Activated aromatic dihalides

A consequence of the reaction is that it is possible to produce a range of polymers by reacting bisphenates with appropriately activated aromatic dihalides. In the case when the dihalide is activated by the presence of a sulphone —SO,— group the polymers may be referred to as polysulphones. The Amoco materials are prepared in this way. 

Diphenol/thiophenol is one of the most important polymer precursors for synthesis of poly(aryl ethers) or poly-(aryl sulfides) in displacement polymerizations. Commonly used bisphenols are 4,4 -isopropylidene diphenol or bisphenol-A (BPA) due to their low price and easy availability. Other commercial bisphenols have also been reported [7,24,25]. Recently, synthesis of poly(aryl ethers) by the reaction of new bisphenol monomers with activated aromatic dihalides has been reported. The structures of the polymer precursors are described in Table 2. Poly(aryl ether phenylquinoxalines) have been synthesized by Connell et al. [26], by the reaction of bisphenols containing a preformed quinoxaline ring with... 

Recently, the pyrazole group containing bisphenols have been synthesized from activated aromatic dihalides and 3,5-bis (4-hydroxy phenyl)-4-phenyl pyrazole or 3,5-bis(4-hydroxy phenyl)-1,4-diphenyl pyrazole. A novel synthesis of imido aryl containing bisphenols has been reported [32]. N-substituted l,4-bis(4-hydroxy phenyl)-2,3-naphthalimides were prepared from phenolphthalein and copolymerized with aromatic sulfone or ketone difluorides to obtain the poly(imidoaryl ether) sulfones/ ketones. 

Another (family of linear aromatic polymers is the polysulfones. They are tough, high-temperature-resistant engineering thermoplastics. Polysulfones may be synthesized by the nucleophihc substitution of alkali salts of biphenates with activated aromatic dihalides. A typical example is the preparation of bisphenol A polysulfone (21) from the reaction of disodium salt of bisphenol A with dichlorodiphenyl sulfone ... 

PTs can be prepared by involving the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)-1,2,4-triazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents, such as sulfolane or diphenyl sulfone, using alkaU metal bases, such as potassium carbonate, at elevated temperatures under nitrogen. 

It is economically and synthetically more favorable than other routes and allows a facile variation of the chemical structure, because a large variety of activated aromatic dihalides are available. The polymers are useful as composite matrix resins for aircraft and dielectric interlayers in electronic devices. ... 

Some current preparations of poly(arylene ether)s are carried out by nucleophilic displacements of activated aromatic dihalides or dinitro groups by alkali metal bisphenates. The reactions take place in polar aprotic solvents. The glass transition temperatures, tensile strengths, and tensile moduli of these materials tend to increase when heterocyclic units are incorporated into the backbones. Poly(arylene ether)s containing imide, phenylquinoxaline, imidazoles, pyrazoles, l,3,4-oxadiazoles, benzoxazoles, and benzimidazoles groups were prepared. 

PTs can be prepared by involving the aromatic nucleophilic displacement reaction of di(hydro-xyphenyl)-1,2,4-triazole monomers with activated aromatic dihalides or activated aromatic dinitro... 

Nucleophilic displacement chemistry involving aromatic dihalides and bisphenois, represented the first means by which high molecular weight aromatic polyethers could be produced. This technology has since been the basis for all commercial processes developed for this family of Engineering Polymers. The preparative method involves the nucleophilic polycondensation of a bispheno salt with an activated aromatic dihalide in an aprotic solvent. Further investigations have shown that the method has a very wide scope and that it can be applied to the preparation of a host of aromatic poly (sulfone ethers), poly (ketone ethers) and other related polyethers. 

The synthesis of polysulfones (PSF) can be performed by two main routes a polysulfonylation process, which is a classical electrophilic aromatic substitution [1], or a polyether synthesis, which is a nucleophilic substitution of activated aromatic dihalides [2,3]. 

High performance polymer films and coating materials are increasing being required by the electronics industry for use as interlayer dielectrics and as passivation layers. Aromatic polyimides are general the polymers of choice for these applications because of their unique combination of chemical, physical, and mechanical properties (i). Another class of polymers which have been investigated for these applications are the po arylene ether)s that can be prepared by the nucleophilic displacement of activated aromatic dihalides alkali metal bisphenoxides. Heterocycles such as benzoxazoles (2), imidazoles (5), phenylquinoxalines (.4), and 1,2,4-triazoles (5) have been incorporated within poly(arylene ethers) utilizing this thetic procedure. 

The synthesis of poly(arylene ether oxadiazoles) firom bis(hydroxyphenyl oxadiazoles) and commercially available activated aromatic dihalides has recently been reported (5). As part of an effort to develop high performance, high temperature resistant polymers for microelectronic applications, we have prepared a series of poly(arylene ether-l,3,4-oxadiazoles) and diaracterized their thermal, mechanical, and electrical properties. The po arylene ether-l A oxadiazoles) reported herein were prepared by the reaction of a bisphenol with the bis(4-fluorophenyl)-l,3,4-oxadiazoles, 1 and 3, using potassium carbonate in N,N-dimethylacetamide. 

Yang J, Gibson HW (1999) A polyketone synthesis involving nucleophilic substitution via carbanions derived from bis(a-aminonitrile)s. 5. A new, well-controlled route to long bisphenol and activated aromatic dihalide monomers. Macromolecules 32 8740-8746... 

Imai Y, Ishikawa H, Park KH, Kakimoto M (1997) A facile cesium iluraide-mediated synthesis of aromatic polyethers from bisphenols and activated aromatic dihalides. J Polym Sci Part A Polym Chem 35 2055-2061... 

The reaction of aryltellurium trichlorides 116 with activated aromatics 117 gives the corresponding diaryltellurium dihalides 118, which by reduction give the diaryl tellurides 119.5 11 12 55... 

Unsymmetrical diorganyltellurium dihalides are formed upon condensation of aryltellurium trichlorides with activated aromatic compounds and with ketones. The addition of the trichloride across carbon-carbon double bonds in alkenes, as well as the reaction with aryl(trimethyl)silane, hexaphenyldilead, and aryhnercury chlorides leads to the transfer of the aryl group to the tellurium atom. 

Various types of condensation polymers such as aromatic polysulfonates and polysulfides, aromatic polyethers, aliphatic and aromatic polysulfides, and carbon-carbon chain polymers of high molecular weights by the phase-transfer catalyzed polycondensation fi-om combinations of aromatic disulfonyl chlorides, phosphonic dichlorides, activated aromatic dichlorides, and aliphatic dihalides, withbisphenol, aliphatic and aromatic dithiols, and active ethylene compounds. The two-phase polycondensation was generally carried out in a water-immiscible organic solvent-aqueous alkaline solution system at room temperature. The method of polycondensation offers a highly versatile and convenient synthetic method for a variety of condensation polymers. 

In 1967, condensation polymerizations of alkali bisphenates with negatively substituted aromatic dihalides has been reported as part of a general study on the synthesis of polysulfones and polyethers (8). In the reaction, ether bonds are formed through the nucleophilic substitution of the aromatic dihalides. This reaction is fast and relatively free of side reactions in comparison with the Friedel-Crafts process. Figure 3.1 demonstrates this condensation reaction. In general, sodium or potassium bisphenates and difluoride substituted aromatic monomers were used. The dilithium, calcium, or magnesium salts are insoluble in DMSO and therefore cannot be used. The reported order of reactivity in activated aromatic halides is usually F Cl Br I or F Cl > Br > I. The difluorides are found to be more reactive than the corresponding dichlorides. 

This reaction is accompanied by the separation of hydrogen halide, so that an acid acceptor is needed to catalize the reaction, which is carried out in polar solvents at high temperature [115]. Aromatic dihalides are not suitable reactants for this reaction, unless activated dihaloaromatic monomers are used [116]. 

Aryl tellurium trichlorides and tribromides condense with methoxybenzene4,5, 1,3-dihydroxybenzene, and dimethylaniline6 to give unsymmetrical diaryl tellurium dihalides. The condensations occur with the hydrogen atom in the para-position to the activating group in the aromatic compound. Aryl tellurium triiodides did not react6. 

Several different approaches to the construction of poly(arylene-carborane)s were initially considered (Scheme 1). These included (i) nucleophilic polycondensation between a bis-phenol and an activated, carborane-based dihalide in the presence of base, a reaction used for the synthesis of commercial polyetherketones and polyethersulfones,4 (ii) electrophilic polycondensation between an aromatic diacid and a carborane-based diarylether in the presence of a strong-acid catalyst,5 and (iii) direct, homogeneously-catalysed coupling of a carborane-based dihalide.6 However,... 

Hilborn et al. demonstrated the synthesis of PBOs (Figure 5.29) by polymerization of bis(fluorophenyl benzoxazoles) with bisphenols. This polymerization was based on the activation of the fluoro group toward nucleophilic aromatic substitution by the oxazole component of the benzoxazole heterocyclic [51]. The TgS of the poly(arylene ether benzoxazoles) ranged from 213 to 303 °C, depending on the bisphenol and activated dihalide used in the synthesis. Generally, the TgS increased with the bulkiness of the bisphenol used. The polymers containing the >C(CF3)2 unit in both the benzoxazole and the bisphenol moiety in the monomers showed higher solubility (NMP) compared to the other PBOs. The physical properties of fluorinated poly(arylene ether benzoxazole) s are presented in Table 5.3. 

Intensive development of applied research activities in the field of lyotropic LC polymer systems was observed in the mid-1960s and 1970s, when novel families of aromatic polyamides were obtained. These polymers are usually prepared by the polycondensation of aromatic diacyl dihalide (HalOCAr COHal) with an aromatic diamine (H2NAr NH2) in solution, according to the reaction... 

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