U.S. patent application number 09/813394 was filed with the patent office on 2001-08-16 for catalyst composition and method for producing diaryl carbonates, using bisphosphines.
Invention is credited to Ofori, John Yaw, Patel, Ben Purushatom, Shalyaev, Kirill Vladimirovich, Soloveichik, Grigorii Lev.
Application Number | 20010014753 09/813394 |
Document ID | / |
Family ID | 23850168 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010014753 |
Kind Code |
A1 |
Soloveichik, Grigorii Lev ;
et al. |
August 16, 2001 |
Catalyst composition and method for producing diaryl carbonates,
using bisphosphines
Abstract
Hydroxyaromatic compounds such as phenol are carbonylated with
oxygen and carbon monoxide in the presence of a catalyst system
comprising a Group VIIIB metal, preferably palladium; at least one
bromide or chloride salt, preferably sodium bromide or a
tetraalkylammonium bromide; at least one organic bisphosphine such
as 1,3-bis(diphenylphosphino)propane or
1,4-bis(diphenylphosphino)butane; and a compound of a metal other
than a Group VIII metal having an atomic number of at least 44,
preferably a lead bromophenoxide. There may also be present a polar
organic liquid as a cosolvent.
Inventors: |
Soloveichik, Grigorii Lev;
(Latham, NY) ; Patel, Ben Purushatom; (Albany,
NY) ; Ofori, John Yaw; (Niskayuna, NY) ;
Shalyaev, Kirill Vladimirovich; (Clifton Park, NY) |
Correspondence
Address: |
GENERAL ELECTRIC COMPANY
CRD PATENT DOCKET ROOM 4A59
P O BOX 8
BUILDING K 1 SALAMONE
SCHENECTADY
NY
12301
US
|
Family ID: |
23850168 |
Appl. No.: |
09/813394 |
Filed: |
March 21, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09813394 |
Mar 21, 2001 |
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09466031 |
Dec 20, 1999 |
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6245929 |
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Current U.S.
Class: |
558/268 |
Current CPC
Class: |
C07C 69/96 20130101;
C07C 69/96 20130101; C07C 68/01 20200101; C07C 68/01 20200101; C07C
68/01 20200101 |
Class at
Publication: |
558/268 |
International
Class: |
C07C 069/96 |
Claims
What is claimed is:
1. A method for preparing a diaryl carbonate, said method
comprising the step of contacting at least one hydroxyaromatic
compound with oxygen and carbon monoxide in the presence of a
carbonylation catalyst system comprising a catalytic amount of at
least one organic bisphosphine.
2. The method of claim 1, wherein the carbonylation catalyst system
further comprises catalytic amounts of the following components and
any reaction products thereof: (A) a Group VIII metal having an
atomic number of at least 44 or a compound thereof, (B) at least
one bromide or chloride salt, and (C) at least one cocatalyst that
is a compound of a metal other than a Group VIII metal having an
atomic number of at least 44.
3. The method of claim 2, wherein component B is at least one
bromide salt.
4. The method of claim 1, wherein the organic bisphosphine has the
formula (R.sup.1).sub.2P-R.sup.2-P(R.sup.1).sub.2, (I) wherein each
R.sup.1 is independently a monovalent organic radical and R.sup.2
is a divalent organic radical.
5. The method of claim 4, wherein each R.sup.1 is an aromatic or
alicyclic radical.
6. The method of claim 5, wherein each R.sup.1 is phenyl.
7. The method of claim 4, wherein R.sup.2 is a C.sub.3-8 aliphatic
radical.
8. The method of claim 4, wherein the organic bisphosphine is
1,3-bis(diphenylphosphino)propane.
9. The method of claim 4, wherein the organic bisphosphine is
1,4-bis(diphenylphosphino)butane.
10. The method of claim 1, wherein the organic bisphosphine is
introduced into the catalytic material as a discrete compound.
11. The method of claim 2, wherein the organic bisphosphine is
introduced into the catalytic material as a preformed complex with
component A.
12. The method of claim 2, wherein the hydroxyaromatic compound is
phenol.
13. The method of claim 2, wherein the Group VIIIB metal in
component A is palladium.
14. The method of claim 13, wherein component A is palladium(II)
acetate or palladium(II) 2,4-pentanedionate.
15. The method of claim 2, wherein component C comprises lead(II)
oxide, a lead(II) aryloxide or lead(II) 2,4-pentanedionate.
16. The method of claim 2, wherein component C comprises a salt of
at least one of cerium, titanium, copper, zinc, manganese, bismuth
and europium.
17. The method of claim 2, wherein compound C comprises a lead
bromophenoxide.
18. The method of claim 2, wherein component B is an alkali metal
bromide.
19. The method of claim 18, wherein component B is sodium
bromide.
20. The method of claim 2, wherein component B is a
tetraalkylammonium bromide.
21. The method of claim 2, wherein there is also present (D) a
cosolvent which is a polar organic liquid.
22. The method of claim 21, wherein component D is an ether, amide,
sulfone or nitrile.
23. The method of claim 2, wherein a desiccant is also present.
24. The method of claim 21, wherein component A is present in the
amount of about 0.1-10,000 ppm by weight of said Group VIII metal
based on the total of hydroxyaromatic compound and the organic
bisphosphine; component B in the amount of about 1-2,000 mmol per
equivalent of the Group VIII metal of component A; the organic
bisphosphine in a ratio of moles to gram-atoms of the Group VIII
metal of component A in the range of about 1.0-1.2:1; component C
in the amount of about 0.2-200 gram-atoms of total metal per
equivalent of the Group VIII metal of component A; and component D,
when present in the amount of 1-60% by volume based on the total of
hydroxyaromatic compound and component D.
25. The method of claim 2, wherein the proportion of oxygen is
about 1-50 mole percent based on total oxygen and carbon
monoxide.
26. The method of claim 2, wherein a pressure in the range of about
1-500 atm and a temperature in the range of about 60-150.degree. C.
are maintained.
27. A method for preparing diphenyl carbonate which comprises
contacting phenol with oxygen and carbon monoxide in the presence
of an amount effective for carbonylation of at least one catalytic
material comprising the following and any reaction products
thereof: (A) palladium or a compound thereof, (B) at least one of
sodium bromide and a tetraalkylammonium bromide, (C) at least one
of 1,3-bis(diphenylphosphino- )propane and
1,4-bis(diphenylphosphino)butane and (D) at least one lead
bromophenoxide.
28. A catalyst composition comprising the following and any
reaction products thereof: (A) a Group VIII metal having an atomic
number of at least 44 or a compound thereof, (B) at least one
bromide or chloride salt, (C) at least one organic bisphosphine,
and (D) at least one cocatalyst that is a compound of a metal other
than a Group VIII metal having an atomic number of at least 44.
29. The composition of claim 28, wherein component B is at least
one bromide salt.
30. The composition of claim 29, wherein component C has the
formula (R.sup.1).sub.2P-R.sup.2-P(R.sup.1).sub.2, (I) wherein each
R.sup.1 is independently a monovalent organic radical and R.sup.2
is a divalent organic radical.
31. The composition of claim 30, wherein each R.sup.1 is an
aromatic or alicyclic radical.
32. The composition of claim 31, wherein each R.sup.1 is
phenyl.
33. The composition of claim 32, wherein R.sup.2 is a C.sub.3-8
aliphatic radical.
34. The composition of claim 28, wherein the Group VIIIB metal in
component A is palladium.
35. The composition of claim 34, wherein component A is
palladium(II) acetate or palladium(II) 2,4-pentanedionate.
36. The composition of claim 28, wherein component D comprises
lead(II) oxide, a lead(II) aryloxide or lead(II)
2,4-pentanedionate.
37. The composition of claim 28, wherein component D comprises a
salt of at least one of cerium, titanium, copper, zinc, manganese,
bismuth and europium.
38. The composition of claim 28, wherein compound D comprises a
lead bromophenoxide.
39. The composition of claim 28, wherein component B is sodium
bromide.
40. The composition of claim 39, wherein component B is a
tetraalkylammonium bromide.
41. The composition of claim 28, further comprising (E) a cosolvent
which is a polar organic liquid.
42. The composition of claim 41, wherein component E is an ether,
amide, sulfone or nitrile.
43. A catalyst composition comprising the following and any
reaction products thereof: (A) palladium or a compound thereof, (B)
at least one of sodium bromide and a tetraalkylammonium bromide,
(C) at least one of 1,3-bis(diphenylphosphino)propane and
1,4-bis(diphenylphosphino)butane and (D) at least one lead
bromophenoxide.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to the preparation of diaryl
carbonates by carbonylation. More particularly, it relates to the
improvement of diaryl carbonate yield in the carbonylation
reaction.
[0002] Diaryl carbonates are valuable intermediates for the
preparation of polycarbonates by transesterification with
bisphenols in the melt. This method of polycarbonate preparation
has environmental advantages over methods that employ phosgene, a
toxic gas, as a reagent and environmentally detrimental chlorinated
aliphatic hydrocarbons such as methylene chloride as solvents.
[0003] Various methods for the preparation of diaryl carbonates by
an oxidative carbonylation (hereinafter sometimes simply
"carbonylation" for brevity) reaction of hydroxyaromatic compounds
with carbon monoxide and oxygen have been disclosed. In general,
the carbonylation reaction requires a rather complex catalyst.
Reference is made, for example, to U.S. Pat. No. 4,187,242, in
which the catalyst is a heavy Group VIII metal; i.e., a Group VIII
metal having an atomic number of at least 44, said metals
consisting of ruthenium, rhodium, palladium, osmium, iridium and
platinum, or a complex thereof. Palladium catalysts have been found
particularly useful; they include complexes with phosphines such as
triphenylphosphine.
[0004] The production of carbonates may frequently be improved by
including a metal-based cocatalyst along with the heavy Group VIII
metal catalyst. Metal-based cocatalysts have been described broadly
in U.S. Pat. Nos. 4,187,242, 4,201,721 and 5,380,907. Lead
compounds as cocatalysts are particularly detailed in U.S. Pat. No.
5,498,789. Also preferred in general is the use of various halides,
as illustrated by tetra-n-butylammonium bromide. Compounds
characterized as inert solvents, such as toluene, diethyl ether,
diphenyl ether and acetonitrile, can also be present.
[0005] Many of the catalyst systems known in the art have
disadvantages such as low active catalyst lifetime, typically 2
hours or less, and low selectivity to the desired diaryl carbonate
as a result of formation of relatively high proportions of
by-products such as bromophenols.
[0006] Also, it has been observed that certain palladium-based
catalysts, such as palladium(II) acetate, show a decrease in
catalytic activity upon storage in contact with hydroxyaromatic
compounds such as phenol at temperatures on the order of 70.degree.
C. for periods as short as 2 hours. This decrease is notable
particularly when the palladium compound is present in catalyst
mixtures containing lead(II) oxide.
[0007] It is of interest, therefore, to develop catalyst systems
that have long lifetimes, not decreased by storage, and which
improve selectivity.
SUMMARY OF THE INVENTION
[0008] The present invention is based on the discovery that the
presence of bisphosphines in carbonylation catalyst systems,
whether added separately or as a preformed complex with the Group
VIII metal, affords a catalyst with good activity and relatively
long storage stability.
[0009] In one of its aspects, therefore, the invention is directed
to a method for preparing a diaryl carbonate. An embodiment of the
method comprises contacting at least one hydroxyaromatic compound
with oxygen and carbon monoxide in the presence of a catalytic
amount of a catalyst composition comprising at least one organic
bisphosphine and the following optional components and any reaction
products thereof: a Group VIII metal having an atomic number of at
least 44 or a compound thereof; at least one bromide or chloride
salt; and at least one cocatalyst which is a compound of a metal
other than a Group VIII metal having an atomic number of at least
44.
[0010] Another aspect of the invention is catalyst compositions
comprising the aforementioned components and any reaction products
thereof.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0011] Any hydroxyaromatic compound may be employed in the method
of the present invention. Monohydroxyaromatic compounds, such as
phenol, the cresols, the xylenols and p-cumylphenol, are generally
preferred with phenol being most preferred. The invention may,
however, also be employed with dihydroxyaromatic compounds such as
resorcinol, hydroquinone and 2,2-bis(4-hydroxyphenyl)propane or
"bisphenol A", whereupon the products are polycarbonate
oligomers.
[0012] Other reagents in the diaryl carbonate preparation method of
the invention are oxygen and carbon monoxide, which react with the
phenol to form the desired diaryl carbonate. They may be employed
in high purity form or diluted with another gas such as nitrogen,
argon or carbon dioxide, which has no negative effect on the
reaction.
[0013] For the sake of brevity, the constituents of the catalyst
system of the invention are defined as "components" irrespective of
whether a reaction between said constituents occurs before or
during the carbonylation reaction. Thus, the catalyst system may
include said components and any reaction products thereof.
[0014] Component A of the catalyst system is one of the heavy Group
VIII metals, preferably palladium, or a compound thereof. Thus,
useful palladium materials include elemental palladium-containing
entities such as palladium black, palladium/carbon,
palladium/alumina and palladium/silica; palladium compounds such as
palladium chloride, palladium bromide, palladium iodide, palladium
sulfate, palladium nitrate, palladium acetate and palladium
2,4-pentanedionate; and palladium-containing complexes involving
such compounds as carbon monoxide, amines, nitrites, phosphines and
olefins. Preferred in many instances are palladium(II) salts of
organic acids, most often C.sub.2-6 aliphatic carboxylic acids, and
palladium(II) salts of .beta.-diketones. Palladium(II) acetate and
palladium(II) 2,4-pentanedionate are generally most preferred.
Mixtures of the aforementioned palladium materials are also
contemplated.
[0015] Component B is at least one bromide or chloride salt. It may
be an alkali metal or alkaline earth metal halide, preferably a
bromide such as lithium bromide, sodium bromide, potassium bromide,
calcium bromide or magnesium bromide. It may also be a quaternary
ammonium or quaternary phosphonium salt such as tetramethylammonium
bromide, tetraethylammonium bromide, tetra-n-butylammonium bromide
or tetramethylphosphonium bromide, or a hexaalkylguanidinium salt
such as hexaethylguanidinium bromide.
[0016] Component C is at least one organic bisphosphine. By
"organic" is meant a compound containing at least one organic
radical, with the proviso that said compound may also contain
non-organic atoms or radicals. Thus, the bisphosphine may often be
characterized by the formula
(R.sup.1).sub.2P-R.sup.2-P(R.sup.1).sub.2, (I)
[0017] wherein each R.sup.1 is independently a monovalent organic
radical and R.sup.2 is a divalent organic radical. Most often,
R.sup.1 is an aromatic or alicyclic radical, preferably aromatic
and most preferably phenyl.
[0018] The identity of the divalent R.sup.2 radical is subject to
wide variation. It may be aliphatic, as exemplified by ethylene,
trimethylene, tetramethylene and neopentylene. It may also be
aromatic, as illustrated by phenylene and naphthylene. Suitable
radicals include those containing inorganic elements, as
illustrated by aminobis(alkylene) and ferrocenylene. For the most
part, aliphatic radicals are preferred and C.sub.3-8 aliphatic
radicals especially preferred.
[0019] Many bisphosphines of formula I, particularly the ones in
which R.sup.2 is aliphatic, are commercially available; examples
are 1,3-bis(diphenylphosphino)propane and
1,4-bis(diphenylphosphino)butane. Other bisphosphines can be
prepared by art-recognized methods.
[0020] Bisphosphines are included in the carbonylation catalyst
system in catalytic amounts. In this context a "catalytic amount"
is an amount of bisphosphine (or combination of bisphosphines) that
increases the number of moles of diaryl carbonate produced per mole
of Group VIII metal utilized; increases the number of moles of
diaryl carbonate produced per mole of halide utilized; or increases
selectivity toward diaryl carbonate production beyond that obtained
in the absence of the bisphosphine (or combination of
bisphosphines). Optimum amounts of a bisphosphine in a given
application will depend on various factors, such as the identity of
reactants and reaction conditions.
[0021] It is within the scope of the invention to introduce
component C, the bisphosphine, into the catalyst mixture as a
discrete compound. It is also contemplated to preform a complex of
the bisphosphine with the Group VIII metal of component A,
whereupon components A and C are introduced as a single entity.
This may be achieved, for example, by a ligand interchange reaction
between the bisphosphine and a palladium(II) halide complex with
another ligand such as acetonitrile.
[0022] The preparation of a palladium(II) bisphosphine complex is
illustrated by the following example.
EXAMPLE 1
[0023] A 100-ml round-bottomed flask was charged with 484.0 mg
(1.87 mmol) of commercial grade palladium(II) chloride-acetonitrile
complex and 30 ml of acetonitrile. The resulting solution was
heated to about 40.degree. C. with vigorous stirring until the
palladium salt completely dissolved; a bright orange homogeneous
solution resulted. To the stirred solution was added, in one
portion, 797.0 mg (1.87 mmol) of 1,4-bis(diphenylphosphino)-
butane. The phosphine readily dissolved, and a pale yellow
precipitate formed instantly. The suspension thus formed was
stirred for an additional 5 minutes at room temperature and then
cooled in an ice bath for 30 minutes to complete precipitation. The
pale yellow precipitate was filtered in air on a medium pore
fritted glass filter and washed with reagent grade hexane. It was
then dried under vacuum. The yield of the desired palladium(II)
chloride bisphosphine complex, whose structure was confirmed by
phosphorus-31 nuclear magnetic resonance spectroscopy, was 1.062 g,
or 94% of theoretical.
[0024] Also present in the catalyst composition is (D) at least one
cocatalyst which is a compound of a metal other than a heavy Group
VIII metal, preferably one which is soluble in the liquid phase
under the reaction conditions. Numerous other metal compounds are
known in the art to be active as carbonylation cocatalysts, and any
compound having such activity may be used according to the present
invention provided an improvement in diphenyl carbonate production,
usually yield, is achieved thereby.
[0025] Illustrative cocatalytic metals include cerium, titanium,
copper, zinc, manganese, bismuth, europium and lead, which may be
used singly or in combination. It should be noted, however, that
not all possible permutations of component D are operative in all
contexts; the effectiveness of any metal compound or combination of
compounds for this purpose may be determined by simple
experimentation. The preferred cocatalytic compounds are those of
lead.
[0026] Examples of lead compounds which may be employed are lead
oxides such as PbO and Pb.sub.3O.sub.4; inorganic lead salts such
as lead(II) nitrate; lead carboxylates such as lead(II) acetate,
lead(II)propionate and lead(IV) acetate; lead alkoxides and
aryloxides such as lead(II) methoxide and lead(II) phenoxide; and
lead salts of .beta.-diketones such as lead(II) 2,4-pentanedionate.
Mixtures of the aforementioned lead compounds may also be employed.
The preferred lead compounds are lead(II) oxide, lead(II)
aryloxides and lead(II) 2,4-pentanedionate. The preferred compounds
of other metals are, for the most part, salts of P-diketones and
especially 2,4-pentanedionates.
[0027] A subgenus of lead cocatalytic compounds that are
particularly useful according to the invention is the subgenus of
lead halophenoxides, typically having the formula
Pb.sub.nO.sub.m(OA).sub.(2-z)(n-m)X.sub.z(n-m), (II)
[0028] wherein A is an aromatic radical, X is chlorine or bromine,
n has a value in the range of 1-3, m has a value in the range of
0-1 and z has a value in the range of 0.1-2.0.
[0029] In formula II, A may be any aromatic radical, unsubstituted
or substituted. In general, A corresponds to the diaryl carbonate
to be formed in the carbonylation reaction. Therefore, it is
usually unsubstituted phenyl. X may be bromide or chloride and is
preferably bromide.
[0030] The values of n, m and z are as described hereinabove. Most
often, n is 2.5-3 and m is 0.8-1.
[0031] The lead halophenoxides may be prepared by merely bringing
into contact, usually at a temperature in the range of about
50-120.degree. C., lead(II) oxide, at least one bromide or chloride
salt and at least one hydroxyaromatic compound, most often phenol.
Suitable bromide and chloride salts include alkali metal and
alkaline earth metal bromides and chlorides and tetraalkylammonium,
tetraalkylphosphonium and hexaalkylguanidinium bromides and
chlorides. The bromides are strongly preferred. When the bromide or
chloride salt is an inorganic salt such as sodium bromide, the
reaction is preferably facilitated by the presence of an
electron-donating compound, especially a nitrile such as
acetonitrile.
[0032] The molar ratio of lead to halide in the reaction mixture
should be at least 2:1, since at lower molar ratios the principal
products are the lead(II) halides and hydroxyhalides. In general,
molar ratios in the range of about 2-20:1 are preferred. It should
be noted, however, that the molar ratio of lead to halide in the
product is not necessarily at least 2:1. Rather, the method of the
invention involves this minimum since it permits isolation of the
lead halophenoxide.
[0033] Hydroxyaromatic compound is most often present in excess and
is preferably employed as a solvent for the reaction. The
electron-donating compound, when employed, may also be present in
molar excess with respect to halide salt, typically in a molar
ratio in the range of about 50-200:1. Under such conditions, the
lead halophenoxide forms a separate phase, which may be isolated by
conventional methods including such operations as filtration and
drying.
[0034] The preparation of lead halophenoxides is illustrated by the
following, non-limiting Examples.
EXAMPLES 2-7
[0035] Various proportions of tetra-n-butylammonium bromide (TBAB)
or hexaethylguanidinium bromide (HEGB) and phenol (PhOH) were
combined with lead(II) oxide (PbO) and the resulting mixtures were
stirred overnight at 70.degree. C. After cooling to room
temperature, the solid precipitates were removed by filtration,
washed twice with acetonitrile and dried in a vacuum oven at
100.degree. C.
EXAMPLES 8-9
[0036] Lead(II) oxide (PbO), 2.715 g, was dissolved in 10 ml of
phenol (PhOH) at 100.degree. C. and the resulting solution was
added to various amounts of sodium bromide suspended in a mixture
of 5 ml of phenol and 5 ml of acetonitrile (ACN). The resulting
mixtures were stirred overnight at 100.degree. C. After cooling to
room temperature, the solid precipitates, which were the desired
lead bromophenoxides, were removed by filtration, washed twice with
acetonitrile and dried in a vacuum oven at 100.degree. C.
[0037] The proportions and analyses applicable to the products of
Examples 2-9 are given in Table I.
1TABLE I Example 2 3 4 5 6 7 8 9 Bromide: Identity TBAB TBAB HEGB
HEGB HEGB HEGB NaBr NaBr Amount, mg 570 2,850 540 510 570 155 150
75 PbO, mg 1,000 5,030 1,000 1,800 2,500 1,800 2,700 2,700 Molar
ratio, Pb/Br 2.5 2.55 2.55 4.4 6.8 16.0 8.3 16.6 Solvent: Identity
PhOH PhOH PhOH PhOH PhOH PhOH PhOH/ PhOH/ ACN ACN Amount, ml 10 50
10 10 10 10 20 20 Yield, %* 62.0 44.0 65.7 68.0 49.7 38.8 36.1 87.8
Br, % 8.0 8.8 8.3 5.2 5.4 2.1 6.3 1.4 Pb, % 62.9 61.8 63.5 62.0
60.9 58.7 60.3 58.6 *Based on PbO.
[0038] The presence of (E) a cosolvent in the catalyst system is
also often preferred. Suitable cosolvents include various polar
organic liquids such as ethers including polyethylene glycol
ethers, amides such as N-methylpyrrolidone, sulfones such as
sulfolane and nitrites such as acetonitrile and adiponitrile. It
should be noted, however, that component E is not effective to
optimize diaryl carbonate formation for all possible permutations
of component D; the combined effectiveness of the two for this
purpose may be determined by simple experimentation.
[0039] In addition to the aforementioned reactants and catalyst
system, it is strongly preferred for a desiccant to be present in
the reaction system. The preferred desiccants are non-reactive
materials such as molecular sieves, as illustrated by 3-Angstrom
(hereinafter "3A") molecular sieves. They are usually isolated from
the other reactants, as by presence in a basket mounted to a
stirrer shaft or the like.
[0040] Component A is most often present in the amount of about
0.1-10,000 ppm by weight of the appropriate Group VIII metal
(usually palladium), based on hydroxyaromatic compound, and
component B in the amount of about 1-2,000 equivalents of halide
per equivalent of the Group VIII metal of component A. Component C
is present in an amount effective to form a complex with the metal
of component A; this amount is generally at least a number of moles
equal to the number of gram-atoms of metal in said component A, and
preferably in a ratio of moles of component C to gram-atoms of said
metal in the range of about 1.0-1.2:1. Component D, when present,
is generally employed in the amount of about 0.2-200 gram-atoms of
total metal per equivalent of the Group VIII metal of component
A.
[0041] The role of component E in the composition and method of the
invention is believed to be to increase the degree of dissociation
and ionization of the halide anion of component B, perhaps by
forming a complex with the cationic portion of said component,
although the invention is in no way dependent on this or any other
theory of operation. The amount of component E employed will be an
amount effective to increase the yield of the desired diaryl
carbonate as evidenced, for example, by an increase in "turnover
number"; i.e., the number of moles of diaryl carbonate formed per
gram-atom of palladium present. This amount is most often about
1-60% by volume based on the total of hydroxyaromatic compound and
component E.
[0042] The method of the invention is preferably conducted in a
reactor in which the hydroxyaromatic compound and catalyst system
are charged under pressure of carbon monoxide and oxygen and
heated. The reaction pressure is most often within the range of
about 1-500 and preferably about 1-150 atm. Gas is usually supplied
in proportions of about 1-50 mole percent oxygen with the balance
being carbon monoxide and optionally one or more inert gases, and
in any event outside the explosion range for safety reasons. The
gases may be introduced separately or as a mixture. Reaction
temperatures in the range of about 60-150.degree. C. are typical.
It is often preferred to maintain a substantially constant gas
pressure and partial pressure of carbon monoxide and oxygen, as
described, for example, in U.S. Pat. No. 5,399,734, until
conversion of the hydroxyaromatic compound is complete.
[0043] The diaryl carbonates produced by the method of the
invention may be isolated by conventional techniques. It is often
preferred to form and thermally crack an adduct of the diaryl
carbonate with the hydroxyaromatic compound, as described in U.S.
Pat. Nos. 5,239,106 and 5,312,955.
[0044] The method of the invention is illustrated by the following
examples. Minor variations in reagent amounts from one example to
another are not believed significant from the standpoint of
yield.
EXAMPLES 10-14
[0045] In each experiment, a high pressure reactor equipped with a
stirrer was charged with approximately 61.318 g (651 mmol) of
phenol, 301 mg of the lead bromophenoxide of Example 3, 1,750 mg
(8.32 mmol) of tetraethylammonium bromide and a preformed mixture
of 4.8 mg (0.016 mmol) of palladium(II) 2,4-pentanedionate and
0.016 mmol of one of the following bisphosphines:
[0046] DPPP- 1,3-bis(diphenylphosphino)propane,
[0047] DPPB-1,4-bis(diphenylphosphino)butane,
[0048] DPPF-bis(diphenylphosphino)ferrocene,
[0049] DCPF-bis(dicyclohexylphosphino)ferrocene,
[0050] DPAP-bis(diphenylphosphino)propylamine.
[0051] Freshly activated Type 3A molecular sieves, 38 g, were
placed in a perforated polytetrafluoroethylene basket mounted on
the stirrer shaft.
[0052] The reactor was sealed, flushed twice with carbon monoxide,
pressurized with 88.4 atmospheres of a carbon monoxide-oxygen
mixture containing 7.5% oxygen by volume and heated for 5 hours at
100.degree. C., with vigorous stirring and periodic sampling via a
sample dip tube.
[0053] When the reaction was complete, the reactor contents were
cooled and analyzed. The results are given in Table II, as averages
of quadruplicate runs. "Turnover number" is the number of moles of
diaryl carbonate formed per gram-atom of palladium present, and
"selectivity" (to diphenyl carbonate) is the amount of diphenyl
carbonate produced as a percentage of total reaction products
derived from phenol. Comparison is made with a control in which no
bisphosphine was employed.
2 TABLE II Turnover Selectivity, Example Bisphosphine number % 10
DPPP 6,075 77.0 11 DPPB 5,260 82.3 12 DPPF 4,490 61.4 13 DCPF 4,690
56.0 14 DPAP 6,040 65.8 Control -- 4,340 67.2
[0054] As demonstrated in Table II, the turnover numbers in the
examples are higher than that of the control. In particular,
excellent turnover numbers are produced by the bisphosphines in
which R.sup.2 is aliphatic. Certain compositions of the invention
(Examples 10 and 11) also afford higher selectivities than the
control.
EXAMPLES 15-20
[0055] Carbonylation experiments were conducted in small vials,
employing a catalyst system containing 12 equivalents of lead(II)
oxide, 5.6 equivalents of cerium(III) 2,4-pentanedionate and 400
equivalents of tetraethylammonium bromide per equivalent of
palladium. The palladium catalysts were stored for various periods
before use, and the reaction mixtures in various examples were
stored at 70.degree. C. for various periods. The proportion of
palladium was 0.25 mmol per mmol of phenol and the reaction volume
was 25 .mu.l.
[0056] Each vial was capped with a snap cap having a slit with a
polytetrafluoroethylene septum and the vials were placed in an
autoclave which was pressurized to 88.4 atm with a mixture of 90
mole percent carbon monoxide and 10 mole percent oxygen and heated
at 100.degree. C. for 3 hours. The contents of the vials were
analyzed for diphenyl carbonate by vapor phase chromatography. The
results are given in Table III, in comparison with controls
employing palladium(II) 2,4-pentanedionate as a catalyst.
3TABLE III Heated Turnover Catalyst mixture Turnover number,
Example storage, hrs. storage, hrs. number control 15 4 4 1,926 801
16 4 2 2,036 891 17 4 0 2,132 2,510 18 2 2 2,000 841 19 2 0 1,879
2,330 20 0 0 2,018 2,368
[0057] It can be seen that the palladium(II) 2,4-pentanedionate
catalyst systems show a very significant decrease in turnover
number upon storage of the reaction mixture, although storage of
the catalyst itself has no significant effect (compare Examples 17,
19 and 20). By contrast, the turnover numbers resulting from use of
the catalyst systems of the present invention remain comparable
under the same conditions.
[0058] The same pattern was not observed in catalyst systems not
containing lead and cerium but containing copper(II)
2,4-pentanedionate, a homogeneous catalyst constituent. Turnover
numbers of the same order of magnitude were observed irrespective
of catalyst storage and reaction mixture storage for periods up to
20 and 4 hours, respectively.
EXAMPLES 21-53
[0059] Carbonylation experiments were conducted in small vials as
described in Examples 15-20, employing the palladium(II) chloride
bisphosphine complex of Example 1; sodium bromide (NaBr), calcium
bromide (CaBr.sub.2) or tri-n-butylammonium bromide (TBAB); and
various cosolvents at levels of 24 ppm of palladium based on
phenol, 240 equivalents of bromide per equivalent of palladium and
35% cosolvent by volume based on phenol-cosolvent mixture. Various
cocatalyst compounds which included lead(II) oxide, titanium(IV)
oxide bis(2,4-pentanedionate)- , zinc 2,4-pentanedionate,
copper(II) 2,4-pentanedionate, cerium(III) 2,4-pentanedionate,
iron(III) 2,4-pentanedionate, manganese(III) 2,4-pentanedionate,
europium(III) 2,4-pentanedionate and bismuth(III)
2,2,6,6-tetramethyl-3,5-heptanedionate, alone or in combination,
were employed as component E. The cosolvents employed were
N-methylpyrrolidone (NMP), tetraethylene glycol dimethyl ether
("tetraglyme" TEG), polyethylene glycol dimethyl ether (PEG),
sulfolane (SULF) and adiponitrile (ACN).The gas mixture consisted
of 91.7 mole percent carbon monoxide and 8.3 mole percent
oxygen.
[0060] The results are given in Table IV, as averages for
triplicate runs. Cocatalyst proportions are in equivalents per
equivalent of palladium. Comparison is made with controls in which
no cosolvent was used and the proportion of phenol was increased
correspondingly.
4TABLE IV Turnover Ex- Turnover number, ample Cocatalyst (eq)
Halide Cosolvent number control 21 Cu(20) NaBr NMP 713 222 22
Cu(20) NaBr TEG 1,023 222 23 Cu(20) NaBr PEG 1,065 222 24 Cu(20)
NaBr SULF 588 222 25 Ti(10), Zn(20) NaBr NMP 697 158 26 Ti(10),
Zn(20) NaBr TEG 483 158 27 Ti(10), Zn(20) NaBr PEG 429 158 28
Ti(10), Zn(20) NaBr SULF 735 158 29 Ti(10), Zn(20) NaBr ACN 600 158
30 Pb(24), Ce(10) NaBr NMP 1,342 665 31 Pb(24), Ce(10) NaBr TEG
1,456 665 32 Pb(24), Ce(10) NaBr PEG 1,318 665 33 Pb(24), Ce(10)
NaBr SULF 1,058 665 34 Pb(24), Ce(10) NaBr ACN 1,111 665 35 Pb(24),
Ti(5.6) NaBr NMP 1,373 547 36 Pb(24), Ti(5.6) NaBr TEG 1,321 547 37
Pb(24), Ti(5.6) NaBr PEG 613 547 38 Pb(24), Ti(5.6) NaBr SULF 962
547 39 Pb(24), Ti(5.6) NaBr ACN 835 547 40 Pb(24), Ce(10)
CaBr.sub.2 TEG 485 183 41 Cu(10), Fe(10) NaBr PEG 88 40 42 Cu(10),
Mn(10) NaBr NMP 161 100 43 Cu(10), Mn(10) NaBr TEG 420 100 44
Cu(10), Mn(10) NaBr PEG 377 100 45 Cu(10), Mn(10) NaBr SULF 233 100
46 Bi(20), Eu(20) NaBr NMP 270 146 47 Bi(20), Eu(20) NaBr TEG 333
146 48 Bi(20), Eu(20) NaBr PEG 304 146 49 Bi(20), Eu(20) NaBr SULF
289 146 50 Bi(20), Eu(20) NaBr ACN 365 146 51 Ce(10), Zn(50) TBAB
NMP 253 179 52 Ce(10), Zn(50) TBAB TEG 259 179 53 Ce(10), Zn(50)
TBAB PEG 222 179
[0061] Based on the above results, the benefit of using cosolvents
in these particular catalyst combinations is apparent.
[0062] It will be understood that each of the elements described
above, or two or more together, may also find utility in
applications differing from the types described herein. While the
invention has been illustrated and described as embodied in a
catalyst composition and method for producing diaryl carbonates
using bisphosphines, it is not intended to be limited to the
details shown, since various modifications and substitutions can be
made without departing in any way from the spirit of the present
invention. For example, additional effective IOCC compounds can be
added to the reaction. As such, further modifications and
equivalents of the invention herein disclosed may occur to persons
skilled in the art using no more than routine experimentation, and
all such modifications and equivalents are believed to be within
the spirit and scope of the invention as defined by the following
claims.
* * * * *