U.S. patent application number 17/476752 was filed with the patent office on 2022-03-17 for direct conversion of esters to carboxylates.
This patent application is currently assigned to Niacet Corporation. The applicant listed for this patent is Niacet Corporation. Invention is credited to Kelly Brannen, David J. Harrigan, Stanley A. Sojka, Donal S. Tunks.
Application Number | 20220081384 17/476752 |
Document ID | / |
Family ID | |
Filed Date | 2022-03-17 |
United States Patent
Application |
20220081384 |
Kind Code |
A1 |
Brannen; Kelly ; et
al. |
March 17, 2022 |
DIRECT CONVERSION OF ESTERS TO CARBOXYLATES
Abstract
A calcium carboxylate is prepared by reacting water, calcium
oxide, and a compound of formula (I): ##STR00001## wherein R is a
C.sub.1-C.sub.3 alkyl and R.sub.1 is a C.sub.1 or C.sub.2 alkyl.
The reaction solution is heated to remove an amount of a co-product
from the reaction solution. The calcium carboxylate may be
recovered in a solid form from the reaction solution.
Inventors: |
Brannen; Kelly; (North Palm
Beach, FL) ; Harrigan; David J.; (Lewiston, NY)
; Tunks; Donal S.; (Grand Island, NY) ; Sojka;
Stanley A.; (Grand Island, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Niacet Corporation |
Niagara Falls |
NY |
US |
|
|
Assignee: |
Niacet Corporation
Niagara Falls
NY
|
Appl. No.: |
17/476752 |
Filed: |
September 16, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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63079683 |
Sep 17, 2020 |
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International
Class: |
C07C 51/41 20060101
C07C051/41; C07C 51/47 20060101 C07C051/47 |
Claims
1. A process for producing calcium propionate comprising: a.
reacting water and calcium oxide to obtain a slurry; b. reacting
the slurry with methyl propionate, wherein the calcium oxide is
reacted in a molar excess compared to the methyl propionate, to
obtain a reaction solution; c. heating the reaction solution to
remove an amount of methanol from the reaction solution; d.
neutralizing the reaction solution to a pH of from 7.0 to 9.5 by
adding propionic acid; and e. filtering the reaction solution.
2. The process according to claim 1, further comprising adding
nitrogen gas to the reaction solution during heating of the
reaction solution.
3. The process according to claim 1, further comprising recovering
the calcium propionate in a solid form from the filtered reaction
solution.
4. The process according to claim 3, wherein the solid calcium
propionate has a level of purity of 98.5% or greater.
5. The process according to claim 1, wherein the pH is from 7.0 to
8.0.
6. The process according to claim 1, wherein the filtered reaction
solution contains from 23% to 28% (w/w) calcium propionate.
7. The process according to claim 1, wherein step b. is conducted
at a temperature of from 50.degree. C. to 100.degree. C.
8. A process for producing a calcium carboxylate comprising: a.
reacting water, calcium oxide, and a compound of formula (I):
##STR00007## wherein R is a C.sub.1-C.sub.3 alkyl and R.sub.1 is a
C.sub.1 or C.sub.2 alkyl, to obtain a reaction solution; and b.
heating the reaction solution to remove an amount of a co-product
from the reaction solution.
9. The process according to claim 8, further comprising: c.
filtering the reaction solution.
10. The process according to claim 8, wherein the compound of
formula (I) has fewer than six carbon atoms.
11. The process according to claim 8, wherein the calcium oxide is
reacted in a molar excess compared to the compound of formula
(I).
12. The process according to claim 8, wherein the compound of
formula (I) is methyl propionate.
13. The process according to claim 8, wherein the compound of
formula (I) is ethyl propionate, methyl butanoate, or methyl
acetate.
14. The process according to claim 8, further comprising adding
nitrogen gas to the reaction solution during heating of the
reaction solution.
15. The process according to claim 8, further comprising recovering
the calcium carboxylate in a solid form from the filtered reaction
solution.
16. The process according to claim 15, wherein the solid calcium
carboxylate has a level of purity of 98.5% or greater.
17. The process according to claim 8, further comprising
neutralizing the reaction solution to a pH of from 7.0 to 9.5 by
adding an acid.
18. The process according to claim 17, wherein the pH is from 7.0
to 8.0.
19. The process according to claim 9, wherein the filtered reaction
solution contains from 23% to 28% (w/w) calcium carboxylate.
20. The process according to claim 8, wherein step a. is conducted
at a temperature of from 50.degree. C. to 100.degree. C.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to processes for the
production of a calcium carboxylate directly from an ester or
anhydride.
BACKGROUND OF THE INVENTION
[0002] Calcium carboxylates are useful in the production of the
corresponding carboxylic acids. Calcium carboxylates also have
other beneficial applications. For example, calcium acetate is used
as a thickening agent, such as in cake batters, puddings, and pie
fillings, as buffers in controlling pH of food during various
stages of processing as well as in the finished product, as a
preservative to prevent microbial growth, and as a calcium
supplement in pet products. In addition, calcium propionate is used
on a large scale as a preservative in the foodstuffs sector,
particularly in baked goods, and as a preservative and nutritional
supplement in animal feeds.
[0003] There is recent interest in short-chain fatty acids because
of their beneficial effects on gut microbiome. Moreover, acetates,
propionates, butyrates, and lactates, for example, have shown
antimicrobial properties which have been commercially useful.
[0004] Calcium carboxylates are typically prepared by the
conventional methods for synthesizing carboxylic acid salts, for
example by reacting a carbonate, hydroxide, or oxide with a
concentrated or dilute carboxylic acid. Calcium propionate, for
instance, is typically produced from propionic acid and
calcium.
[0005] Given the many and wide variety of uses for calcium
carboxylates, there is a need for improved processes for their
production. Particularly, there is a need for improved processes
that can be performed quickly, result in high yields, consume less
energy, and/or that generate minimal waste.
SUMMARY OF THE INVENTION
[0006] The invention is directed to methods of converting esters to
calcium carboxylates.
[0007] Accordingly, one embodiment is a method of reacting water,
calcium oxide, and a compound of formula (I):
##STR00002##
wherein R is a C.sub.1-C.sub.3 alkyl and R.sub.1 is a C.sub.1 or
C.sub.2 alkyl, to obtain a reaction solution and heating the
reaction solution to remove an amount of a co-product from the
reaction solution. Further, the calcium carboxylate may be
recovered in solid form from the reaction solution.
[0008] Another embodiment is a method for producing calcium
propionate comprising reacting water and calcium oxide to obtain a
slurry; reacting the slurry with methyl propionate, wherein the
calcium oxide is reacted in a molar excess compared to the methyl
propionate, to obtain a reaction solution; heating the reaction
solution to remove an amount of methanol from the reaction
solution; neutralizing the reaction solution to a pH of from 7.0 to
9.5 by adding a sufficient quantity of propionic acid; and
filtering the reaction solution. Further, the calcium propionate
may be recovered in solid form from the filtered reaction
solution.
[0009] The invention is further directed to methods of converting
anhydrides to calcium carboxylates.
[0010] Additional objects and advantages of the invention will be
set forth in part in the description which follows, and in part
will be obvious form the description, or may be learned by practice
of the invention. The objects and advantages of the invention will
be realized and attained by means of the elements and combinations
particularly pointed out in the appended claims.
[0011] It is to be understood that the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is an apparatus for the conversion of methyl
propionate to calcium propionate. The reference numbers in the
FIGURES correspond to a methanol tank 8; an integral steam coil 12;
a condenser 14; a 3-way valve 16; an agitator 18; a reactor vessel
20; a slurry pump 22; and a reflux column 30.
DETAILED DESCRIPTION OF THE INVENTION
[0013] While it was anticipated that the insolubility of
carboxylate salts containing the Ca.sup.+2 cation would be
problematic, the inventors discovered a process that directly
converts esters of formula (I) to calcium carboxylates according to
the following reaction:
##STR00003##
wherein R and R.sub.1 are, independently, selected from H, Ph, Ar,
a substituted C.sub.1-C.sub.60 alkyl, and an unsubstituted
C.sub.1-C.sub.60 alkyl.
[0014] The inventors also discovered a process that directly
converts anhydrides of formula (II) to calcium carboxylates
according to the following reaction:
##STR00004##
wherein R and R.sub.1 are, independently, selected from H, Ph, Ar,
a substituted C.sub.1-C.sub.60 alkyl, and an unsubstituted
C.sub.1-C.sub.60 alkyl.
[0015] The C.sub.1-C.sub.60 alkyl may be substituted with at least
one substituent selected from the group consisting of: F, Cl, Br,
I, At, O, S, S(O), SO.sub.2, N, P, P(O), Si, Si(O), B, Al, and
combinations thereof. Suitably, Ar is a C.sub.6 or C.sub.12 aryl or
heteroaryl optionally substituted group where the heteroatom may be
O or N and the substituent may be selected from the group
consisting of H, F, Cl, Br, I, At, SO.sub.2, NH.sub.2, NHR,
NR.sub.2 and combinations thereof, where R is as defined herein.
The number of such substituents to be substituted on the
C.sub.1-C.sub.60 alkyl may be 1, 2, 3 or 4.
[0016] In another embodiment, the C.sub.1-C.sub.60 alkyl is
substituted with at least one C.sub.1 substituent. In yet a further
embodiment, the C.sub.1-C.sub.60 alkyl is substituted with two Cl
substituents.
[0017] In one embodiment, R and R.sub.1 are, independently,
selected from the group consisting of H and an unsubstituted
C.sub.1-C.sub.10 alkyl. In another embodiment, R and R.sub.1 are,
independently, selected from the group consisting of an
unsubstituted C.sub.1-C.sub.8 alkyl. In yet another embodiment, R
and R.sub.1 are, independently, selected from the group consisting
of an unsubstituted C.sub.1-C.sub.6 alkyl. In yet another
embodiment, R and R.sub.1 are, independently, selected from the
group consisting of an unsubstituted C.sub.1-C.sub.4 alkyl.
[0018] R and R.sub.1 may each be an unsubstituted C.sub.1 alkyl. R
and R.sub.1 may each be an unsubstituted C.sub.2 alkyl. In another
embodiment, R is an unsubstituted C.sub.2 alkyl and R.sub.1 is an
unsubstituted C.sub.1 alkyl. In yet another embodiment, R is an
unsubstituted C.sub.3 alkyl and R.sub.1 is an unsubstituted C.sub.1
alkyl.
[0019] The compound of formula (I) and the compound of formula (II)
may comprise fewer than ten, eight, six, five, or four carbon
atoms. In one embodiment, the compound of formula (I) and the
compound of formula (II) comprise fewer than six carbon atoms.
[0020] The term "alkyl" means, unless otherwise stated, a straight
or branched chain, acyclic or cyclic hydrocarbon radical, or
combination thereof, which may be fully saturated, mono- or
polyunsaturated and can include di- and multi-valent radicals,
having the number of carbon atoms designated (e.g., C.sub.1-10
means one to ten carbons) and may be substituted or unsubstituted.
Examples of saturated hydrocarbon radicals include groups such as
methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl,
sec-butyl, cyclohexyl, (cyclohexyl)methyl, cyclopropylmethyl,
homologs and isomers of, for example, n-pentyl, n-hexyl, n-heptyl,
n-octyl, and the like. An unsaturated alkyl group is one having one
or more double bonds or triple bonds. Examples of unsaturated alkyl
groups include vinyl, 2-propenyl, crotyl, 2-isopentenyl,
2-(butadienyl), 2,4-pentadienyl, 3-(1,4-pentadienyl), ethynyl, 1-
and 3-propynyl, 3-butynyl, and the higher homologs and isomers.
[0021] The compound of formula (I) may be methyl acetate, ethyl
propionate, methyl propionate, or methyl butanoate. In one
embodiment, the compound of formula (I) is methyl propionate.
[0022] The compound of formula (II) may be acetic anhydride,
propionic anhydride, butanoic anhydride, or acetic propionic
anhydride. In one embodiment, the compound of formula (II) is
acetic anhydride.
[0023] The amount of calcium oxide employed in the conversion of a
compound of formula (I) can be expressed as a molar ratio of
calcium oxide to the compound of formula (I). Broadly, a molar
excess of calcium oxide compared to the compound of formula (I) may
be employed. The molar ratio of calcium oxide to the compound of
formula (I) may be from 0.5:1 to 0.75:1. A stoichiometric excess of
the calcium oxide compared to the compound of formula (I), i.e. a
molar ratio greater than 0.5:1 will result in an excess of the
calcium oxide. For example, a molar ratio of 0.75:1 corresponds to
a molar excess of 50%. The molar ratio of calcium oxide to the
compound of formula may be from 0.5:1 to 0.6:1 (an excess of
calcium oxide up to a 20% molar excess). The molar ratio of calcium
oxide to the compound of formula may be about 0.505:1 to about
0.55:1 (a molar excess of 1% to 10%).
[0024] The amount of calcium oxide employed in the conversion of a
compound of formula (II) can be expressed as a molar ratio of
calcium oxide to the compound of formula (II). Broadly, a molar
excess of calcium oxide compared to the compound of formula (II)
may be employed. The molar ratio of calcium oxide to the compound
of formula (II) may be from 1:1 to 1.5:1. A stoichiometric excess
of the calcium oxide compared to the compound of formula (II), i.e.
a molar ratio greater than 1:1 will result in an excess of the
calcium oxide. For example, a molar ratio of 1.5:1 corresponds to a
molar excess of 50%. The molar ratio of calcium oxide to the
compound of formula (II) may be from 1:1 to 1.2:1 (an excess of
calcium oxide up to a 20% molar excess). The molar ratio of calcium
oxide to the compound of formula (II) may be about 1.01:1 to about
1.1:1 (a molar excess of 1% to 10%).
[0025] The amount of water employed in the process is the amount
necessary to form a slurry; one of ordinary skill in the art is
capable of adjusting the amount of water such that the amount is
not too large to destroy the volumetric throughput of a reaction
vessel and not too small such that the slurry would be immovable,
i.e. incapable of being mixed and/or pumped. In one embodiment, the
amount of calcium hydroxide formed from the reaction of water and
calcium oxide is from 8% to 10% (w/w). In another embodiment, the
amount of calcium hydroxide formed from the reaction of water and
calcium oxide is from 10% to 30% (w/w). In still another
embodiment, the amount of calcium hydroxide formed from the
reaction of water and calcium oxide is from 30% to 60% (w/w).
[0026] The calcium oxide, water, and compound of formula (I) or
(II) may be reacted in any order and in one or more reaction
vessels. For instance, the calcium oxide and water may be reacted
in a first reaction vessel, followed by reaction with the compound
of formula (I) or (II) in a second reaction vessel. In another
embodiment, the reaction may take place in a single reaction
vessel. For instance, water may be added to the single reaction
vessel, followed by the calcium oxide, followed by the compound of
formula (I) or (II). Alternatively, calcium oxide may be added to
the single reaction vessel, followed by the water, followed by the
compound of formula (I) or (II).
[0027] One or more of the calcium oxide, water, and compound of
formula (I) or (II) may be added over a period of time instead of
in a single bolus. For instance, the compound of formula (I) or
(II) may be added to a reaction vessel over a period of up to three
hours. In one embodiment, the compound of formula (I) or (II) is
added to a reaction vessel over a period of from 30 to 120 minutes.
In yet another embodiment, the compound of formula (I) or (II) is
added to a reaction vessel over a period of 30 minutes, 45 minutes,
60 minutes, 90 minutes, or 120 minutes.
[0028] The process of the invention can generally be conducted at a
temperature sufficient to allow the reaction to proceed. For
instance, the temperature of the reaction may be from 50.degree. C.
to 100.degree. C. Temperature of the reaction may be maintained, if
necessary, by conventional techniques, such as by employing a
heating coil or mantle. The reaction time will be the time suitable
to obtain the desired conversion of the compound of formula (I) or
(II) into calcium carboxylate. Generally, the reaction time will
vary depending on process parameters including the reaction
temperature and the compound of formula (I) or (II) used. For
instance, after addition of the reactants is complete, the reaction
may be allowed to proceed for from 2 to 4 hours, or from 2 to 8
hours, or from 2 to 12 hours. The process of the invention can be
conducted as a batch, semi-batch, or continuous process depending
on the scale of the process and capital investment required.
[0029] After completion of the reaction, whereby the reaction
solution comprising the calcium carboxylate is obtained, the
process further comprises removal of an amount of one or more
co-products. The co-product may be, for instance, methanol or
ethanol. The co-product may also be propanol or butanol.
[0030] In one embodiment, an amount of a co-product can be removed
by heating the reaction solution to distill the co-product
overhead. The temperature that the reaction solution is heated to
will be any suitable temperature effective to remove the desired
amount of co-product and will be readily apparent to those of
ordinary skill in the art. The temperature may be, for instance,
from 70.degree. C. to 100.degree. C., or from 70.degree. C. to
150.degree. C.
[0031] The time cycle for distillation can be set depending on the
distillation conditions and the desired level of residual
co-product in the calcium carboxylate product, and will be readily
apparent to those of ordinary skill in the art. In one embodiment,
nitrogen gas may be introduced below the liquid level of the
reaction solution to aid in the distillation process. The distilled
co-product may be sufficiently pure to be reclaimed and reused. It
should be understood that it may not be possible to remove all
amounts of a co-product from the reaction solution and that trace
amounts of a co-product may therefore still exist in the reaction
solution as an impurity. In one embodiment, substantially all of a
co-product is removed from the reaction solution. In some
embodiments, the amount of a co-product, such as methanol, is less
than 1%, or 0.1%, or 0.01%, or 0.001%, or even undetectable
relative to the calcium carboxylate in the reaction solution
following distillation.
[0032] After completion of the distillation, it may be necessary to
adjust the concentration of the calcium carboxylate in the reaction
solution depending on the amount of water that has been removed
during the distillation. Concentration adjustment may be needed,
for instance, to ensure that all of the calcium carboxylate is in
solution and/or to adjust the concentration of the calcium
carboxylate if the final product is to be a solution. Concentration
adjustment may be effected by, for example, adding additional water
or other diluent to the reaction solution. In one embodiment, the
concentration of the calcium carboxylate is adjusted to from 23% to
28% (w/w) by adding water. The concentration of the calcium
carboxylate may be adjusted to, for instance, 25% or 26% (w/w) by
adding water.
[0033] The reaction solution may be optionally neutralized and may
also be optionally filtered. In other words, the reaction solution
may only be neutralized, only be filtered, may be both neutralized
and filtered, or may not be neutralized or filtered. The
neutralization (pH adjustment) and filtration, if both performed,
can be conducted in any order.
[0034] By way of example, the reaction solution may be filtered
using conventional equipment and techniques after the distillation
to remove excess insoluble calcium oxide, as well as any other
impurities that may be adsorbed onto the particle surfaces, as well
as any other insoluble materials present in the reactants used,
such as sand, gravel, pebbles, carbonaceous material, polymers
formed during the reaction, etc. Following the filtration, the pH
may be adjusted with carboxylic acid corresponding to the calcium
carboxylate to neutralize soluble calcium compound (forming
additional calcium carboxylate) and reach the desired pH for the
product. The pH may be adjusted to, for instance, from 7.0 to 9.5,
from 7.0 to 8.0, or 7.5, or 10.0.
[0035] In another embodiment, neutralization with carboxylic acid
corresponding to the calcium carboxylate to neutralize excess
calcium compound present is performed. Filtration of the
neutralized reaction solution is then conducted to remove remaining
insolubles.
[0036] In yet another embodiment, no filtration is conducted. The
reaction solution resulting from the distillation and optional
concentration adjustment is neutralized with carboxylic acid
corresponding to the calcium carboxylate to neutralize excess
calcium oxide present.
[0037] Once any filtration and neutralization operations are
conducted, the reaction solution may be subjected to further
processing that is dependent on the form of the final product
desired, for instance, a solution product or a solid product. For a
solution product, the calcium carboxylate product optionally has
the concentration adjusted by, for example, adding water or calcium
carboxylate, and may have one or more additional filtrations using,
for example, a polishing filter or equivalent separation
device.
[0038] For a solid product, the calcium carboxylate product may be
recovered and dried. Recovery and drying can be done utilizing any
conventional process known to one of ordinary skill in the art. For
example, the solution may be dried directly to a powder using a
spray dryer or by spraying onto dry particles in a fluid bed dryer.
In another embodiment, the calcium carboxylate product may be
crystallized by water evaporation, collection on a filter or
centrifuge, and final drying in any conventional solids dryer used
to dry wet solids. In yet another embodiment, the calcium
carboxylate solution may be processed through an agglomerator to
make a granular product.
[0039] The purity of the solid calcium carboxylate may be
determined according to standard Ca-EDTA titration as set forth in
FCC 11 ("Calcium Propionate", Food Chemicals Codex 11, page 221, US
Pharmacopeia, 2018). The purity of the solid calcium carboxylate
may be, for instance, greater than 95.0%, greater than 98.0%,
greater than 98.5%, greater than 99.0%, or greater than 99.5%, or
greater than 99.9%.
EXAMPLES
[0040] The following examples are not meant to be limiting and
represent certain embodiments of the present invention.
Example 1
Conversion of Methyl Acetate to Calcium Acetate
[0041] To a three-necked round bottom flask placed in a heating
mantle and equipped with a mechanical stirrer,
temperature-measuring thermocouple, and pressure-equalizing
dropping funnel, was added 15.2 g (0.26 mole) of lime (95%;
Specialty Minerals, Inc), followed by enough city water (159.9 g)
to make a mixable slurry. The temperature of the slurry did not
exceed 45.degree. C. To this stirred slurry was dropwise added 40.7
g (0.55 mole) of methyl acetate (96.4%; Sekisui) over a period of
1.5 hr. After this addition was complete, the reaction solution was
kept at 60.degree. for 2 hr, and then the temperature was raised to
70.degree. C. to distill volatile components into a receiver. A
total of 26.5 g of distillate was collected over a period of 2 hr.
Analysis of this distillate gave 11.8 g of water by Karl Fischer
titration. The volatile organic constituents of the distillate were
analyzed by gas chromatography to give 11.6 g of methanol (70%
recovery), and 3.1 g of unreacted methyl acetate. The remaining
contents of the round bottom flask had a pH of 6.7. Upon cooling,
solids were precipitated, removed by filtration, and dried in an
oven to give 37.9 g of calcium acetate (98.3% yield based on 92%
conversion) as a white solid. Analysis by standard Ca-EDTA
titration gave a purity of 99.8%.
Example 2
Conversion of Methyl Propionate to Calcium Propionate
[0042] To a three-necked round bottom flask placed in a heating
mantle and equipped with a mechanical stirrer,
temperature-measuring thermocouple, and pressure-equalizing
dropping funnel, was charged 1600 g of city water followed by 127.7
g (2.28 mole) of lime (95%; Specialty Minerals, Inc) added in 6
min. To this stirred slurry was dropwise added 399 g (4.53 mole) of
methyl propionate (99.95%; Lucite) over a period of 0.75 hr. After
this addition was complete, the resultant reaction solution was
kept at 60.degree. for 2 hr and had a pH of 12.2. The pH was
adjusted to 7.2 by addition of 38.8 g of propionic acid. The
temperature of the reaction solution was raised to 95.degree. C. to
distill volatile components into a receiver. A total of 575.9 g of
distillate was collected over a period of 6 hr. Analysis of this
distillate gave 426.4 g of water by Karl Fischer titration. The
volatile organic constituents of the distillate were analyzed by
gas chromatography to give 149.5 g of methanol (103% recovery). The
removal of the water by distillation was calculated to ensure that
the remaining contents of the round bottom flask was a 26% aqueous
solution of calcium propionate. This solution was filtered through
diatomaceous earth. Upon cooling, solids were precipitated, removed
by filtration, and dried in an oven to give 404.3 g of calcium
propionate (95.9% yield) as a white solid. Analysis by standard
Ca-EDTA titration gave a purity of 99.8%.
Example 3
Conversion of Ethyl Propionate to Calcium Propionate
[0043] To a three-necked round bottom flask placed in a heating
mantle and equipped with a mechanical stirrer,
temperature-measuring thermocouple, and pressure-equalizing
dropping funnel, was added 12.8 g (0.2 mole) of lime (95%;
Specialty Minerals, Inc), followed by enough city water (160.1 g)
to make a mixable slurry. The temperature of the slurry did not
exceed 45.degree. C. To this stirred slurry was dropwise added 39.7
g (0.39 mole) of ethyl propionate (99%; Aldrich) over a period of 2
hr. After this addition was complete, the reaction solution was
kept at 85.degree. for 2 hr, and then the temperature was raised to
95.degree. C. to distill volatile components into a receiver. A
total of 52.3 g of distillate was collected over a period of 4 hr.
Analysis of this distillate gave 35.3 g of water by Karl Fischer
titration. The volatile organic constituents of the distillate were
analyzed by gas chromatography to give 17 g of ethanol (95%
recovery). No unreacted ethyl propionate was detected. Solids were
removed from the round bottom flask by filtration and dried in an
oven to give 30.4 g of essentially pure calcium propionate (84%
yield) as a white solid.
Example 4
Conversion of Methyl Butanoate to Calcium Butanoate
[0044] To a three-necked round bottom flask placed in a heating
mantle and equipped with a mechanical stirrer,
temperature-measuring thermocouple, and pressure-equalizing
dropping funnel, was added 12.7 g (0.2 mole) of lime (95%;
Specialty Minerals, Inc), followed by enough city water (160.1 g)
to make a mixable slurry. The temperature of the slurry did not
exceed 45.degree. C. To this stirred slurry was dropwise added 40 g
(0.39 mole) of methyl butanoate (99%; Aldrich) over a period of 2
hr. After this addition was complete, the reaction solution was
kept at 85.degree. for 2 hr, and then the temperature was raised to
100.degree. C. to distill volatile components into a receiver. A
total of 36.8 g of distillate was collected over a period of 5 hr.
Analysis of this distillate gave 23.5 g of water by Karl Fischer
titration. The volatile organic constituents of the distillate were
analyzed by gas chromatography to give 13.3 g of methanol (105%
recovery). No unreacted methyl butanoate was detected. Solids were
removed from the round bottom flask by filtration and dried in an
oven to give 34.3 g of essentially pure calcium butanoate (94%
yield) as a white solid.
Example 5
Conversion of Methyl Propionate to Calcium Propionate at Larger
Scale
[0045] A lime slurry was prepared in a 55 gallon polypropylene tank
fitted with an agitator by the addition of 12.8 kg of lime (95%;
Specialty Minerals, Inc) into 131.9 kg of city water. This mixed
slurry was pumped into a jacketed 50 gallon glass-lined steel
reactor fitted with an agitator and condenser. To this reactor was
then added 36.9 kg of methyl propionate (99.95%; Lucite) over a
period of 0.75 hr. After this addition was complete, the reaction
solution was kept at 65.degree. C. for 1 hr. The temperature of the
reaction solution did not exceed 65.degree. C., and the final pH
was adjusted from 11.3 to 7.8 by the addition of 0.9 kg of
propionic acid. Nitrogen gas was introduced below the liquid level
at a rate of 50 SCFH as the temperature was increased to
100.degree. C. to distill off volatile components through the
condenser and into a receiving vessel. After 6 hr of distillation,
a total of 111.5 kg of distillate was collected and was analyzed as
96.4 kg of water, 13.4 kg of methanol (100% recovery), and 1.7 kg
of unreacted methyl propionate. The removal of volatiles by
distillation was calculated to ensure that the remaining contents
of the reactor was a 25% aqueous solution of calcium propionate.
This solution was filtered through diatomaceous earth. The solution
was found to contain 38.8 kg of calcium propionate (99.5% yield) of
99.8% purity as determined by standard Ca-EDTA titration.
Example 6
Conversion of Acetic Anhydride to Calcium Acetate
[0046] To a three-necked round bottom flask placed in a heating
mantle and equipped with a mechanical stirrer,
temperature-measuring thermocouple, and pressure-equalizing
dropping funnel, was added 15 g (0.25 mole) of lime (95%; Specialty
Minerals, Inc), followed by enough city water (159.9 g) to make a
mixable slurry. The temperature of the slurry did not exceed
65.degree. C. To this stirred slurry was dropwise added 24.9 g
(0.24 mole) of acetic anhydride (99%; Fisher) over a period of 2
hr. After this addition was complete, the reaction solution was
kept at 70.degree. C. for 4 hr. After this time, the pH of the
final reaction solution was 12 and enough acetic acid was added to
reduce the pH to 7.0. Analysis of the reaction solution by HPLC
showed it to be an aqueous solution of essentially pure calcium
acetate. The water was removed by evaporation to give 38.1 g of dry
calcium acetate (98.8% yield) as an essentially pure white
solid.
Example 7
Conversion System
[0047] The reactor system of this example is shown in FIG. 1. The
system comprises a 50 gallon reaction vessel 20. Water and calcium
oxide are reacted in a separate vessel (not pictured) and the
slurry is added to the reaction vessel 20. Slurry pump 22 and 3-way
valve 16 allow for the slurry to be recirculated through and
recycled back to the reaction vessel 20 to ensure complete slurry
formation. Methyl propionate (MEP) is fed into reaction vessel 20.
The contents of the reaction vessel 20 are mixed using agitator 18.
Propionic acid is added to the reaction vessel 20 in order to
neutralize any remaining calcium hydroxide.
[0048] The reactor contents are heated using an integral steam coil
12. Water and methanol vapor generated when the contents in
reaction vessel 20 are heated can be condensed at the top of a
reflux column 30 and returned from condenser 14 to a methanol tank
8. The methanol and water may be recycled to the next consecutive
batch. Once methanol has been removed, the calcium propionate
solution is transferred by slurry pump 22 to a drum filter. The
3-way valve 16 can be turned to pump thy: reactor contents out of
the reaction vessel 20 to the plant instead of being recycled to
the reaction vessel 20.
[0049] The invention is also described in the following numbered
clauses: [0050] 1. A process for producing calcium propionate
comprising: [0051] a. reacting water and calcium oxide to obtain a
slurry; [0052] b. reacting the slurry with methyl propionate,
wherein the calcium oxide is reacted in a molar excess compared to
the methyl propionate, to obtain a reaction solution; [0053] c.
heating the reaction solution to remove an amount of methanol from
the reaction solution; [0054] d. neutralizing the reaction solution
to a pH of from 7.0 to 9.5 by adding a sufficient quantity of
propionic acid; and [0055] e. filtering the reaction solution.
[0056] 2. The process according to clause 1, further comprising
adding nitrogen gas to the reaction solution during heating of the
reaction solution. [0057] 3. The process according to clause 1,
further comprising recovering the calcium propionate in a solid
form from the filtered reaction solution. [0058] 4. The process
according to clause 3, wherein the solid calcium propionate has a
level of purity of 98.5% or greater, as measured by Ca-EDTA
titration. [0059] 5. The process according to clause 1, wherein the
pH is from 7.0 to 8.0. [0060] 6. The process according to clause 1,
wherein the filtered reaction solution contains from 23% to 28%
(w/w) calcium propionate. [0061] 7. A process for producing a
calcium carboxylate comprising: [0062] a. reacting water, calcium
oxide, and a compound of formula (I):
[0062] ##STR00005## [0063] wherein [0064] R is a C.sub.1-C.sub.3
alkyl and [0065] R.sub.1 is a C.sub.1 or C.sub.2 alkyl [0066] to
obtain a reaction solution; [0067] b. heating the reaction solution
to remove an amount of a co-product from the reaction solution; and
[0068] c. filtering the reaction solution. [0069] 8. The process
according to clause 7, wherein the calcium oxide is reacted in a
molar excess compared to the compound of formula (I). [0070] 9. The
process according to clause 7, wherein the compound of formula (I)
is methyl propionate. [0071] 10. The process according to clause 7,
wherein the compound of formula (I) is ethyl propionate, methyl
butanoate, or methyl acetate. [0072] 11. The process according to
clause 7, further comprising adding nitrogen gas to the reaction
solution during heating of the reaction solution. [0073] 12. The
process according to clause 7, further comprising recovering the
calcium carboxylate in a solid form from the filtered reaction
solution. [0074] 13. The process according to clause 12, wherein
the solid calcium carboxylate has a level of purity of 98.5% or
greater, as measured by Ca-EDTA titration. [0075] 14. The process
according to clause 7, further comprising neutralizing the reaction
solution to a pH of from 7.0 to 9.5 by adding a sufficient quantity
of an acid. [0076] 15. The process according to clause 14, wherein
the pH is from 7.0 to 8.0. [0077] 16. The process according to
clause 7, wherein the filtered reaction solution contains from 23%
to 28% (w/w) calcium carboxylate. [0078] 17. The process according
to clause 7, wherein the compound of formula (I) has fewer than six
carbon atoms. [0079] 18. A process for producing a calcium
carboxylate comprising: [0080] a. reacting water, calcium oxide,
and a compound of formula (I):
[0080] ##STR00006## [0081] wherein [0082] R is a C.sub.1-C.sub.3
alkyl and [0083] R.sub.1 is a C.sub.1 or C.sub.2 alkyl, [0084] to
obtain a reaction solution; and [0085] b. heating the reaction
solution to remove an amount of a co-product from the reaction
solution. [0086] 19. The process according to clause 18, wherein
the compound of formula (I) is methyl propionate. [0087] 20. The
process according to clause 18, further comprising recovering the
calcium carboxylate in a solid form from the reaction solution
after heating.
* * * * *