| PATENT ASSIGNEE'S COUNTRY | USA |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 21.03.2000 |
| PATENT TITLE |
Cyclic oligomers comprising m-phenylene isophthalamide and polymers thereof |
| PATENT ABSTRACT |
Disclosed herein are cyclic oligomers comprising substituted or unsubstituted m-phenylene isophthalamide, complexes of these oligomers with selected metal salts, novel methods for their preparation, and polymerization of the cyclic oligomers to linear aramids. The aramids are useful, for example, as fibers for fire resistant clothing. Amino-functional cyclic oligomers may be reacted with polyfunctional acyl halides to produce polyamides. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | March 6, 1998 |
| PATENT REFERENCES CITED |
W. Memeger Jr., et al., Macromolecules, 26, 3476-3484, 1993. W. Memeger, Jr., Polym. Prepr., 34, 71-72, 1993. F. E. Elhadi et al., Tetrahedron Lett., 21, 4215-4218, 1980. T. L. Guggenheim et al., Polymer Prepr., 30, 138-139, 1989. Y. H. Kim et al., Abstracts of the 35th IUPAC Inter. Symposium on Macromolecules, University of Akron, Jul. 11-15, 1994. |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A polymer, which is a reaction product of a compound of the formula ##STR6## with a compound of the formula R.sup.13 (COX).sub.2 (V) wherein each R.sup.7, R.sup.8, R.sup.9, R.sup.10, R.sup.11, and R.sup.12 is independently amino or hydrogen; R.sup.13 is hydrocarbylene, X is halogen, provided that: a total of at least two of R.sup.7, R.sup.8, R.sup.9, R.sup.10, R.sup.11, and R.sup.12 are amino; the molar ratio of (V):(IV) is at least about 1:1; and the molar ratio of (V):(IV) is such that number of equivalents of COX groups in the reaction does not substantially exceed the number of amino groups. 2. The polymer as recited in claim 1 wherein X is chlorine, all of R.sup.7, R.sup.9, and R.sup.11 are amino, and all of R.sup.8, R.sup.10 and R.sup.12 are hydrogen. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
FIELD OF THE INVENTION Described herein are cyclic oligomers comprising substituted or unsubstituted m-phenylene isophthalamides, their preparation, their complexes with certain metals salts, and their polymerization to corresponding linear polyamides. TECHNICAL BACKGROUND Cyclic oligomers with repeat units corresponding to condensation polymers such as polyesters and polycarbonates are known. These cyclic oligomers can often be converted to their corresponding linear polymers by ring-opening polymerization. Cyclic oligomers of some aromatic amides have been made. Cyclic oligomers of (substituted) p-phenylene terephthalamide have been prepared. See, for example, W. Memeger Jr., et al., Macromolecules, vol. 26, p. 3476-3484 (1993) and Polym. Prepr., vol. 34, p. 71-72 (1993). No cyclic meta-substituted aromatic amides are disclosed in this paper. F. E. Elhadi, et al., Tetrahedron Lett., vol. 21, p. 4215-4218 (1980) reports the synthesis of N-substituted cyclic trimers of m-aminobenzoic acid. Cyclic oligomers of diamines and dicarboxylic acids are not mentioned. T. L. Guggenheim, et al., Polymer Prepr., vol. 30, p. 138-139 (1989) report the attempted synthesis of the cyclic oligomer of m-phenylene isophthalamide by a high dilution reaction procedure, but they report no "appreciable amount of cyclic formation". Y. H. Kim, et al., Abstracts of the 35th IUPAC International Symposium on Macromolecules, University of Akron, Jul. 11-15, 1994, report the synthesis of a nitro-substituted cyclic oligomer of m-phenylene isophthalamide. Also reported is a metal salt complex of this cyclic oligomer. SUMMARY OF THE INVENTION This invention concerns a cyclic oligomer of the formula ##STR1## wherein: n is an integer ranging from 3 to 12; each of R.sup.1, R.sup.2, and R.sup.3 is independently hydrogen, halogen, hydrocarbyl containing 1 to 6 carbon atoms, or nitro; and each of R.sup.4, R.sup.5, and R.sup.6 is independently hydrogen, halogne, or hydrocarbyl containing 1 to 6 carbon atoms. This invention also concerns a complex between a cyclic oligomer of the formula ##STR2## and a metal chloride, wherein said metal is selected from the group consisting of calcium, barium, strontium and the transition metals, wherein: n is an integer ranging from 3 to 12; each of R.sup.1, R.sup.2, and R.sup.3 is independently hydrogen, halogen, hydrocarbyl containing 1 to 6 carbon atoms, or nitro; and each of R.sup.4, R.sup.5, and R.sup.6 is indendently hydrogen, halogen, or hydrocarbyl containing 1 to 6 carbon atoms. Also described herein is a process for the preparation of a cyclic oligomer, comprising contacting a first solution of a compound of the formula ##STR3## with a second solution of a compound of the formula ##STR4## wherein X is halogen; each of R.sup.1, R.sup.2, and R.sup.3 is independently hydrogen, halogen, hydrocarbyl containing 1 to 6 carbon atoms, or nitro; and each of R.sup.4, R.sup.5, and R.sup.6 is hydrogen, halogen, or hydrocarbyl containing 1 to 6 carbon atoms; wherein said contacting is done with agitation or mixing; the concentration of (II) in said first solution is about 0.1 molar or less; and the concentration of (III) in said second solution is about 0.1 molar or less. This invention also includes a process for the polymerization of a cyclic oligomer of m-phenylene isophthalamide, comprising contacting said cyclic oligomer with a base which is capable of removing an amido hydrogen atom from said cyclic oligomer. Suitably, the polymerization is carried out at a temperature of about 150.degree. C. to about 380.degree. C. in an inert liquid medium. Also disclosed herein is a polymer, which is a reaction product of a compound of the formula ##STR5## with a compound of the formula R.sup.13 (COX).sub.2 (V) wherein each R.sup.7, R.sup.8, R.sup.9, R.sup.10, R.sup.11, and R.sup.12 is independently amino or hydrogen; R.sup.13 is hydrocarbylene, X is halogen, provided that: a total of at least two of R.sup.7, R.sup.8, R.sup.9, R.sup.10, R.sup.11, and R.sup.12 are amino; the molar ratio of (V):(IV) is at least about 1:1; and the molar ratio of (V):(IV) is such that number of equivalents of COX groups in the reaction does not substantially exceed the number of amino groups. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is the structure of the CaCl.sub.2 complex of compound (I) above, wherein n=3 and R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are all hydrogen, based on X-ray crystallography (see Example 13 below). DETAILS OF THE INVENTION Disclosed herein are cyclic oligomers of the formula (I) above, which are cyclic oligomers, analogous to a polyamide, comprising substituted or unsubstituted m-phenylene isophthalamide. In compounds of formula (I), it is preferred that R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are all hydrogen. In another preferred embodiment of formula (I), the groups R.sup.1, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are all hydrogen, and R.sup.2 is nitro. It is also preferred that n is 3 (cyclic trimer). By hydrocarbyl herein is meant a univalent radical containing only carbon and hydrogen, preferably containing 1 to 6 carbon atoms, more preferably 1 to 4. These cyclic oligomers form complexes with certain metal salts. Such a complex may be formed by mixing a cyclic oligomer with a solution of the metal salt in a solvent or, alternatively, by forming the cyclic oligomer in the presence of the metal salt. The complex may be converted back to the (simple) cyclic oligomer and free metal salt by washing the complex with a solvent for the salt such as water. Mixtures of solvents may also be used, and mixtures of the above mentioned and similar solvents with water are preferred. The preferred complexes have the same formula for the cyclic oligomer as in the preferred cyclic oligomers by themselves (described above). Preferred metal salts are calcium chloride and ferric chloride. FIG. 1 shows the structure of a complex wherein n is 3, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are all hydrogen, and the metal salt is calcium chloride. The cyclic oligomers described herein may be made by high dilution reaction techniques known in the art as being particularly useful for producing cyclic compounds. See, for instance, L. F. Feiser, et al., Organic Chemistry, 3rd Ed., Reinhold Publishing Corp. New York, 1956, p. 318-320, which is hereby incorporated by reference. Dilute solutions of the two reactants (II) and (III) are mixed with good agitation, preferably at rates such that, at any given time, the concentration of (II) and (III) are each relatively low and the molar amounts of (II) and (III) in the solution are approximately equal. This will usually mean that the molar rate of addition of (II) and (III) to the process will be approximately equal. Solutions of (II) and (III) may be simultaneously added to a portion of the solvent with agitation, as illustratd by Examples 1-8 below. In another method, dilute solutions of (II) and (III) are directly mixed together with good agitation in an impinging flow mixing tee. Preferred solvents for the synthesis of the cyclic oligomers are those normally used for the synthesis of aramids, such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and hexamethylphosphoramide. Especially preferred are N-methylpyrrolidone and N,N-dimethylacetamide. The concentration of (II) and (III) in the first and second solutions respectively are each about 0.1 molar or less, preferably each about 0.01 molar or less. The temperature at which the process is carried out is not critical, a range of -5.degree. C. to about +50.degree. C. being convenient, preferably about -5.degree. C. to about +5.degree. C. According to the present process, it is preferred that R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are all hydrogen, or that R.sup.1, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are all hydrogen and R.sup.2 is nitro. In the process for forming the cyclic oligomers comprising m-phenylene isophthalamide, it has been found helpful to include in the solution in which the cyclic oligomer is forming a metal salt, as defined above. It is believed that the metal salt acts something like a "template" to increase the yield of cyclic oligomer. The salts which are used and preferred above for the metal salt complex of the cyclic oligomers are also useful and preferred in the process for the synthesis of the cyclic oligomers. The initial products, when these salts are present, are the salt complexes of the cyclic oligomers. As described above, they are readily converted to the cyclic oligomers themselves. The cyclic oligomers may be converted to the corresponding linear polymers by contacting the cyclic oligomers with a base capable of removing an amido hydrogen atom from the cyclic oligomer (the "first polymerization"). By this is meant that the base is basic enough to remove the hydrogen atom from the group --CO--NH-- which is present in the cyclic oligomer. Suitable bases include, for example, those having a hydride anion, as in sodium hydride, an amide anion, as in potassium or sodium amide, or an alkoxide, as in sodium methoxide. Alkali metal hydride and alkoxides are preferred bases. Only a catalytic amount of base need be used, about 15 molar percent or less based on the amount of cyclic oligomer present. During polymerization, it is preferred that R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are all hydrogen. In other words, the cyclic oligomer of m-phenylene isophthalamide is polymerized to form poly(m-phenylene isophthalamide). The first polymerization is carried out at a temperature of about 150 to about 380.degree. C., preferably about 150 to about 300.degree. C. It is suitably carried out in an inert liquid medium, which may or may not dissolve the cyclic oligomer and/or basic catalyst. Suitable inert liquid media include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, diphenyl sulfone, tetramethylenesulfone, and the like, wherein N-methylpyrrolidone and diphenyl sulfone are preferred. In order to avoid undesired side reactions, particularly of the base present, it is preferred that the process be carried out under an inert gas such as nitrogen or argon, and that the starting materials be reasonably dry. The product of the first polymerization, poly(m-phenylene isophthalamide), and its substituted analogs, are aramids which are useful for making fire resistant garments, particularly of use to firefighters. The cyclic oligomer may also be used to sequester certain metal salts or to remove them from waste streams. The cyclic oligomers are also useful as a high temperature additive for polymers. The metal salt complexes may be used as source of the metal salts, as when used for melting ice. In a second polymerization, an amino functional cyclic amide (IV), as defined above, is reacted with a difunctional acyl halide (V), as also defined above. When only two of R.sup.7, R.sup.8, R.sup.9, R.sup.10, R.sup.11, and R.sup.12 are amino, a linear polyamide is produced wherein the cyclic amide moieties derived from (IV) alternates with the moieties derived from (V). When more than two of R.sup.7, R.sup.8, R.sup.9, R.sup.10, R.sup.11, and R.sup.12 are amino, a crosslinked thermoset polymer will be produced if most of the amino groups are reacted with acyl halide groups. In the second polymerization, it is preferred that R.sup.7, R.sup.9, and R.sup.11, the substitutents on the ring derived from the diacid, are amino, and/or all of R.sup.8, R.sup.10, and R.sup.12, the substituents on the ring derived from the diamine, are all hydrogen. It is also prefered that X is chlorine and that a sufficient amount of (V) is added so that at least 75 mole percent of the amino groups present are reacted. If a thermoplastic, the polymer may be used as a molding resin. If it is not thermoplastic and/or crosslinked, it may be used as a thermoset resin. In both cases, parts for electrical equipment, especially useful at high temperature, may be made. In the Examples, the following abbreviations are used: DMAc--N,N-dimethylacetamide DMF--N,N-dimethylformamide I--isophthalic ICl--isophthaloyl chloride MPD--m-phenylenediamine NMP--N-methylpyrrolidone NMR--nuclear magnetic resonance spectroscopy |
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| PATENT PHOTOCOPY | Available on request |
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