| PATENT ASSIGNEE'S COUNTRY | USA |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 19.10.1999 |
| PATENT TITLE |
Quaternary bisphenolates, methods for their preparation, and uses thereof |
| PATENT ABSTRACT |
Quaternary salts having a double helix structure are prepared by the reaction of dihydroxyaromatic compound, preferably a bisphenol, with an alkali metal hydroxide and a quaternary salt, such as a tetraalkylammonium or hexaalkylguanidinium chloride. The quaternary salts and their alkaline hydrolysis products are useful as catalysts in various reactions, including imide formation from bisphenol salts and halo- or nitro-substituted phthalimides and redistribution and equilibration of polycarbonates. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | December 15, 1997 |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A method for preparing a polyether or intermediate therefor which comprises contacting, at a temperature in the range of about 100-250.degree. C., at least one alkali metal salt of a dihydroxyaromatic compound with at least one halo- or nitro- substituted aromatic compound in the presence of a catalytic amount of an alkaline hydrolysis product of a quarternary salt of a dihydroxyaromatic compound, the salt having the molecular formula H.sub.3 Q(OA.sup.1 O).sub.2, (I) wherein A.sup.1 is a divalent aromatic radical and Q is a monocationic carbon- and nitrogen- or phosphorous-containing moiety. 2. A method according to claim 1 wherein the dihydroxyaromatic compound is bisphenol A and the substituted aromatic compound is 4-nitro-N-methylphthalimide. 3. A method according to claim 1 wherein the dihydroxyaromatic compound is bisphenol A and the substituted aromatic compound is a chloro- or nitro-substituted bis(etherphthalimide). 4. A method of preparing a polycarbonate which comprises equilibrating a reaction system comprising a linear or branched polycarbonate in the presence of a catalytic amount of a quaternary salt of a dihydroxyaromatic compound, the salt having the molecular formula H.sub.3 Q(OA.sup.1 O).sub.2, (I) wherein A.sup.1 is a divalent aromatic radical and Q is a monocationic carbon- and nitrogen- or phosphorous-containing moiety. 5. A method according to claim 4 wherein the reaction system also contains a polyphenolic compound as a branching agent. 6. A method according to claim 4 wherein the polycarbonate is a bisphenol A polycarbonate. 7. A method of preparing a polycarbonate which comprises contacting at least one dihydroxyaromatic compound with a diaryl carbonate In the melt in the presence of a catalytic amount of a quaternary salt of a dihydroxyaromatic compound, the salt having the molecular formula H.sub.3 Q(OA.sup.1 O).sub.2, (I) wherein A.sup.1 is a divalent aromatic radical and Q is a monocationic carbon- and nitrogen- or phosphorous-containing moiety. 8. A method according to claim 7 wherein the polycarbonate is a bisphenol A polycarbonate. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
BACKGROUND OF THE INVENTION This invention relates to bisphenol chemistry, and more particularly to the preparation of a genus of catalysts containing bisphenol moieties. The use of tetraalkylammonium and hexaalkylguanidinium salts as phase transfer catalysts in the preparation of various polymers is known. In particular, U.S. Pat. Nos. 4,273,712 and 5,132,423 disclose the reaction of bisphenol salts with halo- or nitro-substituted phthalimides in an organic medium to produce bisimides which, upon conversion to dianhydrides and reaction with diamines, form polyetherimides. U.S. Pat. Nos. 3,787,364, 3,838,097, 3,847,869 and 5,229,482 disclose a similarly phase transfer catalyzed reaction of bisphenol salts with halo- or nitro-substituted bis(phthalimido) derivatives of aromatic diamines or with similar compounds, resulting in the direct formation of polyetherimides and other polyether polymers. The phase transfer catalysts employed according to U.S. Pat. Nos. 5,132,423 and 5,229,482 are guanidinium and especially hexaalkylguanidinium salts; in the other patents, tetraalkylammonium salts are disclosed as suitable catalysts. The hexaalkylguanidinium salts which are easiest to prepare are the chlorides, but they are hygroscopic. It is burdensome to store them in anhydrous form and subsequently dry them or to isolate them in anhydrous form, which is essential for the polyetherimide-forming reactions. One of the by-products in the reaction of bisphenol salts with nitro-substituted compounds is an alkali metal nitrite, typically sodium nitrite. It is ordinarily removed by washing the organic reaction system with water. It would be desirable to recover the sodium nitrite and sell it for further use. However, chloride levels in by-product nitrite salts are high, which can cause corrosion of metal reaction vessels in contact therewith. In addition, commercial applicability requires that sodium nitrite contain a very low chloride level, typically no greater than 100 ppm by weight, which is difficult or impossible to attain with the use of a hexaalkylguanidinium chloride, for example, as a phase transfer catalyst. For these reasons and others, it is desirable to prepare non-hygroscopic hexaalkylguanidinium and tetraalkylammonium salts, as well as salts containing an anion other than chloride. SUMMARY OF THE INVENTION The present invention is based on the discovery of a novel series of hydrogen-bonded tetraalkylammonium, tetraalkylphosphonium and hexaalkylguanidinium bisphenolates. These compounds are easily synthesized or may be obtained from waste streams generated in various stages of polyetherimide production. They can be obtained in high yield by certain adjustments in the treatment of the waste stream. The quaternary bisphenolates have high oxidative and thermal stability and are non-hygroscopic. Therefore, they are easily stored. They are convertible to compounds effective as phase transfer catalysts in the production of polyetherimides and similar polymers. They are also capable of use in other processes involving the recycle of such materials as hexaalkylguanidinium salts and bisphenols. Moreover, they themselves are active as catalysts in the production of other polymers including linear and branched polycarbonates. In one of its aspects, the invention includes quaternary salts of dihydroxyaromatic compounds, said salts having the molecular formula H.sub.3 Q(OA.sup.1 O).sub.2, (I) wherein A.sup.1 is a divalent aromatic radical and Q is a monocationic carbon- and nitrogen- or phosphorus-containing moiety. Another aspect of the invention is a method for preparing a quaternary salt of the type represented by formula I which comprises contacting a dihydroxyaromatic compound of the formula (HO).sub.2 A.sup.1 with an alkali metal hydroxide and a quaternary salt of the formula Q.sup.+ X.sup.-, wherein A.sup.1, Q and Y are as previously defined and X is halide. Another aspect is a method for preparing a polyether or intermediate therefor which comprises contacting, at a temperature in the range of about 100-250.degree. C., at least one alkali metal salt of a dihydroxyaromatic compound with at least one halo- or nitro-substituted aromatic compound in the presence of a catalytic amount of an alkaline hydrolysis product of said quaternary salt of the type represented by formula I. A further aspect is a method of preparing a branched polycarbonate which comprises equilibrating a reaction system comprising a linear or branched polycarbonate of a different molecular weight from the desired one in the presence of a polyphenolic compound and a catalytic amount of said quaternary salt of the type represented by formula I. Still another aspect is a method of preparing a polycarbonate which comprises contacting at least one dihydroxyaromatic compound with a diaryl carbonate in the melt in the presence of a catalytic amount of said quaternary salt of the type represented by formula I. DETAILED DESCRIPTION PREFERRED EMBODIMENTS The Q radical in the quaternary salts of formula I is a monocationic carbon- and nitrogen- or phosphorus-containing moiety; i.e., a moiety having a single positive charge. It may be a tetraalkylammonium or tetraalkylphosphonium moiety wherein the alkyl groups contain 2-12 and preferably 2-6 carbon atoms, as illustrated by tetraethylammonium, tetra-n-butylammonium, tetra-n-butylphosphonium and diethyldi-n-butylammonium. Preferably, however, it is a hexaalkylguanidinium moiety such as hexaethylguanidinium, hexa-n-butylguanidinium or tetraethyldi-n-butylguanidinium. The atom content of the Q radical is preferably 9-40 atoms including carbon and nitrogen or phosphorus atoms; its size is governed by the fact that the tetraethylammonium and tetraethylphosphonium cations contain 8 carbon atoms and one nitrogen or phosphorus atom for a total of 9, while the hexahexylguanidinium cation contains 37 carbon atoms and 3 nitrogen atoms for a total of 40. The A.sup.1 radical may be a monocyclic radical; i.e., an unsubstituted or substituted m- or p-phenylene radical. Most often, however, it has the formula --A.sup.2 --Y--A.sup.2 --, (II) wherein A.sup.2 is unsubstituted p-phenylene and Y is a single bond or a bridging radical wherein 1-2 atoms separate the A.sup.2 values; i.e., A.sup.1 is a bisphenol-derived moiety. The preferred moieties of this type are those in which A.sup.2 is p-phenylene and Y may be any bridging radical in which one or two atoms separate the two A.sup.2 values. Illustrative Y radicals include methylene, ethylene, isopropylidene, 2,2-dichloroethylidene, oxygen and sulfur. It is also possible for Y to be a single bond, as is the case with 4,4'-biphenol. The preferred Y value is isopropylidene, which is present when the bisphenol employed as described hereinafter is 2,2-bis(4-hydroxyphenyl)propane; i.e., bisphenol A. By reason of the strong preference herein for compounds in which A.sup.1 has formula II, the quaternary salts of this invention are frequently designated "quaternary bisphenolates" hereinafter. It should be understood, however, that quaternary salts wherein A.sup.1 is monocyclic may be substituted for quaternary bisphenolates where appropriate. The quaternary salts of the invention may be prepared by the reaction of a dihydroxyaromatic compound of the formula (HO).sub.2 A.sup.1 with an alkali metal hydroxide and a quaternary salt of the formula Q.sup.+ X.sup.-. The X value in the quaternary salt is halide, preferably bromide or chloride and most preferably chloride. Typical reaction temperatures are in the range of about 10-125.degree. and preferably about 10-50.degree. C. An inert atmosphere such as nitrogen or argon may be employed. In a preferred embodiment of the invention, the reaction takes place in an aqueous medium, most often also containing a C.sub.1-3 alkanol and preferably methanol. The quaternary bisphenolate is usually insoluble in water but soluble in the alkanol, and often precipitates spontaneously; if not, it can be precipitated by addition of water. It is generally found convenient to initially form an alcoholic mixture of bisphenol and alkali metal hydroxide, whereupon the bisphenol dissolves as the alkali metal salt, and to add thereto an aqueous-alcoholic solution of the quaternary salt. Another alternative is to combine the bisphenol and quaternary salt and gradually add aqueous alkali metal hydroxide solution thereto. In the water-alkanol embodiment, ambient temperatures in the range of about 20-30.degree. C. are generally preferred. In still another procedure, a non-polar organic solvent such as toluene is employed. An aqueous alkaline solution of the quaternary salt is added gradually to a combination of the bisphenol and refluxing solvent. The product precipitates out and can be purified by washing with water. Further purification of product obtained by any of these methods can be achieved by recrystallization, most often from an alkanol and preferably methanol. Reactant proportions are not critical in the method for preparing the quaternary bisphenolates. This is apparent from the fact that their formation was initially discovered in mixtures comprising the non-stoichiometric proportions of 2 moles of alkali metal hydroxide, 2 moles of hexaalkylguanidinium chloride and 1 mole of bisphenol. For optimum yield, however, a bisphenol:quaternary salt:alkali metal hydroxide molar ratio of 2:1:0.5-1.5 and especially 2:1:1 is preferred. X-ray diffraction analysis of the product obtained from bisphenol A, hexaethylguanidinium chloride and sodium hydroxide has shown it to have the molecular structure of a double helix of anionic bisphenol A moieties interconnected via hydrogen bonds between two oxygen atoms through the three protons. The hexaethylguanidinium cationic moieties are ionically associated with the anionic double helix and most often are located within the pockets formed by the hydrogen bonds. A similar structure is postulated for other quaternary bisphenolates of the invention. The preparation of the quaternary bisphenolates of this invention is illustrated by the following examples. All percentages are by weight. "Catalyst solution" in these examples is, unless otherwise indicated, an aqueous solution of 28.54% hexaethylguanidinium chloride and 10.09% sodium chloride. |
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