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. 

Not surprisingly a number of other poly(aryl ethers) have been prepared from aromatic dihalides not containing sulphone links. For example, a number have been prepared from difluorobenzophenone and, in general, it is found that such materials have TgS about 30-40°C lower than the corresponding sulphone polyether. In fact it is generally found that the higher Tg values are obtained with the sulphone polyethers. 

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. 

The nucleophilic aromatic substitution reaction for the synthesis of poly(arylene ether ketone)s is similar to that of polysulfone, involving aromatic dihalides and aromatic diphenolates. Since carbonyl is a weaker electron-withdrawing group titan sulfonyl, in most cases, difluorides need to be used to afford high-molecular-weight polymers. Typically potassium carbonate is used as a base to avoid the... 

Polyetherketones and polyethersulfones, also referred to as polyketones and polysulfones, are synthesized by nucleophilic aromatic substitution between aromatic dihalides and bispheno-late salts [Cassidy, 1980 Clagett, 1986 Critchley et al., 1983 Harris and Johnson, 1989 Jayakannan and Ramakrishnan, 2001 Matsumura et al., 2001 May, 1988], This is shown in Eq. 2-206, where X is halogen and Y is C=0 or S02 ... 

Other reactions have been studied for synthesizing these polymers, including the electrophilic aromatic substitution of acyl and sulfonyl halides on aromatic reactants and the nickel-catalyzed aromatic coupling of aromatic dihalides [Yonezawa et al., 2000]. 

As ligands, phosphanes have proven to be useful (Table 7, No. 2-4). Poly(l,4-paraphenylene) is obtained on a preparative scale starting from aromatic dihalides (Table 7, No. 3, 4). The electrochemical generation and... 

An elegant synthesis method which is specific to sulfone polymers containing phenyl—phenyl linkages (such as PPSF) is the nickel-catalyzed coupling of aryl dihalides. The scheme for this synthesis involves a two-step process. First, an aromatic dihalide intermediate is formed which carries the backbone features of the desired polymer. This aromatic dihalide intermediate is then self-coupled in the presence of zero-valent nickel, triphenylphosphine, and excess zinc to form the biphenyl- or terphenyl-containing polymer. Application of this two-step scheme to PPSF can be depicted as follows ... 

The transition metal-catalysed coupling reaction of aryl halides with alkynes (alkynylation of aryl halides) is frequently also considered as a Heck reaction [68, 108-111], Polymers containing arylacetylene and diarylacetylene units in the backbone have been obtained by the self-coupling of ethynylaryl halides [scheme (3)] and the cross-coupling of aromatic dihalides with acetylene [scheme (6)] or diethynylbenzenes [scheme (7)] [112-121]. The majority of... 

Answer XII-c is a meta substituted aromatic dihalide (hi-chloroiodobcnzcnc). 

Recently, Johnson et al. (2) reported the synthesis of several aromatic polyethers by nucleophilic aromatic substitution reactions. These solution condensations take place between the diphenoxide salt of a bisphenol and an aromatic dihalide ... 

Lithium telluride, prepared from tellurium and lithium triethylborohydride in tetrahydro-furan, and sodium telluride, obtained from sodium and tellurium in a dipolar, aprotic solvent or from tellurium - and Rongahte in aqueous sodium hydroxide reacted with aliphatic and aromatic dihalides to produce polymeric organo tellurium compounds. 

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 ... 

The palladium-catalyzed cross-coupling of thiophenyl zinc reagents with aromatic dihalides was recently described (eq 5) [9]. The method was published in communication form but it did appear this could be a generally useful polymerization technique. 

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. 

As a corollary, it has been suggested that a useful way of identifying the products formed from the interaction of magnesium with aromatic dihalides is to treat the resulting mixture with iododimethylarsine and work up the resulting arsines (110). 

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... 

Similarly, aromatic polysulfonates and aromatic polyether were synthesized from the polycondensation of phenylphosphonic dichloride (IV) with bisphenol A (II) leading to a polyphosphonate (V), aromatic dihalides (VI) with alkaline salts of bisphenols (VII), under various phase transfer catalysis in two-phase system, i.e.. 

Nickel-catalyzed coupling of aromatic dihalides is a sjmthesis route that can be used to make sulfone polymers containing a phenyl-phenyl bond in their backbone, such as PPSF. This is a two-step sjmthesis that starts... 

Figure 50 2 1 complexes between stilbazoles and aromatic dihalides. 

Cathodic reduction of aromatic dihalides also undergoes to form conducting polymers on electrode. Moreover, a,a,a ,a -tetralffomo-/7-xylene can be electropolymerized to afford poly(p-phenylene-vinylene) by cathodic reaction [4]. 

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. 

In the late 1950 s a project was started to make other polyethers from bisphenois, especially bisphenol A, and alkylene dichlorides and aromatic dihalides. One goal was improved hydrolytic stability over the polyesters and polycarbonates known at that time. A second goal was high thermal stability with that of diphenyl ether being the ultimate target. 

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