Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2002-03-22
2003-12-02
Shah, Mukund J. (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S246000, C562S416000
Reexamination Certificate
active
06657068
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates to liquid phase oxidation of halogen substituted alkyl aromatic compounds. In particular, the invention relates to liquid phase oxidation of halo-ortho-xylene to produce halophthalic acid which can be dehydrated to produce halophthalic anhydride.
Liquid phase oxidation has long been used to produce dicarboxylic acids from dialkyl benzenes. Of particular interest has been the oxidation of dimethyl benzene (xylene) to phthalic acid, especially the oxidation of para-xylene to terephthalic acid, which is used in the production of polybutylene terephthalate. The liquid phase oxidation of xylene to phthalic acid requires the use of a catalyst, typically a cobalt/manganese/bromine catalyst system, and is generally performed in a carboxylic acid solvent such as acetic acid. The catalyst system may be augmented by the use of a co-catalyst such as zirconium, hafnium or cerium. Phthalic acid is an easily isolable solid, which can be filtered out of the reaction mixture.
Liquid phase oxidation, using a cobalt/manganese/bromine catalyst system and a carboxylic acid solvent, has also been applied to halogenated xylene with some success. The oxidation of the halogenated xylene is more difficult than the oxidation of xylene due to presence of a halogen, which is an electron withdrawing substituent, on the benzene ring. The greater difficulty in oxidation results in a lower reaction selectivity and a larger amount of partial oxidation and side products than seen in the liquid phase oxidation of xylene under similar conditions. Additionally, halogenated phthalic acid is difficult to separate from the partial oxidation and side products, even by distillation. Thus it is clear that in order for a method of liquid phase oxidation of halogenated xylene to be commercially successful the reaction yield and the reaction selectivity must be very high. Optimally, for a useful commercial process, the reaction selectivity should be high enough to result in only negligible amounts of partial oxidation and side products thus removing the need for isolation of halophthalic acid.
SUMMARY OF INVENTION
A method for the manufacture of halophthalic acid comprises forming a reaction mixture comprising a mixture of about 7 to about 3 parts by weight of acetic acid to 1 part by weight of a halo-ortho-xylene, about 0.25 to about 2 mole percent, based on the halo-ortho-xylene, of a cobalt source, about 0.1 to about 1 mole percent, based on the halo-ortho-xylene, of a manganese source, about 0.01 to about 0.1 mole percent, based on the halo-ortho-xylene, of a source of a metal selected from zirconium, hafnium and mixtures thereof, and about 0.02 to about 0.1 mole percent, based on the halo-ortho-xylene, of a bromide source; maintaining the reaction mixture at a pressure of at least about 1600 kilopascals (Kpa) and at a temperature of about 130° C. to about 200° C.; introducing a molecular oxygen containing gas to the reaction mixture at a rate of at least about 0.5 normal m
3
of gas/hour per kilogram (kg) of halo-ortho-xylene in the reaction mixture for a time sufficient to provide at least about 90 percent conversion of the halo-ortho-xylene to halophthalic acid.
In another embodiment, a method for the manufacture of halophthalic anhydride comprises forming a reaction mixture comprising a mixture of about 7 to about 3 parts by weight of acetic acid to 1 part by weight of a halo-ortho-xylene, about 0.25 to about 2 mole percent, based on said halo-ortho-xylene, of a cobalt source, about 0.1 to about 1 mole percent, based on said halo-ortho-xylene, of a manganese source, about 0.01 to about 0.1 mole percent, based on said halo-ortho-xylene, of a source of a metal selected from zirconium, hafnium and mixtures thereof, and about 0.02 to about 0.1 mole percent, based on said halo-ortho-xylene, of a bromide source; maintaining said reaction mixture at a pressure of at least about 1600 Kpa and at a temperature of about 130° C. to about 200° C.; introducing a molecular oxygen containing gas to the reaction mixture at a rate of at least about 0.5 normal m
3
of gas/kg of halo-ortho-xylene for a time sufficient to provide at least about 90 percent conversion of said halo-ortho-xylene to halophthalic acid with less than about 600 parts per million (ppm) of halophthalide; removing the acetic acid and any water formed as a result of the reaction by distillation; and dehydrating the halophthalic acid to form halophthalic anhydride.
In another aspect, the method for the manufacture of halophthalic acid comprises forming a reaction mixture comprising a mixture of about 7 to about 3 parts by weight of acetic acid to 1 part by weight of a halo-ortho-xylene, about 0.8 to about 1.2 mole percent, based on the halo-ortho-xylene, of a cobalt source, about 0.4 to about 0.6 mole percent, based on the halo-ortho-xylene, of a manganese source, about 0.04 to about 0.06 mole percent, based on the halo-ortho-xylene, of a source of a metal selected from zirconium, hafnium and mixtures thereof, and less than about 0.04 mole percent, based on the halo-ortho-xylene, of a source of bromide; maintaining the reaction mixture at a pressure of at least about 1600 Kpa and at a temperature of about 130° C. to about 200° C.; introducing a molecular oxygen containing gas to the reaction mixture at a rate of at least about 0.5 normal m
3
of gas/kg of halo-ortho-xylene for a time sufficient to provide at least about 90 percent conversion of said halo-ortho-xylene to halophthalic acid.
In another aspect, a method for the manufacture of halophthalic anhydride comprises forming a reaction mixture comprising a mixture of about 7 to about 3 parts by weight of acetic acid to 1 part by weight of a halo-ortho-xylene, about 0.8 to about 1.2 mole percent, based on said halo-ortho-xylene, of cobalt acetate or cobalt acetate hydrate, about 0.4 to about 0.6 mole percent, based on said halo-ortho-xylene, of manganese acetate or manganese acetate hydrate, about 0.04 to about 0.06 mole percent, based on said halo-ortho-xylene, of zirconium acetate or zirconium acetate hydrate, less than about 0.04 mole percent, based on said halo-ortho-xylene, of sodium bromide; maintaining said reaction mixture at a pressure of at least about 1600 Kpa and at a temperature of about 130° C. to about 200° C.; introducing a molecular oxygen containing gas to said reaction mixture at a rate of at least about 0.5 normal m
3
of gas/kg of halo-ortho-xylene in the reaction mixture for a time sufficient to provide at least about 90 percent conversion of said halo-ortho-xylene to halophthalic acid; removing the acetic acid and any water formed as a result of the reaction by distillation; separating the water from the acetic acid and recycling the acetic acid; and dehydrating the halophthalic acid to form halophthalic anhydride.
In another embodiment, a method for the manufacture of polyetherimide comprises forming a reaction mixture comprising a mixture of about 7 to about 3 parts by weight of acetic acid to 1 part by weight of a halo-ortho-xylene, about 0.25 to about 2 mole percent, based on the halo-ortho-xylene, of a cobalt source, about 0.1 to about 1 mole percent, based on the halo-ortho-xylene, of a manganese source, about 0.01 to about 0.1 mole percent, based on the halo-ortho-xylene, of a source of a metal selected from zirconium, hafnium and mixtures thereof, about 0.02 to about 0.1 mole percent, based on the halo-ortho-xylene, of a bromide source; maintaining the reaction mixture at a pressure of at least about 1600 KPa and at a temperature of about 130° C. to about 200° C.; introducing a molecular oxygen containing gas to the reaction mixture at a rate of at least about 0.5 normal m
3
of gas/kg of halo-ortho-xylene for a time sufficient to provide at least about 90 percent conversion of the halo-ortho-xylene to halophthalic acid with less than about 600 parts per million (ppm) of halophthalide; removing the acetic acid and any water formed as a result of the reaction by distillation; dehydrating the halophthalic acid to form halophthalic anhyd
Colborn Robert Edgar
Hall David Bruce
Koch Peter
Oeckel Gerald
General Electric Company
Tucker Zachary C.
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