Phenylene general synthesis

This paper reviews some of our work on general methods for the synthesis of polyaromatics containing either terminal or pendant styrene groups and their thermal polymerization. The examples provided in this paper refer to an aromatic polyether sulfone (PSU) and poly-(2,6-dimethy1-1,4-phenylene oxide) (PPO). 

It is important to clarify whether catalyst-transfer condensation polymerization is specific to polythiophene, or whether it is generally applicable to the synthesis of well-defined it-conjugated polymers. We investigated the synthesis of poly(p-phenylene), to see whether a monomer 28 containing no heteroatom in the aromatic ring would undergo catalyst-transfer polymerization. However, all polymers obtained in the polymerization with Ni(dppp)Cl2, Ni(dppe)Cl2, or Ni(dppf)Cl2 possessed low molecular weights and broad polydispersities. Nevertheless, we found that LiCl was necessary for opti-... 

Scheme 5.6 The general principle for the synthesis of catenanes (or rotaxanes) based on cyclobis(paraquat-p-phenylene) and crown ethers containing hydroquinone units. The dipyridyl units are alternatingly stacked with two hydroquinones because of n-n interactions which direct the ring-closure toward the formation of a catenane.

Coupling carbonyl compounds with aromatic amines bearing amino, hydroxy, or thiol groups in o -positions is known to be a general method for the synthesis of 1,3-benzazoles, with the intermediate formation of the respective 2,3-dihydro derivatives. No heterocyclization occurs, however, in the reaction of o-phenylene-diamines or o-aminophenols with /i-quinones. In these cases, the reaction stops at the stage of formation of the deeply colored quinoneimine 105 which is similar to that obtained by the previously studied reaction of a variety of / -substituted anilines with derivatives of p -bcn/oquinonc.6 Compounds 10 do not undergo cyclization under heating or irradiation of its solution (Scheme 4). 

Bis[(]V-vinylpyrrol-2-yl)]diphenyloxide (85), 4,4 -bis(pyrrol-2-yl) diphenylsulfide (86), 4-(pyrrol-2-yl)-4 -[(N-vinylpyrrol-2-yl)]diphe-nylsulfide (87) and 4,4 -bis[(N-vinylpyrrol-2-yl)]diphenylsulfide (88) were synthesized in a one-pot procedure from oximes of the corresponding diacetylphenylenoxide 89 and -sulfide 90 through reaction with acetylene (MOH-DMSO, M = Li, K), thus illustrating the applicability and general character of the synthesis of diverse dipyrrole-phenylene assemblies and their N-vinyl derivatives (Equation (23)) (05T7756). 

Conjugated polymers like poly(l,4-phenylene-vinylene), PPV, or more generally Poly(arylene-vinylenes), PAVs have evoked considerable interest as electrically conductive and nonlinear optical materials. More recently, electroluminescence properties of PPV have attracted substantial attention, since it was first reported in 1990. Direct synthesis of PPV has been limited by its insolubility. Hence, the most commonly used routes are based on soluble polymer precursors or soluble conjugated precursors. The latter process is also commonly referred to as the sulfonium-based polyelectrolyte precursor route. PPV thin films from these solution-based routes, however, have problems related to contamination by solvents and oxidative defects in the polymer. C VP is an alternate method for the deposition of high quality thin films of PPV. Reported first by Iwatsuki et al., it was investigated for electroluminescence applications by Staring et al. ... 

In the past, little work has been directed to the synthesis of new conjugated polymers, since the activities of the chemists have been concentrated on improving the synthetic accessability of already known conjugated polymers and on establishing structure-property relationships. Remarkable exceptions to this general statement are poly(phenylene sulfide-phenyleneamine) (PPSA) 139 and poly(phenylene sulfide-phenyleneamine-phenyleneamine) (PPSAA) 140 recently synthesized by Mullen et al. (see chart 21) [198]. The polymers represent two... 

Catalysts are also required in many stepwise polymerizations. For example, reaction of polycarboxylic acids and polyols (Reaction 7) is catalyzed by acids ester interchange, by metal compounds such as titanium alkoxides. On the other hand, polyurea synthesis (Reaction 6) generally does not require a catalyst. Metallic compounds are also useful in oxidative polymerization of phenols to give poly(phenylene oxides), illustrated in Reaction 14. 

The newest engineering thermoplastic is a polyetherimide that was formally announced by General Electric Company in 1982 (16). This amorphous polymer is designated Ultem resin and resulted from the research work of a team headed by J. G. Wirth in the early 1970s (9). The early laboratory process involved a costly and difficult synthesis. Further development resulted in a number of breakthroughs that led to a simplified, cost-effective production process. The final step of the process involves the imidization of a diacid anhydride with m-phenylene diamine (Figure 13). 

Poly(p-phenylene vinylene) (PPV) is a conjugated polymer, which becomes conductive by the addition of electron donors or acceptors [114, 115], Several methods have been reported for the synthesis of PPV [3, 4, 6], Direct chemical polymerization, which was used in the first attempt of synthesizing PPV, gave a product in the form of an insoluble powder that limited the use of the polymer in many applications [116], The most popular method for the preparation of PPV is base-induced polymerization of sul-fonium salt monomer in aqueous solution [114-118], In this method, PPV films are obtained from the precursor polymer after thermal elimination of the sulfonium groups. PPV has also been prepared electrochemically by reducing p-xylene-bis-(triphenylphosphonium). Two approaches are generally used for the synthesis of PPVs the Wessling... 

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