Note: Descriptions are shown in the official language in which they were submitted.
5~
PRODUCTION OF AN ACYLIUM ANION PRODUCT AND
CARBOXYLIC ACIDS AND ESTERS TEIEREFROM
3ACKGROUN3 OF I~HE INVENTION
A. Fleld of the Invention
The invention relates to the liquid phase produc-
tion of an acylium anlon product, e.g., isobu~yryl fluorid2,
by reacting a premi~ed carbon monoxide saturated anhydrous
acid solution and an organic compound capable of adding
carbon monoxide thereto.
B._ Description of the Prior ~rt
The prio~ art such as GB 942,367 and DE - 2,750,719
as a whole stresses the requirement of gas-liquid phase
systems and an aqueous acid catalys~ reac~.ion medium for
p~oduction of carboxylic acid from compounds having one or
more double bonds, or esters following by further hydrolysis
of the reaction products to produGe carboxylic acids. In
these processes, serious irreversible polymeriza-tion occurs
and the aqueous acid medium is corrosive so that expensive
equipment is required.
For example, in the prior ar~/ such as in Koch
U.S. Patent No~ 2,831,877, acid fluorides can be formed by
reacting an olefin with carbon monoxide and anhydrous
hydrogen fluoride. This reaction is a dual phase reaction
with the carbon monoxide in the gaseous state and the olefin
and hydrogen fluoride remaining in the liquid state. As
with most dual phase reactions,problems arise due to the
requirement of additional mixing and replenishing the carbon
monoxide into the liquid as it is used up. This is extremely
significant in that the olefin dimerizes or polymerizes
under ~hese conditions.
The problems of the prior art are overcome by
the use of a liquid phase anhydrous system to form the
acylium anion product by the process or reaction conditions
described herei~, or the carboxylic acids bv the process
described herein~
SUMMARY OF THE INV~NTION
.
Carbon monoxide and an anhydrous acid describe.d
herein, e.~g., hydrogen fluoride are premixed in a first
reac~or to form a liquid phase pre~erably saturated with
car~on monoxide which is rapidly reacted in a second reactor
with an organic compound described herein capable of adding
carbon monoxide thexeto, e.g., propylene, under reaction
conditions of a liquid phase whereby an acylium anion product
forms, e.g., isobutyryl fluoride in substantial yields. The
acylium anion product, e.g., isobutyryl fluoride, is further
reacted with excess water to form carboxylic acid, e.g.,
isobuty~ic acid. The acid can be oxydehydrogena~ed to an
unsaturated acid, e.g., metAacrylic acid as described herein.
DETAILED DESCRIPTION OF THE DR~WINGS
Fig. 1 is a di~agram of the solubility of carbon
monoxide in anhydrous hydrogen fluoride.
Fig. 2 is a schematic diagram of a reactor for the
process of the present invention.
DESCRIPTION OF TH~ INVENTION
The disclosed novel process ~or producing an
acylium anion product and/or a carboxylic acid and/or ester
therefrom comprises the following steps:
(a) Forming in a first reactor a liquid mixture
comprlsed o~ carbon monoxide dissolved in an
anhydrous acid described herein, eOg.,
hydrogen fluoride, preferably the anhydrous
acid is saturated with carbon monoxide,
(b) Reacting in the liquid phasP in a second
reac~or under conditions whereby an acylium
57~
-- 3 --
anion product forms the liquid mixture frorn
the first reactox of CO di.ssolved in the
anhydrous acid with a llquid mixture com-
prised of an organic compo~md capable of
addin~ carbon monoxide thereto, described
herein, e.g., propylene, to form a produc~
m.ixture comprised of the acylium anion
product, e.g., isobutyryl fluoride.
In one embodiment of the invention, the process
fur~her comprises the s~ep of hvdrolyzing the acylium anion
product, e.g.~ isobutyryl fluoride, ~o form the corres~onding
carboxylic acid, e.g., isobutyric acid, under conditions
whereby the carboxylic acid forms and the anhydrous acid is
regenerated. Preferably the carboxylic acid is separated
from the hydrolyzed mixture, and the remaining hydrolyzed
mixture, absent o~ any deleterious amount of water and other
deleterious materials comprised of anhydrous acid, e.g.,
hydrogen fluoride, and/or carbon monoxide, and/or unreacted
acylium anion product, e.g., isobu~yryl fluoride, is recycled
~o the liquid mixture of anhydrous acid an~ carbon monoxide.
In another embodiment of the invention~ acrylic
acid and/or methacrylic acid is produced from the propionic
acid and/or isobutyric acid ~y oxydehydrogenation as
described herein in the ~apor phase, in the presence of an
oxygen-con~aining gas, air or oxygen itself, water, at a
temperature from 30C to 500C, and at a pressure from 0.5
atmospheres to two (2) abmospheres in the presence of a
catalyst described herein comprised of iron, ~hosphorous,
and oxygen defined by the empirical formula FePxO~, where
relative to one (1) atom of iron, x represents from 0.25 to
3.5 atoms of phosphorous and z represents the number of
oxygen atoms required to satisfy the ~alence xequirements
of the catalyst. Methyl or other alkyl esters or acrylic
acid and/or me~hacrylic acid are foxmed by esterifying the
acrylic and/or methacrylic acid.
REACTANTS
The carbon monoxide may be from any source, but
must be substantially free from water; ~hat is, contain less
than 1,000 ppm of water. The carbon monoxlde may be dlluted
with other substances which do not interfere with the reac-
tion. For example, dry synthesis gas may be used or dry
coal con~ustion gases may be used. It is preferred that
dry carbon monoxide itself be used.
~he organic compound ca~able o reacting with
carbon monoxide and the anhydrous acid may contain other
compounds and/or very small amounts of water, eOg., less than
1,000 ppm of water, which do not interfere with the liquid
phase reaction and/or cause a dual phase to occur. The
organic compounds may be organic esters or isopropanol
described hereln which split to fo~m the acid and an acylium
anion product or organic compounds having at least one
unsaturated ~ond capable of adding carbon monoxide thereto
as described herein.
Examples of these organic esters are represen~ed
o
by the general formula R - C - O - R'; wherein R is an alkyl
of up to five carbon atoms; such as methyl, ethvl, pentyl.
Preferably -the alkyl is methyl, ethyl, propyl, isopropyl,
with ethyl an~ isopropyl being highly preferred, and
isopropyl being especially preerred. R' is an alkyl of from
two to five carbon atoms, such as ethyl, propyl, pentyl.
Preferably R' is ethyl or isopropyl, with isopropyl being
the most preferred.
Although any one of the esters mentioned herein
may be used, it is ~referable if an ester is used to use
isopropyl isobu~yrate (2-propanol 2-methylpro~ionate), ethyl
isobutyrate (ethanol 2-methvlpropionate), isopropyl
propionate (2-propanol propionate) or ethyl propionate
(ethanol propionate). But isopropyl isobutyrate (2-propanol
3~
2-methyl~ropionate) is es~ecially preferred when an ester
is used in the process described herein.
Examples or organic compounds having at least one
unsaturated bond capable of adding carbon monoxide thereto
~hich may be used in the process described herein are
olefins oi up to twenty carbon atoms having at least one
double bond capable o~ adding carbon monoxide there~o, such
as: ethylene, propylene, butenes, dodecene, 1,3~butadiene,
1,4-pen~adiene, 1,5-hexadiene. Ethylene and propylene are
preferred, and propylene is highly pre.~erred. The alkenes
may be substituted with alky~ or aryl cycloalkyls, or other
substitutes which do not interfere in ~he process described
herein.
Although all of the organic compolmds described
herein may be used in the process descri~ed herein, propylene,
however, i5 especially preferred.
The acids used for the preferred process to the
acylium ani~n described herein should be substantially free
rom water; that is, anhydrous. The term "anhydrous'' as used
herein and in the claims refers to acids which are substan-
tially free from water, e.g., less than 1,000 ppm of water,
or if water is present, it does not interfere with the reac-
tion to form-the acylium anion, or the carboxvic ester
therefrom.
~he anhydrous acids which may be used for the
described process are:
hvdrogen fluoride (hydrofluoric acid) ~HF)
hydroaen chloride (hydrochloric acid) (~Cl)
hydrogen fluoride ~ boron trifluoride (HF-3F3)
or mixtu~res thereof, but preferably the individual acids.
Preferably the anhydrous ac.id for the process
described is selected from anhydrous hvdrogen fluoride and
anhydrous hydrogen chloride. However, ~he most preferred
anhydrous acid for the process described herei.n is hydro~e~
fluoride (hvdrofluoric acid).
' ;
Reaction Conditions to Form the Acylium Anion Product
The reaction of carbon monoxide, with an organic
compound described herein and an anhydrous acid descrihed
herein, can occur at temperatures of from zero degree Centi-
grade (0C) to ninety degrees Centigrade (90C), the uppertemperature being determined bv side product formation. For
the reaction between the preferred reactants described herein,
the temperature can be from forty degrees Cen~igrade (40~C)
to sixty degrees Centigrade (60CC), but preferably it is at
about fifty degrees Centigrade (50C). The carbon monoxide
pressure can varv from thirty-four (34) bars (500 psia) to
three hundred for~y (340) bars (5,000 psia), and preferably
it is from 2,500 psia to 2,000 psia. The pressure belng
increased as required for the solubility o~ carbon monoxidP
in the anhydrous acid, as for example r shown in Figure l,
which shows the increase in the amount of carbon monoxide
dissol~ed in anhydrous hydrogen fluoride as the pressure and
temperature increases.
The mole ratio of anhydrous acid to ~he organic
compound described herein should be from l:l to 100:1, but
generally it is from lQ:l to 20:1 and preferablv about 15:1.
The mole ratlo of carbon monoxi~e to the organic compound is
from l:l to 5:1 or higher, but preferably it is from l.S:l
to l:l, and the maximum corresponds to the saturation limit
of carbon monoxide in the reaction mixture during and at the
end of the reaction.
All of the carbon monoxide (CO) and anhydrous acid,
e.g., anhydrous hydrogen fluoride, which is to be reacted
with the orqanic campound, e.g., propylene, should be
thoroughly mixed in the first reactor to form a liquid
mixture in which the CO is dissolved therein, preferably
the li~uid mixture is saturated with the CO prior to reacting
with the organic compound described herein, e.g., propvlene,
then the organic compound in the liquid phase is rapidly
reacted, while mixing with the premixed carbon monoxide and
acid in the second reactor. Generally, the reaction,
depending upon ~he pressure and the temperature, will occur
within mlnutes ~o form an acylium anion product, e.g.,
isobutyryl fluorideO The orqanic compound itself can be
diluted with carbon monoxide or other inert diluents, eOg.,
methane, ethane, propanol, etc., in the li~uid phase to form
a liquid mixture comprised of the organic compound, e.g.,
propylene, and CO, and/or inerts prior to reaction with the
liquid mixture of anhydrous acid diluted with carbon monoxide.
The second reactor can be a semi-batch reactor, plug flow
reactor, back mix reactor ~CSTX), or other reactor known to
those skilled in the art; but the preferred reactor is a
plug flow reactor.
After the reaction to form the acylium anion is
complete, which depends upon the reaction conditions as
known to those skilled in the art, from one (1) to one
hundred (100) percent of the acylium anion product formed is
separated from the product mixture. Preferably, from eighty
20 (80) to one hundred (100) percent of the acylium anion
product is separated, and the remaining product mixture is
recycled to the first or second reactor; that is, carbon
monoxide, anhydrous acid, and the organic ccmpound described
herein. Or, from one (1) to one hundred (100) percent
25 (preferably from eighty (80) to one hundred (100) percent),
of the anhydrous acid is separated from the ~roduct mixture
containing the acylium anion produc~ after the reaction to
form the acylium anion is complete and the separated anhy-
drous acid is recycled back to the first reactor for further
mixing with carbon monoxide.
The separation can be by any of the known methods
of separation, such as distillation.
The H drolvsis Process to Form the Corr~s ondin CarboxYlic
Y , ~ P g
Acid
The hydrolysis reaction of the acylium anion addi-
tion product, e.g., isobutyryl fluoride, with excess water
can occur at temperatures from ~wenty degrees Centigrade
(20C) to one hundred fifty degrees Centigrade (15CC) and
at pressures from 14.7 psia to 5,000 psia, but normally it
occurs at temperatures from forty degrees Centigrade (40C)
to seventy degrees Cen-tigrade (70C) and pressures at 500
~sia ~o 3,000 psia. The temperature and pressure being set
to avoid the decomposition of the intended ~roducts.
The ~otal amount of water to be added, may be
lnjected into the reaction mixture after the reaction to
form acylium anion is complete. The hydrolysis step is
exothermic; and, thus, cooling may be required.
The Esterlfication Process to Form_the Carboxylic Acid Esters
The esterification reaction of the acylium anion
product, e.g., isobutyryl fluoride, wlth an alcohol, particu-
larlv, can occur at tem~eratures from twentv degrees Centi-
qrade (20~C) to one hundred fifty degrees Centigrade (150C)
and at pressures from 14.7 psia to 5,000 psia~ but normaily
it occurs at temperatures from forty degrees Centigrade
(40C) to seventy degrees Centigrade (70C) and pressures at
50 psia to lO0 psia. The temperature and pressure being set
to avoid the decomposition of the intended products, and to
facilit~te product separations.
It is preferred that the reactants be stirred
during esterifica~ion. In many cases, when ra~id mixing is
used, the esterification reaction with the concurrent
regeneration of the anhydrous acid, e.g., HF, can be
completed within seconds to minutes.
From one ~l) to one hundred (lO0) percent (prefer
ably from eightv (80) to one hundred (lO0) percen-t) or the
7~
anhydrous acid is seoarated from the esterifica~ion product
mixture and i5 recycled back for reac~ion to ~orm more
acylium anion produc~. The recycle stream may contain small
amounts of unseparated, unesterified acylium anion product
5 and/or carboxylic acid ester and/or unreacted organic
compound .
The separation can be by any of the known methods
of separation, such as distilla-tion or solvent extraction.
Preferably, distillation is used.
The carboxvlic acid of propionic acid or isobutyric
acid formed from acylic anion product, e.g., propionyl
fluoride or isobutyryl fluoride, after hydrolysis as
described herein can be oxydehydrogenated by the ~rocess
15 described in U.S. patents 3,5~5,248; 3,585,24~; 3,585,250;
3,634,494; 3,652,65~; 3,660,514; 3,766,191; 3,781,336;
3,784,483; 3,8S5,279; 3,917,673; 3,948,959; 3,968,1~9;
3,975,301; 4,029,695; 4,061,673- 4,081,465- ~,088,602;
British Patent 1,447,593.
TEIE REP~CTOR TO FORM THE ACYLIUM ANIO~ PRODUCT
The reaction can be carried out in any reactor
which has a means for forming a liquid phase mixture of
carbon monoxide and anhydrous acid, e.g., a pressurized
mixin~ tank, and a means for separately contacting the
liquid phase mi.xture of carbon monoxide and anhvdrous acid
with a liquid ohase comprised of an organic compound and
reacting (e.g., a tubular reactor) so as to form a product
mixture containing an acylium anion produc~. It can further
comprise elther a means for separating the acylium anion
product from the product mixture, e.g., a distillation
column, or a means for separating the acylium anicn product
from the product mixture, and separately hydrolyzing or
5~
-- 10 --
esterifying the separated acylium anion produc-t rom the
product mixture -to a carboxylic acid or ester (e.g., a
distillation column connected to a reactor) or a means for
separately hydrolyzing or esteri~ying -the acylium anion
S product in ~he product mixture to a carboxylic acid or ester.
A means for separating the carboxylic acid or ester ca~ be
attached to the reactor (e.g., distillation column). Means
for introducinq the reactants -to reac~or (e.g., pumps) can
be attached to the reactor.
Figure 2 shows a schematic diagram of a typical
reaction system for use in the present invention. Such a
syste~ should include sources of the ac d, e.g., hydrofluoric
acid 10, a source o carbon monoxide 11 and a source of the
organic compound, e.g., propylene 1.2. The carbon monoxide
is metered by metering means such as a metering ~alve 13
through line 14 into a pressurized mixing tank 15 which is
maintained under pressure. The acid, e.g., hydrofluoric
acid, is injected into the mixing tank through line 16 by
inserting means such as pump 17. The pressurized mi~ing
tank 15 should also be equipped with agit~tion means such
as a stirrer 18. The pressurized mixing tank may generally
have a liquid phase 19 and a gaseous phase 20 wherein the
carbon monoxide not dissolved in the acid, e.g., hydrogen
fluoride, is maintained.
The Liquid phase comprises a mi~ture of carbon
monoxide and hydrogen fluoride. This miYture is transferred
through line 21 under pressure to the inlet of a reactor
such as a plug flow or tubular reactor 22.
~he organic compound, such as propylene, is trans-
ferred through a llne 23 into the reactor inlet via a
liquid-llquld mlxing nozzle. A meterlng oump 24 should also
be used to inject the organic compound at the desired rate
and at the pressure of the reac~lon~
The reactor of the present in~ention must be
capable of maintaining the hydraulic pressure of the system
o ~
and must allow sufficient residence ~ime for the reaction to
occur. The reac-tion time generally will vary based on the
reac~ion temperature. Increased temperature increases the
rate of reaction. Generally, the reactlon time should take
no longer ~han approxima~.ely 120 seconds altnough it will be
obvious to one of ordinary skill in the art ~o determine
exactly what the preferred reaction time should be for partic-
ular reagents, temperatures and ~ressures.
The reagent mixture comprising the acid, hydrogen
~luoride - car~on monoxide solution and the organic compound
passes through the reactor and exits through a pressure
release valve or let down ~alve 25.
This is a simple schematic diagram of a reaction
svstem suitable for the present invention. Various types of
reactors could be used for the present in~ention and one of
ordinary skill in the ar~ would have no trouble in designing
a particular reactor suitable or the particular intended
purpose.
After the reactants have passed the let down valve
25, the addition step of hydrolysis or esterification of the
acylium anion product, such as an acyl fluorlde, e.~.,
isobutyryl fluoride can be conducted in a second reactor 26
or in an extension of the tubular reactor 22. The hydrolysis
is conducted simply by adding water to the stable organic
carbon monoxide acid acion product, e.g., the acid fluoride,
e.g., isobutyrvl fluoride. This produces the car~ox~lic
acid, e.g., isobutyric acid, and acid, e~g., hydrogen
fluoride, which then can be separated by means such as a
distillation apparatus 27 and used again if desired to
produce additional stable organic carbon monoxide acid anion
addition product. The acid can also be reacted with other
compounds such as an alcohol to form an ester.
It is extremely important in the present in~ention
to maintain the proper amount of carbon monoxide in solution.
From the chart in Figure 1 the amount of carbon monoxide
- 12
which can be dissolved in anhydrous hydrogen fluori~e can be
determined. This data were empirically determlne~ and one
of ordinary skill in the art should be able to likewise
determi.ne the solubility of carbon monoxide in anv anhydrous
or substantially anhydrous acid a~ a particular tem~erature
and a particular pressure. Based on ~he mol~r amount of the
organic compound whic~l is intended to be reacted, the amount
of carbon monoxide needed for the reaction can ~e ~etexmined.
For example, as s~ated above, the desired range of molar
lU ratios of organic compound to carbon monoxide to acid is
~ S:l-100 and the preferred ratio is 1~ 15, ~articularly
for propylene, carbon monoxide, and anhydrous hydrogen
fluoride.
Other informa~ion required are the reaction condi-
tions desired, e.g., the pressure and the temperature of thereactor. From this the molar percentage o~ carbon monoxide
dissolved in the acid, e.g., hydrogen fluoride, can be
determined. From this, the amount of acid, e.g., hvdrogen
fluorlde, solution required to supply sifficient carbon
~0 monoxide to react with the organic compound can also be
de~ermined.
For example, if the intended reaction conditions
are 5,000 psig and 80C, it is known from the Figure 1 or
one could em2irically determine that under these conditions
L4 pds. of carbon monoxicle will dissolve in 100 lbs. of
anhydrous hydrogen fluoride.
More specifically, take for e~ample the formation
of isobutyryl fluoride from propene where the intended flow
rate of propene is 226 lb-moles/hr~ or 9,515 lb/hr. It is
pxeferable to have about a 10 percent excess of carbon
monoxide to insure sufficient carbon monoxide availability
for the olefin~ Therefore, aoproximately 24~ lb-mole/hr.
(6,963 lb/hr.) of carbon monoY~ide is required. Since the
solubility of carbon monoxide in hydrogen fluoride at the
35 reac~ion conditions is 14 lb. CO/100 pd. ~F it is kno~n tha~
- ~3 -
49,736 pds/hr. of ~F is sufficient to dissolve the carbon
monoxide needed to react with the propene. This equals
2,486 lb. mole/hr making a molar ratio of hydrogen fluorlde
to propene of ll:l.
S At 3,000 psig and 80C~ 9 lbs. of carbon monoxide
would be dissolved in 100 lbs. of hydrogen fluoride. There~
fore, the minimum mole ratio in this situation calculates to
17:1 HF to ~ropene.
Once the proper proportions of organic compound and
acid carbon monoxide solutions are determined the carbon
monoxide and acid solution is injected into the mixing vessel
at the desired reaction conditions. The solution of carbon
monoxide in acid, e.g., hydrogen fluoride, which is formed
in the mixing vessel is metered into the reactor. The mixing
vessel must be maintained at a high enough ~emperature and
pressure to kee2 the carbon monoxide in solution. The
desired amount of organic compound, e.g., propylene, is also
metered into the reactor where it contacts and mixes with
the solution of carbon monoxide in acid, e.g., hydrogen
fluoride.
The reagents are passed through the reactor while
maintaining the pressure and tem~erature. Since this reac-
tion is generally exot~ermic, cooling jacke~s may be required
for the reac~or. Thus, .~or carbon monoxide, hydrogen
fluoride, propylene reactlon this is ~articularly important
since this reaction should be conducted a-t less than 90C.
The reagents once having passed through the reactor
are released through a let down valve and further purified
and if requîred, further reacted. A typical reaction as
described ~reviously would be the hydrolysis of the stable
organic carbon monoxide and anion addition ~roduct, e.g.,
~cid fluoride to form a carboxylic acid and the acid, e.g.,
hydrogen fluoride.
The following examples will illustrate the 2rocess
and reactor scheme described herein.
- 14 -
Example 1
..
The reactor in the presen-t example comprises a 1-
liter Monel autoclave equipped with a turbine blade stirrer
with two inlets and a bottom outlet connected to a reactor.
The reactor was a tubular reactor comprising a 1/2-inch
diameter tube 40 feet in length connec-ted at one end to the
outlet of the autoclave and at the exhaust end to a let down
valve. The reaction temperature was maintained at approxi-
mately 30C and ~he pressure was maintained at 3,000 psig.
In this reaction propene was reacted to form
isobutyryl fluoride. The carbon monoxide was injected into
the autoclave at a rate of 3.5 g. mole/hr. and the hy~rogen
fluoride was injected at a rate of 55 g. mole/hrO and mixed
therein to form a liquid phase of carbon monoxide in hydrogen
fluoride which was injected into the tubular reactor. The
flow rate of propene into the tubu~ar reactor was 2.6 g.
mole/hr. The total flow rate of reagents through the tubular
reactor was 1,198 g. per hr. Using this method 2.05 g.
mole/hr. of isobutyryl fluoride was formed. Remaini~g in the
efiluent w re 1.0 g. mole/hr. carbon monoxide, 52.4 g. mole/
hr. hydrogen Eluoride and a trace of propene. The remaining
effluent comprised other undesixable organics. The selec-
tivity of this reaction to isobutyryl fluoride was approxi-
mately 75 percent.
2s While the invention has been described with refer-
ence to specific de~ails of cextain illustrative embodiments,
it is not intended that it shall be l.imited thereby except
insofar as such details appear in the accompanying c]aims.
