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BACKGROUND OF THE INVENTION:
1. Field of the Invention:
This invention relates to the production of vinyl acetate, and more
particularly, to the production of vinyl acetate integrated in a complex
process that achieves simultaneous production of vinyl acetate.
2. Description of the Prior Art:
In the wake of "oil crisis", the price of crude oil increased greatly, and
as a result, the prices of petrochemical building blocks such as ethylene
and propylene soared. In consequence, ethylene and propylene derivatives
are losing the competitive power, and people in the industry even see the
necessity of manufacturing some derivatives from other sources by
processes other than the conventional ones. In the development of
technology for producing ethylene and propylene derivatives from sources
other than crude oil by unconventional methods, an important role is
expected to be played by natural gases which are C.sub.1 compounds per se,
and other C.sub.1 compounds such as a synthesis gas (a mixture of carbon
monoxide and hydrogen), and carbon dioxide produced by gasification of
asphalt and solid fossil fuels such as coal, as well as methanol derived
from these gases. Utilization of these C.sub.1 compounds is one of the
top-priority objects that must be achieved as soon as possible to meet the
demand for less dependency on petroleum and use of more varigated sources
of ethylene and propylene derivatives.
Ethanol is known as an industrial chemical and basically it has been
manufactured by fermentation of natural products such as molasses or by
hydration of ethylene in the presence of an acid catalyst such as
phosphoric acid. As already mentioned, ethylene is one of the
petrochemicals which are getting more and more expensive. Coal and natural
gas are two ample natural resources, and both of them can be converted to
a synthesis gas (CO+H.sub.2) from which methanol can be produced. The
methanol further reacts with carbon monoxide and hydrogen under
appropriate conditions to form ethanol, acetaldehyde, dimethyl acetal and
methyl acetate [see, for example, Japanese Patent Publications Nos.
15692/66, 2525/73, Japanese Patent Public Disclosures Nos. 149213/76,
136110/77, 136111/77, 133914/76, Bull, Chem. Soc., Jpn., 52 (2), 479-482
(1979)].
Like ethanol, vinyl acetate is a well known industrial chemical. It is one
of the oldest vinyl monomers and polyvinyl acetate and PVA (polyvinyl
alcohol) are useful synthetic polymers, so there are many different
methods to produce it on an industrial scale. In old days, vinyl acetate
was typically synthesized from acetylene, and these days, the acetylene
process is being displaced by a more advantageous ethylene process. The
first concept of direct synthesis of vinyl acetate from ethylene used a
palladium chloride catalyst or sodium acetate in the reaction system.
Alternative methods were proposed wherein vinyl acetate and acetic acid
were produced from acetaldehyde and acetic anhydride either directly or
through ethylidene diacetate (1,1-diacetoxyethane) [see, for example,
Hydrocarbon Process, 44 (11) 287 (1965), British Pat. No. 1,112,555, U.S.
Pat. Nos. 2,021,698, 2,425,389 and 2,860,159]. In these methods,
acetaldehyde and acetic anhydride are reacted directly to form vinyl
acetate and acetic acid or they first react to form ethylidene diacetate
which is then thermally decomposed to vinyl acetate and acetic acid.
Acetic anhydride used as one of the two starting materials in these methods
has been commercially produced by the Wacker process wherein acetone or
acetic acid is thermally decomposed to ketene which is then reacted with
acetic acid to produce acetic anhydride. Methods have been proposed
recently that produce acetic anhydride directly from methyl acetate and
carbon monoxide by reacting them in the presence of a carbonylation
catalyst and a halide (see, for example, Japanese Patent Publication No.
3926/77, Japanese Patent Public Disclosures Nos. 65709/76 and 59214/79).
Acetaldehyde, the other material for the production of vinyl acetate by
thermal decomposition is an industrial chemical that is commercially
produced mainly by direct oxidation of ethylene or light hydrocarbons. In
other words, like ethanol, vinyl acetate or acetic anhydride, acetaldehyde
is also supplied to the market as a product produced from petrochemicals
whose prices keeps going up. Methods have therefore been proposed to
produce C.sub.2 compounds directly from a synthesis gas (see, for example,
Japanese Patent Public Disclosures Nos. 80806/76 and 80807/76). These
methods constitute an attractive process for synthesizing C.sub.2
compounds, considering only the starting material. But unfortunately, the
process involves a gas-phase reaction using a solid catalyst one component
of which is rhodium, so metallic rhodium in the solid catalyst changes to
volatile rhodium carbonyl which escapes out of the reaction system until
the catalytic activity is lost. This defect is fatal to the process if it
is to be performed on an industrial scale, and a considerable time will be
necessary to eliminate such defect.
According to more viable methods, C.sub.2 compounds such as acetaldehyde
and ethanol are produced from methanol and synthesis gas, as taught in,
say, Japanese Patent No. 2525/73, Japanese Patent Public Disclosures Nos.
149213/76, 136110/77, 136111/77, and Bull, Chem. Soc. Jpn., 52 (2),
479-482 (1979). The reactions that occur in these methods for producing
ethanol, acetaldehyde, methyl acetate and dimethyl acetal are
schematically represented by the following formulae:
(1) CH.sub.3 OH+CO+2H.sub.2 .fwdarw.CH.sub.3 CH.sub.2 OH+H.sub.2 O
(2) CH.sub.3 OH+CO+H.sub.2 .fwdarw.CH.sub.3 CHO+H.sub.2 O
(3) 2CH.sub.3 OH+CO.fwdarw.CH.sub.3 COOCH.sub.3 +H.sub.2 O
(4) 3CH.sub.3 OH+CO+H.sub.2 .fwdarw.CH.sub.3 CH(OCH.sub.3).sub.2 +2H.sub.2
O
As understood from these reaction formulae, the conventional methods for
producing ethanol and acetaldehyde by hydrocarbonylation of methanol is
disadvantageous in that it produces a great amount of methyl acetate or
dimethyl acetal other than the desired products. Attempts have been made
to improve the catalyst or increase the yield of ethanol and acetaldehyde
by recycling the by-products, but none of them have proved completely
satisfactory for practical purposes.
SUMMARY OF THE INVENTION
Therefore, one object of this invention is to achieve effective use of
ethanol and acetaldehyde produced from methanol and synthesis gas, as well
as methyl acetate and dimethylacetal by integrating them in an industrial
process as starting materials.
Another object of this invention is to produce vinyl acetate from materials
that are not derived from ethylene or other petrochemicals.
These objects of this invention are achieved by integrating the step of
hydrocarbonylation and, the steps for producing acetic anhydride and vinyl
acetate into a systematic process.
Therefore, in step (a) of the process of this invention, methanol is
hydrocarbonylated to C.sub.2 compounds such as ethanol, acetaldehyde,
methyl acetate and dimethylacetal, and the reaction mixture containing
these compounds is then freed of ethanol, acetaldehyde, methyl acetate and
dimethylacetal; concurrently, in step (b), methyl acetate is carbonylated
to acetic anhydride which is then freed from the reaction mixture; the
mixture of acetaldehyde and dimethylacetal separated in step (a) is
reacted with acetic anhydride to form a vinyl acetate precursor ethylidene
diacetate (hereunder referred to as ED) and methyl acetate (step (c)), or
vinyl acetate, acetic acid and methyl acetate are produced directly and
simultaneously (step (c) combined with step (d)); both the methyl acetate
produced in the step (c) or the combination of steps (c) and (d) and the
methyl acetate produced in the step (a) are carbonylated to acetic
anhydride. The above cycle is repeated. When ED is synthesized as a
precursor, it is thermally decomposed (step (d)) to vinyl acetate and
acetic acid. In summary, this invention accomplishes simultaneous
production of vinyl acetate, acetic acid and ethanol from methanol, carbon
monoxide and hydrogen.
This invention provides a complex, recycling process for producing vinyl
acetate from methanol, carbon monoxide and hydrogen which comprises the
following five steps:
(a) methanol is hydrocarbonylated in a hydrocarbonylation zone to produce
ethanol, acetaldehyde, methyl acetate and dimethylacetal, and the products
are separated in a separation zone;
(b) methylacetate is carbonylated in a carbonylation zone to produce acetic
anhydride;
(c) the acetaldehyde and dimethylacetal produced in the step (a) and the
acetic anhydride produced in the step (b) are converted to ethylidene
diacetate and methyl acetate;
(d) the ethylidene diacetate produced in the step (c) is thermally
decomposed to vinyl acetate and acetic acid, and the products are
separated in a separation zone; and
(e) the methyl acetate produced and separated in the steps (a), (c) or (d)
is supplied to the carbonylation step (b).
BRIEF DESCRIPTION OF THE DRAWING:
FIG. 1 is a flow sheet illustrating an embodiment of the process of this
invention.
DETAILED DESCRIPTION OF THE INVENTION:
The respective steps of this invention are hereunder described in detail.
Step (a):
Hydrocarbonylation of methanol with carbon monoxide and hydrogen is
preferably performed in the hydrocarbonylation zone in the presence of a
catalyst, say, a metal belonging to the group VIII of the periodic table,
such as cobalt or ruthenium described in Japanese Patent Publications Nos.
15692/66, 2525/73, Japanese Patent Public Disclosures Nos. 149213/76,
136110/77, 136111/77, 133914/76, and Bull. Chem. Soc. Jpn., 52 (2),
479-482 (1979). A cobalt catalyst is particularly preferred. The metal
catalyst used in this invention may be in any valence state having a
desired atomic valency including zero. Illustrative cobalt metal catalysts
include metallic cobalt, cobalt acetylacetonate, cobalt hydroxide, cobalt
carbonate, cobalt formate, cobalt acetate, cobalt propionate, cobalt
naphthenate, cobalt stearate, cobalt chloride, cobalt bromide, cobalt
iodide, dicobalt octacarbonyl, tetracobalt dodecacarbonyl,
hydridotetracarbonylcobalt, and dicobalt hexacarbonyl
bis(tri-n-butylphosphine). The amount of the metal catalyst used is not
critical, but usually, 10.sup.-6 to 0.5 mols, preferably 10.sup.-5 to 0.05
mols, more preferably from 10.sup.-4 to 0.025 mols, of the metal catalyst
is used per liter of the reaction medium on the basis of metal atom.
The hydrocarbonylation may be carried out with advantage using a halogen or
a halide as a secondary component. Preferred halides are bromides or
iodides or mixtures thereof. Illustrative halides are alkyl halides such
as methyl iodide, acid halogenides such as acetyl iodide, hydrogen halides
such as hydrogen iodide, and organic halide salts and inorganic halides
such as ammonium iodide and tetramethyl ammonium iodide salt. Iodines
(I.sub.2), bromine (Br.sub.2) and inorganic halides such as alkali metal
and alkaline earth metal halides are particularly preferred. Iodine
(I.sub.2) and bromine (Br.sub.2) are also effective and they immediately
react with the reactants to form an iodide or bromide. Typical examples of
these inorganic halides are LiI, KI, NaI, CaI.sub.2, HIO.sub.3, LiBr, KBr,
NaBr, CaBr.sub.2, and HBrO.sub.3. These halogen or halides are added to
the reaction system in an amount of from 10.sup.-6 to 0.25 mols,
preferably from 10.sup.-5 to 0.05 mols per liter of the reaction medium on
the basis of halogen atom.
The hydrocarbonylation reaction of this invention may be adequately
achieved in the presence of a catalyst system consisting of a
carbonylation catalyst and a halide secondary component, but an organic
reaction accelerator may be used in combination with the catalyst system.
Advantageous organic reaction accelerators are organic nitrogen,
phosphorus, antimony, arsenic and bismuth compounds. Part of these
compounds are represented by the following formula:
##STR1##
(wherein M is N, P, Sb, As or Bi; R.sub.1, R.sub.2 and R.sub.3 which may
be the same or different are each hydrogen, or an alkyl, cycloalkyl or
aryl group preferably having not more than 10 carbon atoms). The following
are examples of the organic reaction accelerator which are given here not
for limiting purposes but for illustrative purposes only: amines such as
monomethylamine, dimethylamine, trimethylamine, dimethylethylamine,
diethylamine, tri-iso-propylamine, tri-n-propylamine, tri-n-butylamine,
tri-tert-butylamine, aniline, dimethylaniline, and diethylaniline;
phosphines such as tri-n-propylphosphine, tri-iso-propylphosphine,
tri-n-butylphosphine, tri-tert-butylphosphine, tricyclohexylphosphine,
ethylene bis(diphenylphosphine) and triphenylphosphine; arsines such as
trimethylarsine, triethylarsine, tricyclohexylarsine, triphenylarsine,
phenyl-di-iso-propylarsine, diphenylarsine, bis(diphenylarsino) ethane,
and bis(di-iso-propylarsino)hexane; stibines such as
tri-iso-propylstibine, ethyl-di-iso-propylstibine, triphenylstibine,
tri(o-tolyl)-stibine, phenyldiamylstibine, tris(diethylaminomethyl)stibine
and bis(diethylstibino)pentane; and triphenylbismuth, trimethylbismuth,
tricyclohexylbismuth and triethylbismuth.
Other organic nitrogen compounds which may or may not contain oxygen or
phosphorus atom are used with advantage as the organic reaction
accelerator. Non-limiting examples of these compounds include heterocyclic
compounds such as pyrrole, pyrrolidine, piperidine, pyrimidine, picolines,
pyrazine and N-C.sub.1-5 lower alkyl substituted derivatives thereof such
as N-methylpyrrolidine, benzotriazole, piperazine, N-methyl piperazine,
N-ethylpiperazine, 2-methyl-N-methylpiperazine, 2,2-dipyridyl,
methyl-substituted 2,2-dipyridyl, 1,4-diazabicyclo(2,2,2)octane,
methyl-substituted 1,4-diazabicyclo(2,2,2)octane, purine, 2-aminopyridine,
1,10-phenanthroline, methyl-substituted 1,10-phenanthroline,
2-(dimethylamino)pyridine, 2-(dimethylamino)-6-methoxyquinoline,
7-chloro-1,10-phenanthroline, 4-triethylsilyl-2,2'-dipyridyl,
5-(thiabenzyl)-1,10-phenanthroline, pyridine, 2,4-dimethyl pyridine,
2,6-dimethyl pyridine, 2,4,6-trimethylpyridine, and imidazole; diamines,
such as N,N,N',N'-tetramethylethylenediamine,
N,N,N',N'-tetraethylethylenediamine,
N,N,N',N'-tetra-n-propylethylenediamine,
N,N,N',N'-tetramethylmethylenediamine,
N,N,N',N'-tetraethylethylenediamine, and
N,N,N',N'-tetra-iso-butylmethylenediamine; and nitriles, such as
acetonitrile, propionitrile, adiponitrile, and benzonitrile.
The organic compounds having oxygen or phosphorus atom and nitrogen atom
include hydroxyl or carboxyl-substituted compounds of the above mentioned
organic nitrogen compounds, such as 2-hydroxypyridine, methyl-substituted
2-hydroxypyridine, picolinic acid, methyl-substituted picolinic acid,
2,5-dicarboxypiperazine, ethylenediaminetetraacetic acid,
2,6-dicarboxypyridine, 8-hydroxyquinoline, 2-carboxyquinoline,
cyclohexane-1,2-diamine-N,N,N',N'-tetraacetic acid, salts of
ethylenediaminetetraacetic acid, such as tetramethyl ester of
ethylenediaminetetraacetic acid, ammonium salts like ammonium acetate;
carboxylic amides, such as acetamide, acetanilide, N,N-dimethylacetamide,
and N-methyl-N-phenylacetamide; amino acids, such as N,N-dimethylglycine,
and N,N-diethylglycine; 1-methyl-2-pyrrolidinone, 4-methyl-morpholine,
N,N,N',N'-tetramethylurea, N-methyliminodiacetic acid, nitrilotriacetic
acid, and N-methyl iminodiacetic acid; and phosphine iminium salts such as
triphenylphosphine iminium chloride. Organic reaction accelerators having
trivalent nitrogen, phosphorus, antimony and bismuth are particularly
preferred.
The amount of the organic reaction accelerator used depends on the amount
of the metal catalyst used in the reaction zone, but usually, 10.sup.-6 to
0.25 mols, preferably 10.sup.-5 to 0.05 mols of the accelerator per liter
of the reaction medium is used.
In the practice of this invention, hydrocarbonylation is performed suitably
at a temperature in the range of from 50.degree. to 450.degree. C.,
preferably from 100.degree. to 350.degree. C., and more preferably from
150.degree. to 300.degree. C. Carbon monoxide and hydrogen preferably have
a partial pressure of from 15 to 1000 atm., more preferably from 20 to 800
atm., and most preferably from 25 to 400 atm. A partial pressure may be in
the range of from 10 to 1500 atm. Carbon monoxide and hydrogen may be
supplied under pressure to the reaction zone either independently or as a
mixture. The molar ratio of carbon monoxide to hydrogen is selected from a
wide range of 1:100 to 100:1, but a preferred range is from 1:50 to 50:1,
and a more preferred range is from 1:10 to 10:1. Good results are obtained
when a gas mixture having a CO to H.sub.2 ratio close to the stoichio
metrical ratio of the two gases used for synthesis of C.sub.2 compounds is
used, and for this purpose, using a CO to H.sub.2 molar ratio between 1:5
and 5:1 is a particularly preferred operation method. Carbon monoxide and
hydrogen need not always have high purity and they may contain carbon
dioxide, methane, nitrogen, rare gas, water or a trace amount of oxygen.
Carbon monoxide and hydrogen of extremely low purity are not preferred
because they increase the pressure of the reaction system.
Usually, the effluent from the hydrocarbonylation zone is a mixture of gas
and liquid and directed to a high-pressure separation unit for gas-liquid
separation. Most of the gas separated is recycled to the reaction zone.
The liquid effluent is freed of ethanol/acetaldehyde and methyl
acetate/dimethylacetal by a suitable separation technique such as
distillation or liquid-liquid separation, and the unreacted methanol,
halide component and metallic catalyst component are recovered and
recycled to the hydrocarbonylation zone. Likewise, part of the products
such as dimethylacetal and methyl acetate may be recycled to the
hydrocarbonylation zone. The separation zone usually consists of more than
one distillation unit such as a flash distillation column and/or
separation column. The distillation unit is typically used at a
temperature between 40.degree. and 200.degree. C. and a pressure less than
5 atm. The liquid-liquid separation zone usually consists of more than one
liquid-liquid separation unit such as extraction column and/or
liquid-liquid separation column. The liquid-liquid separation zone is
operated by a method well known to those skilled in the art and is
primarily used for separation of methanol and dimethylacetal.
Most of methyl acetate produced in the step (a) is usually supplied as the
material for the step (b). Dimethylacetal on the other hand is used as a
material for the step (c) after it is separated from methanol and other
contaminating substances in the effluent by such a technique as
distillation or liquid-liquid separation. Alternatively, the
dimethylacetal is hydrolyzed by a known method to methanol and
acetaldehyde which is supplied as a material for the step (c). Otherwise,
the dimethylacetal may be recycled to the step (a) together with the
unreacted methanol. In a desired embodiment, the recently proposed method
of producing C.sub.2 compounds such as acetaldehyde and ethanol directly
from a synthesis gas (see, for example, Japanese Patent Public Disclosures
Nos. 80806/76 and 80807/76) may be applied to the hydrocarbonylation zone
of the step (a).
Step (b):
In the step (b), acetic anhydride may be produced from the carbonylation
zone as a result of carbonylation of methyl acetate with carbon monoxide.
The reaction is performed with advantage in the presence of a catalyst. A
suitable catalyst is composed of a metal component and halide component,
that produces a carbonyl compound in the reaction system (illustrative
catalysts are described in, say, Japanese Patent Publication No. 3926/77,
Japanese Patent Public Disclosures Nos. 65709/76 and 59214/79). The metal
component is based on the use of a metal of group VIII, and a component
based on palladium, iridium, rhodium, nickel or cobalt is effective, and
one based on palladium, rhodium or nickel is particularly effective. The
metal component is used in any suitable form, and some of their examples
include: RhX.sub.3, RhX.sub.3.3H.sub.2 O, [RhX(CO).sub.2 ].sub.2, Rh.sub.6
(CO).sub.16, RhX(PPh.sub.3).sub.3, Rh(SnCl.sub.3) (PPh.sub.3).sub.3,
RhI(CO)(SbPh.sub.3).sub.2, RhH(CO)(PPh.sub.3).sub.3, Rh(AcAc).sub.3,
Rh(OAc)(PPh.sub.3).sub.2, metallic Rh, Rh.sub.2 (CO).sub.3,
RhX(CO)(PPh.sub.3).sub.2, RhCl(CO)(AsPh.sub.3).sub.2, RhX(CO)
[P(n--C.sub.4 H.sub.9).sub.3 ].sub.2, [Rh(C.sub.2 H.sub.4).sub.2
Cl].sub.2, [Rh(AcO).sub.2 ].sub.2, RhCl(CO)[P(OPh).sub.3 ].sub.2,
[Rh{P(OPh).sub.3 }.sub.4 ].sub.2, RhCl(Ph.sub.3 P).sub.2 (CH.sub.3
I).sub.2, [Rh(CO).sub.2 X][(n--C.sub.4 H.sub.9).sub.4 N], [Rh.sub.2
O.sub.2 X.sub.4 ] [(n--C.sub.4 H.sub.9).sub.4 As].sub.2, [Rh(CO)I.sub.4
][(n--C.sub.4 H.sub.9).sub.4 P], PdX.sub.2, [Pd(CO)X.sub.2 ].sub.2,
[Pd(PPh.sub.3).sub.2 ].sub.2, [Pd(PPh.sub.3)].sub.2 (CO)Br, [PdX.sub.4
][(n--C.sub.4 H.sub.9).sub.4 P], Pd[(n--C.sub.4 H.sub.9).sub.3
P](CO)Cl.sub.2, PdCl(PPh.sub.3).sub.2 (SnCl).sub.3, Pd[(n--C.sub.4
H.sub.9).sub.3 P].sub.2 I.sub.2, NiX.sub.2, NiX.sub.2.3H.sub.2 O,
Ni(CO).sub.4, Ni(CO).sub.2 (PPh.sub.3).sub.2, Ni(AcAc).sub.2, metallic Ni
and Ni(OAc).sub.2 (wherein X is Cl, Br or I; Ph is phenyl; OPh is phenoxy;
Ac is acetyl; OAc is acetoxy; and AcAc is acetylacetonate).
The amount of these metal catalyst used is not critical, but generally, it
is from 10.sup.-6 to 5 mols, preferably from 10.sup.-4 to 4 mols, more
preferably from 10.sup.-3 to 2 mols, per liter of the reaction medium.
The carbonylation requires the presence of not only a metal catalyst but
also a halide, and an advantageous halide is a bromide or iodide or a
mixture thereof, and an iodide is preferred. The halide is generally
present in the reaction medium in the form of methyl halide, acetyl
halide, hydrogen halide or any mixture thereof, so it may be supplied to
the reaction medium as such or a compound that forms at least one of
halide, methyl halide, acetyl halide or hydrogen halide in the reaction
medium may be supplied to the medium. The compound that reacts with other
components in the reaction medium to form methyl halide, acetyl halide
and/or hydrogen halide is inorganic halides such as alkali metal halides
and alkaline earth metal halides, as well as elemental iodine and bromine.
The amount of these halides used is also not critical, but usually
10.sup.-6 to 20 mols, preferably from 10.sup.-4 to 10 mols, of halide per
liter of the reaction medium interms of halogen atm is used.
As described above, the carbonylation may be performed with advantage in
the presence of a catalyst system composed of a metal catalyst and halide
secondary component, but it is further enhanced by using an organic or
inorganic accelerator. An organic accelerator is particularly effective.
The organic accelerator can be supplied to the reaction zone
simultaneously with the reactants, or a metal coordination complex
resulting from the separate mixing of the accelerator and catalyst metal
may be supplied to the reaction zone.
Advantageous organic accelerators are organic nitrogen, phosphorus,
antimony and arsenic compounds. Part of these compounds are represented by
the following formula:
##STR2##
(wherein M is N, P, Sb or As; R.sub.1, R.sub.2 and R.sub.3 which may be
the same or different and each represents hydrogen or alkyl, cycloalkyl or
aryl preferably having 10 carbon atoms or less). The following are
examples of the organic reaction accelerator which are given here not for
limiting purposes but for illustrative purposes only: amines such as
monomethylamine, dimethylamine, trimethylamine, dimethylethylamine,
diethylamine, tri-iso-propylamine, tri-n-propylamine, tri-n-butylamine,
tri-tert-butylamine, aniline, dimethylaniline, and diethylaniline;
phosphines such as tri-n-propylphosphine, tri-iso-propylphosphine,
tri-n-butylphosphine, tri-tert-butylphosphine, tricyclo-hexylphosphine,
ethylene bis(diphenylphosphine) and triphenyl-phosphine; arsines such as
trimethylarsine, triethylarsine, tricyclohexylarsine, triphenylarsine,
phenyl-di-iso-propylarsine, diphenylarsine, bis(diphenylarsino)ethane, and
bis(di-iso-propylarsino)hexane; stibines such as tri-iso-propylstibine,
ethyl-di-iso-propyl-stibine, triphenylstibine, tri(o-tolyl)-stibine,
phenyldiamylstibine, tris(diethylaminomethyl)stibine and
bis(diethylstibino)pentane.
Other organic nitrogen compounds which may or may not contain oxygen or
phosphorus atom are used with advantage as the organic reaction
accelerator. Non-limiting examples of these compounds include heterocyclic
compounds such as pyrrole, pyrrolidine, piperidine, pyrimidine, picolines,
pyrazine and N-C.sub.1-5 lower alkyl substituted derivatives thereof such
as N-methylpyrrolidine, benzotriazole, piperazine, N-methyl piperazine,
N-ethylpiperazine, 2-methyl-N-methylpiperazine, 2,2-dipyridyl,
methyl-substituted 2,2-dipyridyl, 1,4-diazabicyclo(2,2,2)octane,
methyl-substituted 1,4-diazabicyclo(2,2,2)octane, purine,
2-amino-pyridine, 1,10-phenanthroline, methyl-substituted
1,10-phenanthroline, 2-(dimethylamino)-pyridine,
2-(dimethylamino)-6-methoxyquinoline, 7-chloro-1,10-phenanthroline,
4-triethylsilyl-2,2'-dipyridyl, 5-(thiabenzyl)-1,10-phenanthroline,
pyridine, 2,4-dimethyl pyridine, 2,6-dimethyl pyridine,
2,4,6-trimethylpyridine, and imidazole; diamines, such as
N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine,
N,N,N',N'-tetra-n-propylethylenediamine,
N,N,N',N'-tetramethylemethylenediamine,
N,N,N',N'-tetraethylethylenediamine, and
N,N,N',N'-tetra-iso-butylmethylenediamine; and nitrilies, such as
acetonitrile, propionitrile, adiponitrile, and benzonitrile.
The organic compounds having oxygen or phosphorus atom and nitrogen atom
include hydroxyl or carboxyl-substituted compounds of the above mentioned
organic nitrogen compounds, such as 2-hydroxypyridine, methyl-substituted
2-hydroxypyridine, picolinic acid, methyl-substituted picolinic acid,
2,5-dicarboxypiperazine, ethylenediaminetetraacetic acid,
2,6-dicarboxypyridine, 8-hydroxyquinoline, 2-carboxyquinoline,
cyclohexane-1,2-diamine-N,N,N',N'-tetraacetic acid, salts of
ethylenediaminetetraacetic acid, such as tetramethyl ester of
ethylenediaminetetraacetic acid, ammonium salts like ammonium acetate;
carboxylic amides, such as acetamide, acetanilide, N,N-dimethylacetamide,
and N-methyl-N-phenylacetamide; amino acids, such as N,N-dimethylglycine,
and N,N-diethylglycine; 1-methyl-2-pyrrolidinone, 4-methylmorpholine,
N,N,N',N'-tetramethylurea, N-methyliminodiacetic aicd, nitrilotriacetic
acid, and N-methyl iminodiacetic acid; and phosphine iminium salts such as
triphenylphosphine iminium chloride. Organic reaction accelerators having
trivalent nitrogen and phosphrus are particularly preferred.
Effective inorganic accelerators include metals having atomic weight of at
least 6 and belonging to Groups Ia, IIa, IIIa, IVa, Ib, IIb, Vb, VIb and
VIIb of the Periodic Table and compounds of these metals. Metals of these
groups having atomic weight of less than 120 are preferred. Lithium,
sodium, potassium, magnesium, calcium, aluminum, tin, zinc, cadmium,
copper, manganese, chromium, and vanadium are preferred. The inorganic
accelerator may be used in a finely divided elemental form, or it may be
used in various inorganic or organic compounds effective for introducing
an element into the reaction system in a cationic form under reaction
conditions. Therefore, typical compound of element as inorganic
accelerator include oxides, hydroxides, halides preferably bromide and
iodide, oxyhalides, hydrides, carbonyls, alkoxides, nitrates, nitrides,
phosphates, and aliphatic, alicyclic, naphthenic and aryl-aliphatic
monocarboxylates such as acetate, butyrate, decanoate, laurate, stearate
and benzoate. Other advantageous compounds are metal alkyls, chelates,
associate compounds and enol salts. Particularly advantageous inorganic
accelerators are bromides, iodides and organic acid salts preferably
acetates. If desired, the catalytic metal may be combined to advantage
with organic and inorganic accelerators. The amount of the organic or
inorganic accelerator depends on the amount of the catalytic metal in the
reaction zone, and generally 10.sup.-6 to 10 mols, preferably from
10.sup.-4 to 5 mols, per liter of the reaction medium is used.
The carbonylation for performing the process of this invention may be
suitably carried out at a temperature between 40.degree. and 450.degree.
C., preferably between 80.degree. C. and 300.degree. C., more preferably
between 100.degree. and 250.degree. C. Carbon monoxide preferably has a
partial pressure between 0.5 and 350 atm., more preferably between 1 and
300 atm., and most preferably between 3 and 250 atm. A partial pressure
may be in the range of from 0.05 to 100 atm. Carbon monoxide need not
always have high purity and it may contain hydrogen, carbon dioxide,
methane, nitrogen, or rare gas. Carbon monoxide of extremely low purity is
not preferred because it increases the pressure of the reaction system.
The effluent from the carbonylation zone is freed of acetic anhydride by a
suitable separation technique such as distillation, and the unreacted
methyl acetate, iodine and metal catalytic component are recovered and
recycled to the carbonylation zone. The separation zone usually consists
of more than one distillation unit, such as flash distillation column
and/or separation column. The distillation unit is typically used at a
temperature between 40.degree. and 200.degree. C. and a pressure less than
5 atm. Part or all of the unreacted waste gas from the step (b) can be
used as supply gases for the step (a). Such recycling of supply gases and
unreacted waste gas constitute an effective embodiment.
Step (c):
In the step (c), ED (ethylidene diacetate) and methyl acetate are formed in
the ED synthesis zone through the reaction between acetaldehyde and/or
dimethylacetal and acetic anhydride. The conversion to ED does not
necessarily require a catalyst, but it is performed with advantage in the
presence of an acid catalyst (as described in U.S. Pat. No. 2,021,698 and
Japanese Patent Application No. 117659/79 filed by the present applicant).
The following are examples of the acid catalyst for use in this invention
which are given here not for limiting purposes but for illustrative
purposes only: Bronsted acids such as HI, HBr, HCl, HF, H.sub.2 SO.sub.4,
HNO.sub.3, H.sub.3 PO.sub.4, H.sub.3 BO.sub.3, HClO.sub.3, HBrO.sub.3,
HIO.sub.3, polyphosphoric acid, benzenesulfonic acid, and
alkylbenzenesulfonic acid; Lewis acids of halides having a central atom of
Groups IIa, IIIa, IVa, Va, VIa, IIIb, IVb, Vb, VIb, VIIb and VIII of the
periodic table, such as PbX.sub.2, MgX.sub.2, BX.sub.3, B.sub.2 X.sub.4,
AlX.sub.3, GaX.sub.2, GaX.sub.3, InX, InX.sub.2, InX.sub.3, TlX,
TlX.sub.3, TlX.sub.4, SiX.sub.4, Si.sub.2 X.sub.6, Si.sub.3 X.sub.8,
Si.sub.4 X.sub.10, Si.sub.5 X.sub.12, GeX, GeX.sub.2, GeX.sub.4,
SnX.sub.2, SnX.sub.4, PX.sub.3, PX.sub.5, P.sub.2 X.sub.4, AsX.sub.3,
AsX.sub.5, SbX.sub.3, SbX.sub.5, BiX, BiX.sub.2, BiX.sub.3, TiX.sub.2,
TiX.sub.3, TiX.sub.4, ZrX.sub.2, ZrX.sub.3, ZrX.sub.4, VX.sub.2, VX.sub.3,
VX.sub.4, CrX.sub.2, CrX.sub.3, MoX.sub.2, MoX.sub.3, MoX.sub.4,
MoX.sub.5, WX.sub.2, WX.sub.4, WX.sub.5, WX.sub.6, MnX.sub.2, MnX.sub.3,
MnX.sub.4, ReX.sub.3, ReX.sub.4, ReX.sub.6, FeX.sub. 2, FeX.sub.3,
CoX.sub.2, CoX.sub.3, CoX.sub.4, NiX.sub.2, RuX, RuX.sub.2, RuX.sub.3,
RuX.sub.4, CuX, CuX.sub.2, AuX, AuX.sub.2, AuX.sub.3, ZnX.sub.2,
CdX.sub.2, Hg.sub.2 X.sub.2, HgX.sub.2 (wherein X is F, Cl, Br or I).
Particularly preferred are MgCl.sub.2, MgBr.sub.2, MgI.sub.2, BF.sub.3,
BCl.sub.3, BI.sub.3, AlCl.sub.3, AlBr.sub.3, AlI.sub.3, SiCl.sub.4,
GeCl.sub.4, SnCl.sub.4, SnBr.sub.4, SnI.sub.4, SbCl.sub.5, SbBr.sub.3,
SbCl.sub.3, TiCl.sub.4, TiBr.sub.4, TiI.sub.4, CrCl.sub.3, CrBr.sub.3,
MoCl.sub.5, WCl.sub.6, FeCl.sub.3, FeBr.sub.3, FeI.sub.3, CoCl.sub.2,
CoBr.sub.2, NiCl.sub.2, NiBr.sub.2, NiI.sub.2, CuCl, CrBr, CuCl.sub.2,
CuI, ZnCl.sub.2, ZnBr.sub.2 and ZnI.sub.2 Lewis acids such as
B(CH.sub.3).sub.3 and SO.sub.3 are also used with advantage as the
catalyst.
Besides these homogeneous catalysts, solid acids can also be used to
facilitate the separation from the reaction products and prevent the
corrosion of the reactor. Examples of the effective solid catalyst include
clays such as kaolinite, bentonite, attapulgite, montmorillonite, clarite,
Fuller's earth and zeolites; solidified acids wherein H.sub.2 SO.sub.4,
H.sub.3 PO.sub.4 and H.sub.3 BO.sub.3 are attached to silica, quartz sand,
alumina and diatomaceous earth; cation exchange resins; charcoal
heattreated at a temperature near 300.degree. C.; solid inorganic
compounds such as ZnO, Al.sub.2 O.sub.3, ThO.sub.2, TiO.sub.2, ZrO.sub.2,
CeO.sub.2, As.sub.2 O.sub.3, V.sub.2 O.sub.3, Bi.sub.2 O.sub.3, SiO.sub.2,
Cr.sub.2 O.sub.3, MoO.sub.2, ZnS, CaS, CaSO.sub.4, MnSO.sub.4, NiSO.sub.4,
CuSO.sub.4, CoSO.sub.4, CdSO.sub.4, SrSO.sub.4, ZnSO.sub.4, MgSO.sub.4,
FeSO.sub.4, BaSO.sub.4, KHSO.sub.4, K.sub.2 SO.sub.4, Al.sub.2
(SO.sub.4).sub.3, Fe.sub.2 (SO.sub.4).sub.3, Cr.sub.2 (SO.sub.4).sub.3,
Ca(NO.sub.3).sub.2, Ni(NO.sub.3).sub.2, Fe(NO.sub.3).sub.3, BPO.sub.4,
FePO.sub.4, CrPO.sub.4, Ti.sub.3 (PO.sub.4).sub.4, Zr.sub.3
(PO.sub.4).sub.4, Cu.sub.3 (PO.sub.4).sub.2, Ni.sub.3 (PO.sub.4).sub.2,
AlPO.sub.4, Zn.sub.3 (PO.sub.4).sub.2, Mg(PO.sub.4).sub.2 ; solid
composite acid compounds such as SiO.sub.2 --Al.sub.2 O.sub.3, B.sub.2
O.sub.3 --Al.sub.2 O.sub.3, Cr.sub.2 O.sub.3 --Al.sub.2 O.sub.3, MoO.sub.2
--Al.sub.2 O.sub.3, MoO.sub.3 --SiO.sub.2, ArO.sub.2 --SiO.sub.2, Ga.sub.2
O.sub.3 --SiO.sub.2, BeO--SiO.sub.2, MgO--Sio.sub.2, Cao--SiO.sub.2,
SrO--SiO.sub.2, Y.sub. 2 O.sub.3 --SiO.sub.2, La.sub.2 O.sub.3
--SiO.sub.2, SnO--SiO.sub.2, PbO--SiO.sub.2, MoO.sub.3 --Fe.sub.2
(MoO.sub.4).sub.3, TiO.sub.2 --ZnO, TiO.sub.2 --ZrO.sub.2, TiO.sub.2
--SiO.sub.2, TiO.sub.2 --SnO.sub.2, TiO.sub.2 --WO.sub.3, TiO.sub.2
--MoO.sub.3, TiO.sub.2 --Sb.sub.2 O.sub.3, TiO.sub.2 --Fe.sub.2 O.sub.3,
TiO.sub.2 --Cr.sub.2 O.sub.3, TiO.sub.2 --V.sub.2 O.sub.3, TiO.sub.2
--Mn.sub.2 O.sub.3, TiO.sub.2 --Co.sub.3 O.sub.4, TiO.sub.2 --NiO,
TiO.sub.2 --CuO, TiO.sub.2 --Al.sub.2 O.sub.3, TiO.sub.2 --Bi.sub.2
O.sub.3, TiO.sub.2 --CdO, ZnO--Bi.sub.2 O.sub.3, ZnO--As.sub.2 O.sub.3,
ZnO--Al.sub.2 O.sub.3, ZnO--SiO.sub.2, ZnO--ZrO.sub.2, ZnO--Fe.sub.2
O.sub.3, ZrO.sub.2 --ThO.sub.2, Al.sub.2 O.sub.3 --NiO, Al.sub.2 O.sub.3
--NiO, Al.sub.2 O.sub.3 --Co.sub.3 O.sub.4, Al.sub.2 O.sub.3 --CdO,
Al.sub.2 O.sub.3 --Fe.sub.2 O.sub.3, Al.sub.2 O.sub.3 --Bi.sub.2 O.sub.3,
Al.sub.2 O.sub.3 --ZrO.sub.2, ZrO.sub.2 --CdO, TiO.sub.2 --MgO.
The homogeneous catalysts of Lewis acid type are used with particular
advantage at low temperatures.
The homogeneous acid catalyst is used in this in | | |
