Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2002-10-22
2003-07-08
Solola, Taofiq (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
active
06590108
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates to a method for the manufacture of poly(etherimide)s. More particularly, it relates to a method for the preparation of dianhydrides that can facilitate the manufacture of poly(etherimide)s without an intermediate nitration step.
Polyetherimides are high heat engineering plastics having a variety of uses. As disclosed in U.S. Pat. Nos. 4,417,044; 4,599,429; 4,902,809; and 4,921,970, the present commercial process for the synthesis of polyetherimides requires nitration of N-methylphthalimide to yield 4-nitro-N-methylphthalimide. Nitration often results in the formation of byproducts, which must be separated. In the next step of the process, 4-nitro-N-methylphthalimide is treated with the disodium salt of a dihydroxy compound, usually a bis(phenol) such as bisphenol A, to yield a bisimide (I) having the following general structure:
Suitable displacement reactions are disclosed in U.S. Pat. No. 4,257,953. Displacement is also disclosed in U.S. Pat. Nos. 5,132,423 and 5,872,294. Bisimide (I) is then reacted with a phthalic anhydride in an exchange reaction as disclosed in U.S. Pat. Nos. 4,318,857, 4,329,291, 4,329,292, 4,329,496, and 4,340,545 to yield the dianhydride (II):
Reaction of dianhydride (II) with a diamine results in polymerization to a poly (etherimide). Methods which improve or even eliminate any of the preceding steps would result in an improved synthesis of poly(etherimide)s.
SUMMARY OF INVENTION
A new method for the synthesis of poly(etherimide)s which eliminates the nitration step comprises synthesis and reaction of a substituted N-alkylphthalimide (III)
with the disodium salt of a dihydroxy compound such as a bis(phenol) to yield the bis (imide) (IV)
Bis(imide) (IV) is then subjected to transimidation to yield the dianhydride (V)
Transimidation is effected in the presence of a substituted phthalic anhydride, which yields a substituted N-alkylphthalimide that corresponds to the substituted phthalic anhydride as a by-product. By-product substituted N-alkylphthalimide may then be recycled for use in the formation bisimide (IV).
In another embodiment, transimidation is effected in the presence of 4-substituted tetrahydrophthalic anhydride, which yields a 4-substituted N-alkyltetrahydrophthalimide as a by-product. The by-product 4-substituted N-alkyltetrahydrophthalimide may be converted by aromatization to a 4-substituted N-alkylphthalimide, which may be used in the formation of bis(imide) (IV).
Finally, the reaction of dianhydride (V) with a diamine (VI) having the structure
H
2
N—R—NH
2
(VI)
yields poly(etherimide)s. This route obviates the need for the intermediate nitration step required by the prior art synthesis.
DETAILED DESCRIPTION
A convenient route for the manufacture of poly(etherimide)s comprises synthesis and reaction of a substituted N-alkylphthalimide (III):
wherein the alkyl group is a branched or straight chain alkyl group having from one to about 18 carbons. Preferably, the alkyl group is a methyl group. The substituent (X) is a nitro, chloro, bromo, or fluoro in the 3- or 4- position. Substituted N-alkylphthalimides may be obtained by the treatment of the corresponding substituted phthalic anhydride with a primary amine having the formula H
2
N-alkyl via a melt reaction, for example by contact of a gaseous primary amine such as methylamine with molten 4-halophthalic anhydride. Halophthalic anhydrides may be obtained by aromatization of the corresponding halotetrahydrophthalic anhydrides as disclosed in U.S. Pat. Nos. 5,233,054, 5,003,088, 5,059,697 and 4,978,760. Halophthalic anhydrides may also be obtained by the aromatization of the corresponding halotetrahydophthalic anhydrides in the presence of a catalyst such as a transition metal oxide. Nitro substituted phthalic anhydrides may be obtained by the nitration of phthalic anhydrides as taught in U.S. Pat. No. 5,155,234.
Displacement of the substituent of the substituted N-alkylphthalimide (III) may be effected by treatment with the disodium salt of a dihydroxy compound having the formula (VII)
HO—S—OH (VII)
to yield the bis(imide) (IV)
wherein S is a divalent radical, for example a straight or branched chain alkylene group having from about 2 to about 20 carbon atoms; a cycloalkylene group having from about 3 to about 20 carbon atoms; or an arylene group having from 6 to about 20 carbon atoms, and halogenated derivatives thereof. The alkylene, cycloalkylene, and arylene groups may be further substituted with alkyl, halogenated alkyl, fluoro, alkoxy, nitro, phenyl, phenoxy, aryl or other groups, provided that such substitutions do not interfere with synthesis or reaction. The displacement reaction between the dihydroxy compound and the substituted N-alkylphthalimide may be conducted in an inert solvent such as toluene, xylene, chlorobenzene or dichlorobenzene in the presence of a phase transfer catalyst such as hexaethylguanidinium chloride at a temperature in the range of about 110 to about 180° C. as taught in U.S. Pat. No. 5,132,423, which is incorporated by reference herein. Displacement may also occur in the melt phase with the substituted N-alkyphthalimide.
A particularly preferred dihydroxy compound is bis(phenol) (VIII)
wherein T is a single bond linking the two aryl groups, or a divalent radical, for example a straight or branched chain alkylene group having from one to about 20 carbon atoms; a cycloalkylene group having from about 3 to about 20 carbon atoms; or an arylene group having from 6 to about 20 carbon atoms, and halogenated derivatives thereof. The alkylene, cycloalkylene, and arylene groups may be further substituted alkyl, halogenated alkyl, fluoro, alkoxy, nitro, phenyl, phenoxy, aryl or other groups, provided that such substitutions do not interfere with synthesis or reaction. T further includes divalent functional groups such as sulfide, carbonyl, sulfoxide, and ether and divalent radicals of formula (XV)
Illustrative examples of bis(phenol)s of formula (VIII) include 2,2-bis[4-hydroxyphenyl]propane; 4,4′-bis(4-hydroxyphenyl)diphenyl ether; 4,4′-bis(4-phenoxy)diphenyl sulfide; 4,4′-bis(4-hydroxyphenyl)benzophenone; 4,4′-bis(4-hydroxyphenyl)diphenyl sulfone; 2,2-bis[4-(3-hydroxyphenyl)phenyl]propane; 4,4′-bis(3-hydroxyphenyl)diphenyl ether; 4,4′-bis(3-hydroxyphenyl)diphenyl sulfide; 4,4′-bis(3-hydroxyphenyl)benzophenone; 4,4′-bis(3-hydroxyphenyl)diphenyl sulfone; 4-(3-hydroxyphenyl)-4′-(4-hydroxyphenyl)diphenyl-2,2-propane; 4-(3-hydroxyphenyl)-4′-(4-hydroxyphenyl)diphenyl ether; 4-(3-hydroxyphenyl)-4′-(4-hydroxyphenyl)diphenyl sulfide; 4-(3-hydroxyphenyl)-4′-(4-hydroxyphenyl) benzophenone, and 4-(hydroxyphenyl)-4′-(4-hydroxyphenyl)diphenyl sulfone dianhydride, as well as various mixtures thereof. These and other bis(phenol)s and dihydroxy compounds are described in U.S. Pat. Nos. 3,972,902 and 4,455,410.
Bis(imide) (IV) is treated with a substituted phthalic anhydride (IX)
via transimidation to yield dianhydride (V)
wherein S is as described above. Useful substituted phthalic anhydrides have a nitro, chloro, bromo, or fluoro group in the 3 or 4 position although chloro and bromo substituents are preferred. Also preferred are mixtures of structural isomers, for example a mixture comprising 3-halophthalic anhydride and 4-halophthalic anhydride. Surprisingly, reaction conditions may be adjusted so as to minimize the formation of the N-alkylamino-N-alkylphthalimide (from the displacement of the halo group with alkylamine), a highly colored by-product which can impart an undesirable color to the product dianhydride. Preferably, the YI of the product is less than about 25, and more preferably less than about 15 as measured by the UV spectrum of the product.
A desired by-product of this reaction is substituted N-alkylphthalimide (III), which may be isolated and used for reaction with a dihydroxy compound (VII) as described above.
In an alternative embodiment, transimidization of bis(imide) (IV) is effected in the pr
Guggenheim Thomas Link
Odle Roy Ray
Swatos William James
Vollmer Michael J.
General Electric Company
Solola Taofiq
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