Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-11-20
2002-06-04
Solola, T. A. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C562S485000, C562S494000
Reexamination Certificate
active
06399790
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method for oxidizing xylene derivatives. More particularly, the invention relates to a method for oxidizing a substrate comprising at least one halo-ortho-xylene in the presence of at least one metal catalyst, at least one solvent, and optionally at least one promoter to provide a product comprising halo-phthalic acid or halo-phthalic anhydride. In one key embodiment the invention relates to a method for producing a product comprising 4-chlorophthalic acid or 4-chlorophthalic anhydride.
Methods for oxidizing ortho-xylene are known. For example, U.S. Pat. No. 3,402,184 describes oxidation of ortho-xylene in acetic acid solvent in the presence of a bromine promoter. U.S. Pat. Nos. 5,958,821, 5,981,420, and 6,020,522 describe oxidation of ortho-xylene in acetic acid solvent in the presence of a hydroxyimide promoter. Methods for preparing 4-chlorophthalic anhydride are also known. However, these methods typically involve aromatization of a Diels-Alder adduct of chloroprene and a maleic anhydride as in U.S. Pat. No. 5,322,954, or chlorination of phthalic acid as in Japanese patent applications 07258152 and 02129143. The latter chlorination process may produce polychlorinated biphenyls (PCBs). There is a need for a method for producing 4-chlorophthalic anhydride which does not involve handling toxic chloroprene or chlorine gas, and which does not produce PCBs.
SUMMARY OF THE INVENTION
In one embodiment the invention is a method for oxidizing a substrate comprising at least one halo-ortho-xylene which comprises combining the substrate in a solvent with at least one metal catalyst and heating in the presence of an oxygen source to produce a product mixture.
In another embodiment the invention is a method for oxidizing a substrate comprising 4-chloro-ortho-xylene which comprises combining chloro-ortho-xylene in acetic acid solvent with at least one metal catalyst which is a metal compound comprising cobalt, and heating in the presence of an oxygen source to produce a product mixture comprising 4-chlorophthalic acid or 4-chlorophthalic anhydride.
In still another embodiment the invention is a method for producing a product mixture comprising 4-chlorophthalic acid or 4-chlorophthalic anhydride which comprises oxidizing a substrate comprising 4-chloro-ortho-xylene, optionally in the presence of chlorotoluic acid, which comprises the steps of
(i) combining substrate in acetic acid solvent with at least one metal catalyst comprising cobalt, and optionally manganese, and heating in the presence of an oxygen source to a temperature in a range of between about 100° C. and about 230° C. at pressure in a range of between about 1300 and about 8300 kilopascals, wherein the molar ratio of substrate to the at least one metal catalyst is in a range of about 80-250:1; and
(ii) isolating product comprising 4-chlorophthalic acid or 4-chlorophthalic anhydride.
DETAILED DESCRIPTION; PREFERRED EMBODIMENTS
In one embodiment the substrate comprising at least one halo-ortho-xylene of the present invention preferably comprises a monohalo-ortho-xylene, more preferably 4-halo-ortho-xylene, most preferably 4-fluoro- or 4-chloro-ortho-xylene. In another embodiment the substrate comprises a mixture of 4-halo- and 3-halo-ortho-xylene, preferably a mixture of 4-fluoro- and 3-fluoro-ortho-xylene or a mixture of 4-chloro- and 3-chloro-ortho-xylene. When 3-halo-ortho-xylene is present, it comprises about 0.001-15 molar percent, preferably about 0.01-12 molar percent, and more preferably about 0.1-10 molar percent of total substrate.
In yet another embodiment the substrate comprises at least one halo-ortho-xylene as described above, optionally in the presence of at least one halotoluic acid, preferably at least one chlorotoluic acid (also known as chloro methylbenzoic acid), more preferably either (a) 4-chloro-2-methyl benzoic acid or (b) 5-chloro-2-methylbenzoic acid or (c) a mixture thereof, and still more preferably a mixture of either or both of (a) and (b) with either (d) 4-halo-ortho-xylene, or (e) a mixture of 4-halo- and 3-halo-ortho-xylene. Halo-toluic acid may be either added to the substrate or may be present as a consequence of partial oxidation of halo-ortho-xylene. As a consequence of partial oxidation the amount of halo-toluic acid in the substrate will vary with such factors as reaction temperature, time, and catalyst.
In still another embodiment the substrate comprises a mixture of ortho-xylene with halo-ortho-xylene, preferably either with (d) 4-halo-ortho-xylene, or with (e) a mixture of 4-halo- and 3-halo-ortho-xylene, or with at least one halotoluic acid, preferably chlorotoluic acid, or with a mixture of chlorotoluic acid with either (d) 4-halo-ortho-xylene, or (e) a mixture of 4-halo- and 3-halo-ortho-xylene. When ortho-xylene is present, it comprises about 0.001-10 molar percent and preferably about 0.01-1 molar percent of total substrate. An especially preferred substrate comprises 4-chloro-ortho-xylene, optionally in combination with at least one of 3-chloro-ortho-xylene, ortho-xylene, or chlorotoluic acid.
The substrate comprising at least one halo-ortho-xylene is combined in the reaction mixture with at least one solvent, which preferably comprises a lower aliphatic carboxylic acid. Illustrative examples of lower aliphatic carboxylic acids employed in the process of the present invention, include, but are not limited to, acetic acid, propionic acid, butanoic acid, pentanoic acid, or hexanoic acid. Acetic acid is preferred.
At least one metal catalyst is used in the present invention. The at least one metal catalyst comprises a metal compound with a metal selected from the group consisting of cobalt, manganese, vanadium, copper, molybdenum, and iron, and mixtures thereof. Preferably, a metal compound is a salt of the metal and more preferably an acetate or acetylacetonate of the metal. Illustrative metal compounds which are suitable for use in the invention include, but are not limited to, cobalt dibromide hexahydrate, cobalt dichloride, cobalt (II) acetate, cobalt (II) acetylacetonate, cobalt (III) acetylacetonate, cobalt (II) hexafluoroacetylacetonate, cobalt (II) picolinate, manganese (III) acetate, manganese (II) acetate, manganese (II) hexafluoroacetylacetonate trihydrate, manganese (III) acetylacetonate, manganese (II) acetylacetonate, manganese dichloride tetrahydrate, manganese dibromide, manganese (II) picolinate, manganese (III) picolinate, manganese (III) bromide acetylacetonate, vanadyl (IV) acetate (VO[OC(O)CH
3
]
2
), vanadyl (IV) acetylacetonate, copper (I) acetate, molybdenyl (VI) acetylacetonate (MoO
2
[C
5
H
7
O
2
]), iron (II) acetate, and hydrates, and anhydrous compounds, and mixtures thereof. Preferred metal catalysts include mixtures of cobalt (II) bromide hexahydrate with either cobalt (II) picolinate, manganese (II) bromide, manganese (II) chloride tetrahydrate, manganese (III) bromide acetylacetonate, manganese (II) acetate, manganese (III) acetate dihydrate, manganese (II) acetylacetonate, manganese (III) acetylacetonate, or manganese (II) hexafluoroacetylacetonate trihydrate; mixtures of cobalt (II) acetate with manganese (III) acetate or manganese (II) bromide; and ternary mixtures of cobalt (II) acetate with manganese (III) acetate and manganese (II) bromide; or of cobalt (II) acetate with manganese (III) acetate and cobalt (II) bromide; or of cobalt (II) acetate with manganese (III) acetate and iron (II) bromide; or of cobalt (II) acetate with manganese (III) acetate and either copper (I) bromide or copper (II) bromide.
The molar ratio of halo-ortho-xylene substrate to the at least one metal catalyst is in a range of about 20-600:1, preferably in a range of about 50-300:1, and most preferably in a range of about 80-250:1. In especially preferred embodiments the molar ratio of halo-ortho-xylene substrate to the at least one metal catalyst is about 200:1. The at least one metal catalyst may be added in one portion to the substrate or in more than one portion during the course of the reacti
Caringi Joseph John
Moasser Bahram
Schattenmann Sheree Lynell
Brown S. Bruce
General Electric Company
Johnson Noreen C.
Solola T. A.
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