Organic compounds -- part of the class 532-570 series – Organic compounds – Carbonate esters
Reexamination Certificate
2000-02-22
2001-01-16
Ambrose, Michael G. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbonate esters
C558S271000, C558S272000, C558S273000, C502S324000
Reexamination Certificate
active
06175033
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention is directed to a method and catalyst system for producing aromatic carbonates and, more specifically, to a method and catalyst system for producing diaryl carbonates through the carbonylation of aromatic hydroxy compounds.
2. Discussion of Related Art
Aromatic carbonates find utility, inter alia, as intermediates in the preparation of polycarbonates. For example, a popular method of polycarbonate preparation is the melt transesterification of aromatic carbonates with bisphenols. This method has been shown to be environmentally superior to previously used methods which employed phosgene, a toxic gas, as a reagent and chlorinated aliphatic hydrocarbons, such as methylene chloride, as solvents.
Various methods for preparing aromatic carbonates have been previously described in the literature and/or utilized by industry. A method that has enjoyed substantial popularity in the literature involves the direct carbonylation of aromatic hydroxy compounds with carbon monoxide and oxygen. In general, practitioners have found that the carbonylation reaction requires a rather complex catalyst system. For example, in U.S. Pat. No. 4,187,242, which is assigned to the assignee of the present invention, Chalk reports that a carbonylation catalyst system should contain a Group VIII B metal, such as ruthenium, rhodium, palladium, osmium, iridium, platinum, or a complex thereof. Further refinements to the carbonylation reaction include the identification of organic co-catalysts, such as terpyridines, phenanthrolines, quinolines and isoquinolines in U.S. Pat. No. 5,284,964 and the use of certain halide compounds, such as quaternary ammonium or phosphonium halides in U.S. Pat. No. 5,399,734, both patents also being assigned to the assignee of the present invention.
Unfortunately, due to the significant expense of using a Group VIII B metal as the primary catalyst in a bulk process, the economics of the aforementioned carbonylation systems is strongly dependent on the number of moles of aromatic carbonate produced per mole of Group VIII B metal utilized (i.e. “catalyst turnover”). Consequently, much work has been directed to the identification of efficacious co-catalyst combinations that increase primary catalyst turnover. For example, in U.S. Pat. No. 5,231,210, which is also assigned to the present assignee, Joyce et al. report the use of a cobalt pentadentate complex as an inorganic co-catalyst (“IOCC”). In U.S. Pat. No. 5,498,789, Takagi et al. report the use of lead as an IOCC. In U.S. Pat. No. 5,543,547, Iwane et al. report the use of trivalent cerium as an IOCC. In U.S. Pat. No. 5,726,340, Takagi et al. report the use of lead and cobalt as a binary IOCC system.
Until the work underlying the teachings of the present disclosure, however, few or no resources have been dedicated to identifying effective substitutes for the Group VIII B metal (typically palladium) as the primary catalyst in the carbonylation reaction. Given the recent, substantial increases in the cost of palladium, even substitutes exhibiting comparatively low activity can be economically viable.
Unfortunately, the literature is not instructive regarding the role of many catalyst components in the carbonylation reaction (i.e. the reaction mechanism), and meaningful guidance regarding the identification of effective combinations of catalyst system components is cursory at best. Accordingly, due to the lack of guidance in the literature, the identification of effective carbonylation catalyst systems has become a serendipitous exercise.
As the demand for high performance plastics has continued to grow, new and improved methods of providing product more economically are needed to supply the market. In this context, various processes and catalyst systems are constantly being evaluated; however, the identities of additional economically effective catalyst systems for these processes continue to elude the industry. Consequently, a long felt, yet unsatisfied need exists for economically superior methods and catalyst systems for producing aromatic carbonates and the like.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a method and catalyst system for producing aromatic carbonates. In one embodiment, the method includes the step of contacting at least one aromatic hydroxy compound with oxygen and carbon monoxide in the presence of a carbonylation catalyst system having an effective amount of a manganese source in the absence of an effective amount of a Group VIII B metal source.
In various alternative embodiments, the carbonylation catalyst system can include catalytic amounts of at least one inorganic co-catalyst, as well as effective amounts of a halide composition and/or a base.
REFERENCES:
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Patel Ben Purushotam
Shalyaev Kirill Vladimirovich
Soloveichik Grigorii Lev
Whisenhunt, Jr. Donald Wayne
Ambrose Michael G.
General Electric Company
Johnson Noreen C.
Stoner Douglas E.
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