H2O.
5. The process as claimed in claim 3 or 4, characterized in that the halooxodiperoxometallate is
chosen from chlorooxodiperoxotungstate, fluorooxodiperoxotungstate,
24
bromooxodiperoxotungstate and iodooxodiperoxotungstate, preferably
chlorooxodiperoxotungstate.
6. The process as claimed in any one of claims 1 to 5, characterized in that the catalyst is
5 employed in an amount ranging from 0.1 molar % to 10 molar %, preferably between 0.5 molar
% and 8 molar %, more preferentially from 2 molar % to 6 molar %, with respect to the molar
amount of double bonds in the substrate.
7. The process as claimed in any one of claims 1 to 6, characterized in that the hydrogen
10 peroxide is employed in an amount ranging from 4 to 20 molar equivalents, preferably from 4
to 8 molar equivalents, with respect to the molar amount of double bonds in the substrate.
8. The process as claimed in any one of claims 1 to 7, characterized in that the substrate consists
of at least one mono- or polyunsaturated aliphatic carboxylic acid or one of its esters, and in
15 that it is employed in the preparation of at least one dicarboxylic acid or one of its esters,
respectively, and optionally of at least one monocarboxylic acid.
9. The process as claimed in claim 8, characterized in that the mono- or polyunsaturated
aliphatic carboxylic acid or one of its esters is chosen from: oleic acid, palmitoleic acid, erucic
20 acid, linoleic acid, α-linolenic acid, their mixtures and/or one of their esters, more preferentially
oleic acid or one of its esters, in particular methyl oleate.
10. The process as claimed in any one of claims 8 and 9, characterized in that the dicarboxylic
acid is chosen from azelaic acid, adipic acid, succinic acid, sebacic acid, 1,7-heptanedioic acid,
25 1,8-octanedioic acid, 1,11-undecanedioic acid, 1,12-dodecanedioic acid, brassylic acid, 1,14-
tetradecanedioic acid, 1,15-pentadecanedioic acid and thapsic acid, preferably azelaic acid,
adipic acid, succinic acid, sebacic acid, 1,12-dodecanedioic acid, brassylic acid and thapsic
acid, better still azelaic acid.
30 11. The process as claimed in any one of claims 8 to 10, characterized in that it comprises the
stages consisting in:
- mixing the catalyst, previously formed in situ or isolated, with the substrate, optionally
brought beforehand to a temperature of 20 to 120°C, and with hydrogen peroxide,
25
- bringing the mixture to a temperature of from 20 to 120°C, preferably from 50 to 120°C, more
preferentially from 50 to 100°C, or better still from 80 to 100°C, for a period of time which can,
for example, range from 2 to 24 hours, in particular from 4 to 6 hours, with stirring, and
- recovering the dicarboxylic acid or its ester thus formed, and optionally the monocarboxylic
5 acid or its ester obtained as coproduct.
12. The process as claimed in any one of claims 1 to 7, characterized in that the substrate
consists of at least one non-functionalized cyclic olefin, preferably chosen from: cyclohexene,
cycloheptene, cyclooctene, cyclononene, cyclodecene, cycloundecene, cyclododecene,
10 dicyclopentadiene, norbornene and norbornadiene.
13. A catalyst of formula (II):
15 in which:
M is a metal chosen from W and Mo,
X is a halogen atom,
L denotes a neutral ligand having at least one non-bonding lone pair; preferably, L is H2O.
Q
+
denotes an onium cation of formula N+
(R1R2R3R4), where:
20 - R1 denotes a linear or branched, preferably linear, C6-C20 alkyl group, R2 and R3 each
independently denote a linear or branched, preferably linear, C1-C4 alkyl group and R4 denotes
a linear or branched, preferably linear, C1-C4 alkyl group or an aryl group, or else
- R1 denotes a linear or branched, preferably linear, C4-C14 alkyl group and R2, R3 and
R4 form, with the nitrogen atom, a pyridinium group.
25
14. The catalyst as claimed in claim 13, characterized in that R1 denotes a linear or branched,
preferably linear, C12-C18 alkyl group, R2 and R3 each denote a methyl group and R4 denotes a
methyl group or an aryl group.
26
15. The catalyst as claimed in claim 13 or 14, characterized in that the halogen is chlorine or
fluorine, preferably chlorine.
16. The catalyst as claimed in any one of claims 13 to 15, characterized in that it consists of
5 dodecyltrimethylammonium chlorooxodiperoxotungstate.
17. The use of the catalyst as claimed in any one of claims 13 to 16 in the oxidative cleavage
of mono- or polyunsaturated aliphatic carboxylic acids or their esters.