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US5169929.Pdf |||||||||||| USOO5169929A United States Patent (19) 11) Patent Number: 5,169,929 Tour et al. 45 Date of Patent: Dec. 8, 1992 (54) LITHIUM/HMPA-PROMOTED SYNTHESIS Noren, et al. Macromolecular Reviews (1971) 5. pp. OF POLY(PHENYLENES) 386-431. Yamamoto, et al. Bulletin Che. Soc. of Japan (1978) 51. 75 Inventors: James M. Tour; Eric B. Stephens, (7) pp. 2091-2097. both of Columbia, S.C. Shacklette, et al. J. Chem. Soc., Chem. Commun. (1982) 73 Assignee: University of South Carolina, pp. 361-362. Columbia, S.C. Ivory, et al. J. Chem. Phys. (1979) 71. (3) pp. 1506-1507. Shacklette, et al. J. Chem. Phys. (1980) 73. (8) pp. 21 Appl. No.: 543,673 4098-4102. 22 Filed: Jun. 25, 1990 Kovacic, et al. J. Org. Chem. (1963) 28. pp. 968-972, 1864-1867. I51) Int. Cl. .............................................. CO8G 61/00 Kovacic, et al. J. Org. Chem. (1964) 29. pp. 100-104, 52 U.S.C. .................................................... 528/397 2416-2420. 58 Field of Search ......................................... 528/397 Kovacic et al. J. Org. Chem. (1966) 31. pp. 2467-2470. (56) References Cited Primary Examiner-John Kight, II U.S. PATENT DOCUMENTS Assistant Examiner-Terressa M. Mosley Attorney, Agent, or Firm-Brumbaugh, Graves, 4,576,688 3/1966 David .................................. 528/397 Donohue & Raymond OTHER PUBLICATIONS 57 ABSTRACT Kovacic, et al. Chem. Rev. (1987) 87, pp. 357-379. Poly(phenylene) that is substantially free of insoluble Elsenbaumer, et al. Handbook of Conducting Polymers material is prepared by the polymerization of a lithi (1986), T. A. Skotheime ed. pp. 213-263. oarylhalide compound in the presence of a polar aprotic Perlstein, Angew. Chem. Int. Ed. Engl. (1977) 16, pp. compound such as hexamethylphosphoramide, 519-534. N,N,N',N'-tetramethylethylenediamine or hexamethyl Kovacic, et al. J. Polymer Science (1966) Part A-1 4. phosphorous triamide. The preferred reaction involves pp. 5-28. the polymerization of 1-bromo-4-lithiobenzene in the Kovacic, et al. J. Polymer Science (1966) Part A-1 pp. presence of hexamethylphosphoramide. The 1-bromo 1445-1462, 4-lithiobenzene may be synthesized by reacting 1,4- Encyclopedia of Polymer Science & Technology dibromobenzene with t-butyllithium. These same types (1969), vol. 11 pp. 318-363, 380-389. of reactions can also be used to synthesis other benze Edwards, et al. J. Polymer Science (1955) XVI. pp. noid polymers. 589-598. Goldfinger J. Polymer Science (1949) IV. pp. 93-96. 10 Claims, No Drawings 5,169,929 1 2 Poly(phenylene) has been synthesized via the mono LITHIUM/HMPA-PROMOTED SYNTHESIS OF Grignard reagent of dibromobenzene. Yamamoto, et al., POLY(PHENYLENES) Bull. Chem. Soc. Jpn. 51, 2091, (1978). Coupling to form the polymer was achieved by the addition of a The invention of this application was supported by a 5 nickel(II) catalyst (presumably via reduction of the grant from the Office of Naval Research, Grant No.: nickel to nickel(O), oxidative addition, transmetallation, N00014-89-3062. The U.S. Government has a paid-up and reductive elimination to regenerate nickel(O) as the license in this invention and the right in limited circum active catalytic species). Degrees of polymerization are stances to require the patent owner to license others on estimated to be about 20 units. However, completely reasonable terms. 10 insoluble poly(phenylene) is obtained by this method, though most of it is para by IR analysis. The insolubility BACKGROUND OF THE INVENTION is probably due to extensive cross linking. An analogous This invention relates to unique compositions of solu method by Ullmann using copper metal has been de ble, conductive poly(phenylene) and to synthetic meth scribed for the synthesis of substituted poly(pheny ods useful in the synthesis of these compositions. 15 lenes); however, temperatures of 220-270° C. are nec Poly(phenylene)s, also known as polyphenyls, poly essary, and the substituted poly(phenylenes) produced benzenes or oligobenzenes, are linear polymers formed have limited conductivity due to nonplanarity of the from substituted or unsubstituted benzene subunits. Of aryl rings. Claesson, et al., Makromol. Chem 7 46 particular interest among these compounds are parapo (1951). ly(phenylene)s which have been found to have conduc 20 Finally, para-poly(phenylene) has been synthesized tivities following oxidation or reduction by known by (1) bacterial oxidation of benzene and derivatization chemical, electrochemical, electronic or photonic to form 1,2-diacetoxy-3,5-cyclohexadiene, (2) radical means, comparable to metallic materials, i.e. greater polymerization, and (3) pyrolysis at 140-240° C. to than 100 Olcm. This property, combined with form parapoly(phenylene). The intermediate is soluble other physical and mechanical properties give such 25 materials tremendous potential for applications in the and films can be cast. Ballard, et al., J. Chem. Soc. electronics and photonics industry. A few, of numerous Chem. Commun. 954. However, upon pyrolysis, intrac applications are listed. table and insoluble material is formed. (1) New semiconductor materials could be obtained. The present invention solves the problem which was (2) Lightweight batteries could be obtained which 30 recognized by the art and produces a soluble poly(phe are of great importance to the military for naval and nylene) having a high conductivity. aerospace applications, and all mobile electric vehicles SUMMARY OF THE INVENTION which are becoming commercially feasible. (3) For X(3) nonlinear optical materials which will In accordance with the invention, high conductivity make-up the components of future photonic (rather 35 poly(phenylene) that is substantially free of insoluble than electronic) instrumentation. material is prepared by the polymerization of a lithi Known methods for the formation of poly(pheny oarylhalide compound in the presence of a polar aprotic lenes) involve (1) oxidative-cationic polymerization, (2) compound such as hexamethylphosphoramide, dehydrogenation of poly(1,3-cyclohexadiene), (3) metal N,N,N',N'-tetramethylethylenediamine or hexamethyl catalyzed coupling reactions and (4) Diels-Alder poly 40 phosphorous triamide. The preferred reaction involves merizations. In nearly all cases, however, the polymers the polymerization of 1-bromo-4-lithiobenzene in the are insoluble if they contain a majority of the para form presence of hexamethylphosphoramide. The 1-bromo which is required for highly conducting material. This 4-lithiobenzene may be synthesized by reacting 1,4- insoluble material limits the utility of the product poly(- dibromobenzene with t-butyllithium. These same types phenylene) because it cannot be cast into films or other 45 of reactions can also be used to synthesis other benze wise processed, other than by pressing, to form electri noid polymers. cal components. Thus, it would be highly desirable to DETAILED DESCRIPTION OF THE be able to produce a poly(phenylene) which was both INVENTION soluble, and hence processible, and high in conductiv ity. Prior to the present invention, however, no syn 50 Benzenoid polymers such as polyphenylene are syn thetic method could achieve both these goals. thesized in accordance with the invention by polymeri For example, Goldfinger, J. Polymer Sci 4, 93 (1949) zation of a lithioarylhalide in the presence of a polar and Edward et al., J. Polymer Sci 16, 589 (1955) re aprotic compound. As used herein, halo or halide refers ported the production of soluble, high molecular to fluorine, chlorine, bromine or iodine. weight poly(phenylene) by treatment of p-dichloroben 55 Suitable polar aprotic solvents are those which are Zene with liquid potassium-sodium alloy, KNa2, at 110 not decomposed by alkyllithium. Exemplary polar C. in dioxane for 24-48 hours. This material was never aprotic compounds include hexamethylphosphoramide, analyzed by IR or NMR techniques, nor was it ever i.e., (CH3)2N)3P(O), and related compounds such as used in conductivity studies. Later reports indicated N,N,N',N'-tetramethyethylenediamine (TMEDA) and that the severe reaction conditions caused the formation 60 hexamethylphosphorous triamide, ((CH3)2N)3P. Other of many reduced (aliphatic) rings. Because of these compounds will generally have a pKa of greater than 40 aliphatics, the material is not adequate for conductivity and no reactive functionalities. studies. Lithioarylhalides for use in the invention are conve Because of the recognition that aliphatics interfered niently generated in situ by reaction of an aryl dihalide with the desirable conductivity, methods have been 65 with at least one equivalent, and preferably at least two developed for the synthesis of aliphatic-free poly(phe equivalents of an alkyllithium that undergoes lithium/- nylenes). These invariably provided insoluble materials, halogen exchange, e.g., n-butyllithium, ethyllithium or however, and thus had unacceptable processability. t-butyllithium. 5,169,929 3 4 The method of the invention can be used to produce cool it to -78 C., and treat it with t-butyllithium. The para-poly(phenylene) that is substantially free of materi lithiated polymer was then quenched with water. als that are insoluble in solvents such as tetrahydrofuran (THF). Substantially free as used herein means that the level of insoluble materials present is so low that cast 5 films can be readily be prepared. In general this means H H(Br) l i. THF G that the poly(phenylene) contains less than about 5%. insoluble material. An exemplary reaction of a synthesis according to the H(Br) invention is shown in Eq. 1. 10 t-butyl bromide CH3 -BuLi (2 equiv) G B + CH-46 -Bu-Li () equiv remaining) + LiBr -)- Br etherial solvent CH 2 H Namaam1 HMPA H(Br) CH 3 CH3 )=CH, -- CH-H - LiBr PPP CH3 CH3 isobutylene isobutane Numama innocuous by-products In this equation, 1-lithio-4-bromobenzene (1) is formed by treatment of 1,4-dibromobenzene (2) with t-butylli thium. Two equivalents of t-butyllithium are used per anion generation. The first equivalent is for lithium 35 halogen exchange to form 1-lithio-4-bromobenzene, p t-butyl bromide, and lithium bromide.
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