Method of making bisimides
View Patent ↗The present invention provides a method for preparing relatively insoluble bisimides under conditions which afford high imidization reaction rates and which permit the monitoring and adjustment of reactant stoichiometry at any stage of the reaction. The bisimides provided by the present invention are prepared either by reaction of a diamine such as 4,4′-diaminodiphenylsulfone (DDS) with an anhydride, for example 3-chlorophthalic anhydride (3-ClPA) in the presence of a solvent at a pressure greater than one atmosphere and at a temperature above the normal boiling point of the solvent, or by reaction of a monoamine with a dianhydride under the same conditions. In one embodiment, the relatively insoluble product bisimides provided by the present invention have a solubility in ortho-dichlorobenzene of less than about 10 percent by weight at a temperature of about 180° C.
1. A method for making a bisimide, the method comprising:
(a) adding a molten first reactant to a mixture comprising a solvent having a boiling point greater than 120° degrees Celsius at 1 atmosphere and a second reactant to provide a uniform reaction mixture wherein said first reactant is an anhydride and said second reactant is a diaminodiphenylsulfone;
(b) agitating the uniform reaction mixture while removing water formed in an imidization reaction to afford a uniform product mixture comprising a product bisimide, the product bisimide being present in an amount corresponding to at least 20 percent solids, the product bisimide having a solubility in ortho-dichlorobenzene of less than about 10 percent by weight at a temperature of about 180° C.;
said adding and said agitating being carried out at a temperature of 210-230° C.,
wherein the dianhydride comprises a haloaromatic anhydride, a phthalic anhydride, a nitrophthalic anhydride, 4-cyanophthalic anhydride, or a dianhydride of structure (VI)
wherein R 1 is a halogen atom, a nitro group, a C 1 - C 12 aliphatic radical, C 3 -C 12 cycloaliphatic radical, or a C 3 -C 12 aromatic radical; b is independently at each occurrence 0 or an integer from 1 to 3; and W is a bond, an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, a selenium atom, a hexafluoroisopropylidene group, a C 1 - C 30 aliphatic radical, a C 3 -C 30 cycloaliphatic radical, or a C 3 - C 30 aromatic radical, or a carbonyl group.
2. The method according to claim 1 , wherein the solvent is selected from the group consisting of ortho-dichlorobenzene, para-dichlorobenzene, chlorobenzene, dichlorotoluene, 1,2,4-trichlorobenzene, diphenyl sulfone, phenetole, anisole, veratrole, toluene, xylene, mesitylene, o-cresol, and mixtures thereof.
3. The method according to claim 1 , wherein the solvent is ortho-dichlorobenzene.
4. The method according to claim 1 , wherein the first reactant is a haloaromatic anhydride.
5. The method according to claim 4 , wherein the haloaromatic anhydride is selected from the group consisting of 3-ClPA, 4-ClPA, and mixtures thereof.
6. The method according to claim 1 , wherein the uniform product mixture comprises less than about 0.15% by weight of a monoamine impurity.
7. The method according to claim 1 , wherein said first reactant comprises phthalic anhydride.
8. The method according to claim 1 , wherein the product bisimide has a solubility in ortho-dichlorobenzene of less than 5 percent by weight at a temperature of about 180° C.
9. The method according to claim 1 , wherein the first reactant is used in a stoichiometric excess of about 0.3 percent.
10. The method according to claim 1 , further comprising verifying the stoichiometry of the reaction mixture.
11. The method according to claim 10 , further comprising introducing additional first reactant or additional second reactant in response to a stoichiometry verification step.
12. A method for making a bisimide, the method comprising:
(a) adding molten chlorophthalic anhydride to a mixture comprising ortho-dichlorobenzene and 4,4′-diaminodiphenylsulfone to provide a uniform reaction mixture wherein the mixture is at a temperature greater than 210° C.;
(b) agitating the uniform reaction mixture while removing water formed in an imidization reaction to afford a uniform product mixture comprising a product bisimide, the product bisimide being present in an amount corresponding to at least 20 percent solids, the product bisimide having a solubility in ortho-dichlorobenzene of less than about 10 percent by weight at a temperature of about 180° C.;
said agitating being carried out at a temperature greater than the boiling point of the ortho-dichlorobenzene at a pressure greater than 1 atmosphere.