Note: Descriptions are shown in the official language in which they were submitted.
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
1
A METHOD OF PURIFYING A DICARBOXYLIC ACID COMPOUND
FIELD OF THE INVENTION
[0001] The present invention relates to a method of purifying a
dicarboxylic acid
compound obtained from the oxidative ozonolysis of ethylenically unsaturated
compounds,
and an apparatus for carrying out the method.
BACKGROUND OF THE INVENTION
[0002] Commercial production of azelaic acid and pelargonic acid has been
realized
via an oxidative cleavage of an alkenyl (-C=C-) unit in oleic acid. For
example, azelaic acid
has been prepared from oleic acid by oxidation with chromium sulfate, as
disclosed in U.S.
Patent No. 2,450,858. However, because stoichiometric use of chromium reagents
is
undesirable, a more efficient approach utilizing ozone has been developed, as
disclosed and
described in U.S. Patent Nos. 2,813,113; 5,801,275; 5,883,269; and 5,973,173.
[0003] The basic process will be best understood by referring to the
description in the
accompanying FIG. 1, which is a diagrammatic flow chart indicating the pieces
of equipment
used and their relationship in the ozonolysis process. Referring to FIG. 1,
oleic acid is
supplied to a feed tank 10 and then to an ozone absorber 13, wherein the oleic
acid is flowed
counter-current to a continuous flow of an oxygen/ozone gas mixture introduced
to the ozone
absorber 13. The ozone absorber 13 is cooled or refrigerated to substantially
control the
temperature of the reaction occurring therein.
[0004] The ozone absorber 13 receives ozonized oxygen gas by a continuous
closed
system through which the oxygen circulates. Thus, a given portion of oxygen is
used and
reused multiple times and the system need be bled and fed only to a small
extent to maintain
the oxygen content at a predetermined high level. The circulating oxygen
system comprises
an oxygen supply 16 that leads to a dehydrator 19. From the dehydrator 19, the
oxygen is
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
2
transferred to an ozone generator 22, which converts a quantity of the oxygen
to ozone by
using electricity. From the ozone generator 22, a gaseous mixture of ozone and
oxygen
passes into the ozone absorber 13 in which substantially all of its ozone
content is absorbed
by the oleic acid to form an oleic acid ozonide. During the residence time of
the oleic acid
ozonide mixture in the ozone absorber 13, the mixture may increase in
viscosity. If desired,
the viscosity of the mixture may be reduced by introducing compatible
solvents, as discussed
further below.
[0005] Upon exiting the ozone absorber 13, the gas mixture, now
substantially devoid
of ozone, passes to an electrostatic precipitator 25, which removes any fine
mist organic
matter that may have been picked up in the ozone absorber 13. The purified gas
mixture then
passes from the electrostatic precipitator 25 through a compression pump 28 to
a cooler 31
and then returns to the dehydrator 19, in which substantially all moisture is
removed from the
gas mixture. Between the cooler 31 and the dehydrator 19, oxygen-containing
gas, which
may be obtained from or bled from the system through an ozone generating
system valve 34,
may be supplied to the ozonide decomposing system reactor 37.
[0006] The aforementioned absorption of ozone by oleic acid forms oleic
acid
ozonides, which are transferred to the ozonide decomposing system reactor 37
and treated
with oxygen bled from the ozone generating system valve 34. The ozonide
decomposing
system reactor 37 may be any type device which is adapted to provide
substantial interfacial
contact between a liquid and a gas and which may be cooled to moderate the
temperature of
the reaction. The oxygen bled from the ozone generating system is fed into the
bottom of the
ozonide decomposing system reactor 37 and is agitated with the liquid in each
tank by means
of mechanical agitators which are not shown.
[0007] While only one integral ozonide decomposing system reactor 37 is
shown in
the drawing, it is to be understood that the reactor 37 may comprise distinct
regions
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
3
configured for independent temperature, independent pressure control, or both.
Alternatively,
any number of reactors may be used depending upon the size of the reactors,
the rate of the
flow of the ozonides and their decomposition products, and the efficiency of
the agitation in
effecting contact between the oxygen gas and the liquid being treated.
Further, alternative
embodiments having more than one reactor may be connected in series
configuration, parallel
configuration, or both.
[0008] Temperature control is an important operating parameter for the
ozonide
decomposing system reactor 37. More specifically, the incoming stream of
ozonides must be
heated to reach a suitable reaction temperature at which the ozonide moiety
may efficiently
undergo oxidative decomposition upon exposure to one or more catalysts to
preferentially
form an aldehyde and a carboxylic acid. The ozonide decomposition catalysts
may include
BrOnsted¨Lowry acids, Bronsted¨Lowry bases, Lewis acids, Lewis bases, metals,
or salts
and soaps thereof. Exemplary ozonide decomposition catalysts may include at
least in part,
Na, K, B, Sn, Zn, Pt, Pd, Rh, Ag, Mn, Cu, Ni, titania/silica or titania/P205
composites, and
combinations thereof. The catalyst can be introduced into the process in the
form of a
soluble material or in the form of a solid or supported catalyst.
[0009] After reaching a suitable reaction temperature, further oxidation
of the
aldehyde functional group to a carboxylic acid functional group may occur at a
rate sufficient
to generate heat, which may in turn contribute to elevating the temperature of
the incoming
stream of ozonides. However, cooling water may need to be supplied in order to
prevent the
temperature from rising above a predetermined level. As such, the temperature
is controlled
in order to be suitable for efficient oxidation to convert the ozonides to
mixed oxidation
products. In FIG. 1, the heating and cooling apparatus are not shown.
[0010] From the ozonide decomposing system reactor 37, the mixed oxidation
products pass to a first distillation unit 40 wherein pelargonic acid and
other carboxylic acids
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
4
are distilled from the mixed oxidation products to form a first distillate and
a first residue of
the mixed oxidation products. The first distillate, which contains pelargonic
acid, is
converted to a liquid in a first condenser 43 and then is delivered to a crude
pelargonic acid
storage tank 46. However, some of the crude pelargonic acid may be used to
dilute the oleic
acid reactant and the oleic acid ozonides in the absorber 13 if desired. Thus,
pelargonic acid,
which may be crude or further purified, may be added to the ozone absorber 13
in order to
reduce the viscosity of the ozonides in the absorber 13. The amount of
recycled pelargonic
acid supplied to the absorber 13 may be controlled with a valve 49.
[0011] It should be noted that other viscosity reducers and diluents may be
used. The
diluents can be known materials which do not readily react with ozone and
which are
compatible with the ozonides or the reaction products, or can be a portion of
the reaction
product. Such diluents include, but are not limited to, saturated short chain
acids such as
acetic acid, butanoic acid, caproic acid, heptanoic acid, caprylic acid,
pelargonic acid, and
capric acid; esters such as ethyl acetate and butyl acetate; and alkanes such
as hexane, octane,
and decane. However, the use of pelargonic acid is recommended because, as an
end product
of the process, it does not interfere with the operation of the circulating
oxygen system and
requires no separate distillation. In other words, since pelargonic acid is
one of the end
products of the process, it is a suitable diluent.
[0012] The first residue of the mixed oxidation products, now stripped of a
substantial
portion of the available pelargonic acid, are next conveyed to an azelaic acid
distillation unit
52 in which a portion of the first residue of the mixed oxidation products is
distilled to form a
second distillate, which includes azelaic acid, and a second residue of the
mixed oxidation
products. The second distillate is condensed by passage through an azelaic
acid distillate
condenser 55 to form a crude azelaic acid, which is transferred to a crude
azelaic acid storage
tank 58. The second residue of the mixed oxidation products or pitch that
remains after
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
distilling away the second distillate is removed from the azelaic acid
distillation unit 52 and
transferred to residue storage 61. The second residue of the mixed oxidation
products may
still contain some amount of azelaic acid, so further processing, if desired,
can occur to
recover a portion thereof.
[0013] From the crude azelaic acid storage tank 58, the crude azelaic acid
is
transferred to extractor 64 where the crude azelaic acid is extracted with hot
water (e.g., about
175 F, about 80 C to about 210 F, about 99 C) to form a hot aqueous solution
of azelaic
acid. The by-product acids (BPA) that do not dissolve in the hot aqueous
azelaic acid
solution are decanted from the extractor 64 to BPA storage 67. Meanwhile, the
hot aqueous
azelaic acid solution is transferred to an evaporator 70 in which water is
removed therefrom.
Next, azelaic acid in molten form is fed from the evaporator 70 to a Baker 73
where the
temperature is reduced to below the melting point, and then solid flakes of
azelaic acid are
conveyed to an azelaic acid storage bin 76.
[0014] While the process and apparatus described above provide desirable
products
such as azelaic and pelargonic acids from oleic acid, deficiencies exist with
respect to
chemical purity of the product(s), personnel safety, system efficiencies and
equipment
longevity. One such deficiency of the prior art procedure and apparatus
pertains to achieving
high purity of the azelaic acid, without sacrificing its overall yield. For
example, certain
impurities in the crude azelaic acid, such as long chain (e.g. C14 to C18)
monocarboxylic
acids, are difficult to remove by distillation insofar as the boiling points
can be very similar.
Depending on the application for the azelaic acid, a monocarboxylic acid
impurity may be
problematic. For example, monocarboxylic acids can act as a "chain stopper"
during the
formation of long linear polymers (e.g. polyamides) from the dicarboxylic
acid. As such,
new procedures are needed to purify dicarboxylic acids such as azelaic acid.
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
6
SUMMARY OF THE INVENTION
[0015] According to embodiments of the present invention, a process for
purifying a
dicarboxylic acid is provided. The process includes ozonizing a mixture
comprising an
ethylenically unsaturated compound having between 6 to 24 carbons with an
ozone-
containing gas to form a plurality of ozonization products, cleaving the
plurality of
ozonization products under oxidative conditions in the presence of a suitable
catalyst to form
mixed oxidation products. The mixed oxidation products comprise a mixture of
C2 to C22
monocarboxylic acids and C2 to C22 dicarboxylic acids. The process further
includes
distilling the mixed oxidation products to provide a first distillate and a
first residue of the
mixed oxidation products. The first distillate comprises a mixture of C2 to
C16
monocarboxylic acids, and the first residue of the mixed oxidation products
includes the
dicarboxylic acid and a mixture of C9 to C22 monocarboxylic acids. The process
further
includes distilling the first residue of the mixed oxidation products to
provide a second
distillate and a second residue of the mixed oxidation products, wherein
second distillate
comprises the dicarboxylic acid and a fraction of the mixture of C9 to C22
monocarboxylic
acids; partitioning the second distillate between water and an organic
solvent, wherein the
water is at a temperature within the range of about 175 F, 79 C to about 230
F, 110 C;
wherein water and the organic solvent are substantially immiscible to thereby
form an
aqueous layer containing the dicarboxylic acid and an organic solvent layer
containing at
least a portion of the fraction of the mixture of C9 to C22 monocarboxylic
acids; separating
the organic solvent layer from the aqueous layer. The process further includes
isolating the
dicarboxylic acid from the aqueous layer to provide a purified dicarboxylic
acid having a
residual content of C9 to C22 monocarboxylic acids in an amount that is less
than a5 percent
by weight.
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
7
[0016] According to another embodiment of the present invention, a process
for
producing a monocarboxylic acid and a dicarboxylic acid from an unsaturated
carboxylic acid
is provided. The process comprises the steps of generating an ozone gas in an
ozone
generator; contacting the ozone gas with an unsaturated carboxylic acid feed
comprising the
unsaturated carboxylic acid in an absorber to obtain an ozonide; contacting
the ozonide with
an oxygen gas and at least one catalyst in a reactor to provide mixed
oxidation products, and
separating at least a portion of the mono carboxylic acid from the mixed
oxidation products
by distilling the mixed oxidation products to provide a first distillate and a
first residue of the
mixed oxidation products, wherein the first distillate comprises a fraction of
the
monocarboxylic acid, and wherein the first residue of the mixed oxidation
products
comprises a fraction of the dicarboxylic acid. The method further includes
purifying the
saturated dicarboxylic acid by extracting with an organic solvent in
accordance with the
processes described herein.
[0017] In accordance with another embodiment of the invention, a chemical
derivative of a dicarboxylic acid afforded by the processes claimed herein is
provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings, which are incorporated in and constitute
a part
of this specification, illustrate embodiments of the invention and, together
with the general
description of the invention given above, and the detailed description given
below, serve to
describe the invention.
[0019] FIG. 1 is a schematic representing an oleic acid ozonolysis plant
(under the
prior art).
[0020] FIG. 2 is a schematic representing an organic extractant recovery
system
according to an embodiment of the present invention.
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
8
DETAILED DESCRIPTION OF THE INVENTION
[0021] According to embodiments of the present invention, a process for
purifying a
dicarboxylic acid compound is provided. The dicarboxylic acid is derived from
a chemical
process where an unsaturated carboxylic acid is contacted with ozone to obtain
an ozonide.
The ozonide is treated with an oxygen-containing gas and at least one
oxidation catalyst in a
reactor to obtain mixed oxidation products containing a monocarboxylic acid
and a
dicarboxylic acid. The carboxylic acid mixture is purified by distilling at
least a portion of
the monocarboxylic acid in a first distillation fraction thereby leaving the
dicarboxylic acid in
a first residue of the mixed oxidation products. The residue of the mixed
oxidation products
is then distilled in a second distillation to form a second distillate and a
second residue of the
mixed oxidation products. The second distillate comprises the dicarboxylic
acid and may
contain monocarboxylic acid impurities at levels of between about 10% to about
30% by
weight, where a significant portion of these impurities cannot be effectively
removed from
the dicarboxylic acid portion by distillation. As such, additional
purification of the saturated
dicarboxylic acid is effected by performing an extraction with an organic
solvent. The
second residue of the mixed oxidation products includes various tars and metal
soaps derived
from the at least one oxidation catalyst.
[0022] According to one embodiment, the ozonolysis may be performed on
ethylenically unsaturated compounds. Suitable ethylenically unsaturated
compounds are not
particularly limited by their source and may include any number of carbon
atoms, such as
between 6 to 24 carbon atoms. For example, the ethylenically unsaturated
compounds may
include an ethylenic ally unsaturated compound having between 12 to 20 carbon
atoms.
Accordingly, an ethylenically unsaturated compound may have 18 carbon atoms.
Further, the
ethylenically unsaturated compounds may include additional functional groups,
such as
carboxylic acids. The ethylenically unsaturated compounds may be derived from
animal or
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
9
plant sources. Accordingly, the ethylenically unsaturated compounds include
fatty acids,
including those obtained from palm oil or tallow. In one example, the
ethylenically
unsaturated compounds include oleic acid.
[0023] After reacting a C6 to C24 ethylenically unsaturated compound with
an ozone-
containing gas, a plurality of ozonization products are formed, which are
cleaved under
oxidative conditions in the presence of a suitable catalyst to form mixed
oxidation products,
which comprise a mixture of C2 to C22 monocarboxylic acids and C2 to C22
dicarboxylic
acids. For example, the mixture of carboxylic acids may include C2 to C16, C5
to C9, or C6
to C18 monocarboxylic acids. The mixture of carboxylic acids may include C2 to
C16, C5 to
C9, or C6 to C18 dicarboxylic acids, for example. According to an exemplary
embodiment,
the ozonolysis may be performed on oleic acid to thereby produce pelargonic
acid, which is a
saturated C9 monocarboxylic acid, and azelaic acid, which is a saturated C9
dicarboxylic
acid.
[0024] In order to isolate a desired dicarboxylic acid, such as azelaic
acid, the mixed
oxidation products, which may be oleic acid derived, are distilled under a
first set of
distillation conditions to provide a first distillate comprising a portion of
the C2 to C22
monocarboxylic acids, which can include pelargonic acid, and a first residue
of the mixed
oxidation products. The first residue of the oxidation products comprises the
desired
dicarboxylic acid (e.g., azelaic acid), along with a plurality of impurity
acids, which may
include a mixture of C9 to C22 monocarboxylic acids, as well as other
dicarboxylic acids.
[0025] The first residue of the mixed oxidation products is then subjected
to a second
distillation performed under a second set of distillation conditions to
provide a second
distillate and a second residue of the mixed oxidation products. The second
distillate
comprises the desired dicarboxylic acid and a first fraction of the plurality
of impurity acids.
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
The impurity acids are by-product acids (BPA), which may include a mixture of
C9 to C22
monocarboxylic acids.
[0026] In order to separate the azelaic acid from the bulk of the impurity
acids,
further processing includes an aqueous extraction using an organic solvent, as
explained next.
The aqueous extraction includes partitioning the second distillate in water
and/or between
water and an organic solvent that is substantially immiscible with water.
Accordingly, the
second distillate is combined with hot water to form a concentrated aqueous
solution of the
second distillate. If desired, a portion of the by-product acids (BPA) that do
not dissolve in
the concentrated aqueous azelaic acid solution can be decanted from the
concentrated
aqueous solution in a separate extractor or decanter prior to subsequently
extracting the
concentrated aqueous solution cut with an organic solvent or simply
transferred to an
extractor. In either case, the concentrated aqueous solution of second
distillate is then mixed
with the organic solvent, where the azelaic acid is retained in the water
layer, i.e., the aqueous
phase, along with a second fraction of the plurality of impurity acids, such
as various water-
soluble short chain (e.g., C4 to C8) dicarboxylic acids. The organic solvent
soluble by-
product acids (e.g., C9 to C22 monocarboxylic acids) are extracted into the
organic solvent.
[0027] With reference to FIG. 2, the crude azelaic acid (i.e., the second
distillate)
from storage tank 58 may be combined with water in a hot water tank 80 to make
a
concentrated aqueous solution of crude azelaic acid, which may then be fed
into decanter 81,
where a portion of the by-product acids (BPA) that do not dissolve in the hot
aqueous azelaic
acid solution can be decanted from the concentrated aqueous solution, prior to
transfer to the
extractor 64, where the concentrated aqueous solution cut is then mixed with
the organic
solvent. According to one embodiment, the concentrated aqueous solution of
crude azelaic
acid may be directly fed into extractor 64. According to one embodiment, the
azelaic
extractor 64 may be a York-Scheibel extractor, which is a counter-current,
multistage,
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
11
continuous liquid-liquid extractor. In one embodiment, the York-Scheibel
extractor has
about 10 to about 60 stages. For example, the York-Scheibel extractor may have
10, 20, 30,
40, 50, or 60 or more stages.
[0028] Azelaic acid is soluble in hot water. The extraction temperature of
the water
may be within the range of about 175 F, 79 C to about 230 F, 110 C. The
extraction may be
performed under ambient pressure or under elevated pressure conditions. The
organic
solvent is not particularly limited to any specific solvent, but should be
substantially
immiscible with water under the operating conditions. For example, the organic
solvent may
have water solubility of less than 0.5 grams per liter at 20 C. Further,
suitable organic
solvents have boiling points greater than the temperature of the extracting
water under the
extraction pressure.
[0029] Exemplary organic solvents that can be used in the process include,
but are not
limited to, an aliphatic or aromatic hydrocarbon solvent and/or mixtures
thereof in which the
impurities present in the crude dicarboxylic acid are soluble and in which the
dicarboxylic
acid is substantially insoluble. Examples of such aliphatic solvents include,
but are not
limited to, linear and branched, cyclic and acyclic alkanes such as pentane,
hexane, heptane,
octane, 2,2,4-trimethylpentane, cyclopentane, cyclohexane, methylcyclopentane,
methylcyclohexane,;alkenes such as pentene, hexene, heptene, cyclopentene,
cyclohexene,
methylcyclopentene, methylcyclohexene and the like and liquefied hydrocarbons
that are
normally gases at room temperature and pressure such as liquid propane and
liquid butane.
Examples of such aromatic solvents include, but are not limited to, benzene,
toluene, and
xylene. Solvent mixtures include, but are not limited to, petroleum
distillates such as
naphtha, heavy naphtha and petroleum ether. In one example, the organic
solvent is octane.
In another example, the organic solvent is a heavy naphtha, such as VM&P
Naphtha.
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
12
[0030] The crude azelaic acid from storage tank 58 may be combined with
water in a
hot water tank 80, where the water is at a temperature within the range of
about 175 F, 79 C
to about 230 F, 110 C, to make a concentrated aqueous solution of crude
azelaic acid, which
according to one embodiment is then fed into the extractor 64 and mixed with
the organic
solvent. Over time, the immiscible organic solvent separates from the aqueous
solution
thereby forming an extracted aqueous solution of azelaic acid and an organic
solvent layer
containing the extracted by-product acids (BPA). On discharge from the
extractor 64, the
organic solvent content of the extracted aqueous solution of azelaic acid
should be as low as
possible to avoid introducing flammable organic solvents into other parts of
the plant while
transferring the extracted aqueous solution to a crystallizer 85. A flash tank
may be used to
remove the organic solvent from the extracted aqueous solution. According to
an
embodiment, the extracted aqueous solution comprises less than 1 percent by
weight of the
organic solvent portion prior to any subsequent processing step.
[0031] The organic phase comprising the organic solvent and extracted BPA
(e.g., C9
to C22 monocarboxylic acids) can be transferred to the BPA storage vessel 67,
if desired.
However, according to an embodiment of the present invention, further
processing can be
performed to recycle the organic solvent by removing the BPA, as explained
next.
[0032] In one embodiment, the organic solvent layer comprising the C9 to
C22
monocarboxylic acids may be transferred to an organic solvent evaporator 90,
wherein the
organic solvent is separated from the C9 to C22 monocarboxylic acids by
vaporizing the
organic solvent to form an organic solvent vapor, thereby leaving the C9 to
C22
monocarboxylic acids as a residue. Any suitable conditions may be used for the
organic
solvent distillation unit. For example, organic solvent evaporator may be run
at about 250 F,
121 C to about 275 F, 135 C and atmospheric pressure. The residue containing
the C9 to
C22 monocarboxylic acids may be stored for later processing, if desired.
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
13
[0033] The organic solvent vapor, having been separated from the C9 to C22
monocarboxylic acids, is transported to a condenser 95, which condenses the
organic solvent
vapor to form the recycled organic solvent, which is then passed through a
decanter 100 to
remove entrained water, and may be collected in a recycled organic solvent
tank 105.
According to an embodiment of the invention, the recycled organic solvent
includes less than
1 percent by weight of C9 to C22 monocarboxylic acids. For example, a residual
content of
C9 to C22 monocarboxylic acids in the recycled organic solvent may be less
than 0.5 percent
by weight, or less than 0.1 percent by weight, or less than 0.05 percent by
weight.
[0034] The C9 to C22 monocarboxylic acids residue may be further processed
by
using an additional distillation unit to strip off any remaining organic
solvent prior to
discharging the residue. For example, the C9 to C22 monocarboxylic acids
residue from the
evaporator 90 may be sent to organic solvent stripper 110. The organic solvent
stripper 110
uses a carrier vapor, such as steam, to strip out any remaining solvent. Any
suitable
conditions may be used for the organic solvent stripper 110. For example,
stripper 110 may
be run at approximately about 250 F, 121 C to about 275 F, 135 C and
atmospheric
pressure. The recovered organic solvent may be combined with the first
distilled organic
solvent prior to the condenser 95, or a standalone condenser may be used. The
stripping
steam is also condensed in the condenser 95, but is then separated from the
solvent. For
example, the water and organic solvent may be separated using the decanter
100.
[0035] The recycled organic solvent is thereby rendered sufficiently pure
to then be
reused to purify the azelaic acid of sufficient purity to use in preparing
derivatives that may
be used for a number of different purposes such as lubricants, plasticizers,
lacquers,
herbicides, and skin treatments. For example, azelaic acid having a residual
content of C9 to
C22 monocarboxylic acids that is less than 0.5 percent by weight can be
achieved in
accordance with the processes described herein. In another embodiment, azelaic
acid having
CA 02841595 2014-01-14
WO 2012/103325
PCT/US2012/022709
14
a residual content of C9 to C22 monocarboxylic acids that is less than 0.1
percent by weight
or 0.05 percent by weight can be achieved.
[0036] The
apparatus and processes described herein may be useful to recycle organic
solvents used in the purification of dicarboxylic acids derived from
ethylenically unsaturated
monocarboxylic acids, such as oleic acid. As mentioned above, the apparatus
and processes
are particularly suited for use with a ozonolysis system that breaks down
oleic acid into
pelargonic acid and azelaic acid. However, the apparatus and processes may be
useful to
purify other dicarboxylic acids which can be derived from ethylenically
unsaturated
monocarboxylic acids other than oleic acid via the described ozonolysis
reaction. The
unsaturated acids may generally have between 6 and 30 carbon atoms, for
example between 8
and 24 carbon atoms, and one or more unsaturated carbon to carbon bonds. The
monobasic
and dibasic acid products that result from the ozonolysis reaction are
determined by the
location of the one or more unsaturated carbon to carbon bonds in the
unsaturated acid. The
unsaturated acids may be isolated from biological sources, such as plants,
animals, or
microorganisms. Alternatively, the unsaturated acids may be isolated from
petroleum
sources and synthetic sources. Exemplary unsaturated acids and their
respective potential
oxidation products are included in the Table below.
CA 02841595 2014-01-14
WO 2012/103325 PCT/US2012/022709
Table 1. Exemplary ethylenically unsaturated compounds and corresponding
ozonization
products.
Carbons Exemplary Unsaturated Exemplary Monobasic Exemplary Dibasic
Fatty Acid Product Product
10 Obtusilic acid Caproic acid Succinic acid
10 Caproleic acid Formic acid Azaleic acid
11 Undecenoic acid Formic acid Sebacic acid
12 Lauric acid Propionic acid Azelaic acid
14 Myristoleic acid Valerie acid Azelaic acid
16 Palmitoleic acid Heptanoic acid Azelaic acid
18 Petroselinic acid Lauric acid Adipic acid
18 Oleic acid Pelargonic acid Azelaic acid
18 Vaccenic acid Heptanoic acid Hendecanedioic acid
18 Octadecenoic acid Caproic acid Dodecanedioic acid
Gadoleic acid Undecanoic acid Azelaic acid
22 Cetoleic acid Undecanoic acid Hendecanedioic acid
22 Erucic acid Pelargonic acid Brassylic acid
24 Selacholeic acid Pelargonic acid Pentadecanedioic acid
26 Hex acosenoic acid Pelargonic acid Heptadecanedioic acid
Tricosenoic acid Pelargonic acid Heneicosanedioic acid
[0037] While the table above includes mono-unsaturated acids, it is
understood that
poly-unsaturated acids could be utilized as well. The resulting monobasic
acids and dibasic
acids, and their derivatives, may be used for a number of different purposes
such as
lubricants, plasticizers, lacquers, herbicides, and skin treatments.
[0038] While the present invention has been illustrated by the description
of one or
more embodiments thereof, and while the embodiments have been described in
considerable
detail, they are not intended to restrict or in any way limit the scope of the
appended claims to
such detail. Additional advantages and modifications will readily appear to
those skilled in
the art. The invention in its broader aspects is therefore not limited to the
specific details,
representative product and/or method and examples shown and described. The
various
features of exemplary embodiments described herein may be used in any
combination.
Accordingly, departures may be made from such details without departing from
the scope of
the general inventive concept.
