Bromination of poly

An alternative synthesis of a thermally stable cyclopentadienyl functionalized polymer involved ring bromination of poly(oxy-2,6-diphenyl-l,4-phenylene), followed by lithiation with butyl lithium to produce an aryllithium polymer. Arylation of 2-norbornen-7-one with the metalated polymer yielded the corresponding 2-norbornen-7-ol derivative. Conversion of the 7-ol to 7-chloro followed by treatment with butyl lithium generated the benzyl anion which undergoes a retro Diels-Alder reaction with the evolution of ethylene to produce the desired aryl cyclopentadiene polymer, 6. 

Another exciting developing field is in material science. Chlorination and bromination of fullerenes18,19 and solid state bromination of poly acetylenes20,21 and of polybutadienes22 are typical examples. 

The bromination of poly-DCH is of interest because the degree of bromine uptake can be controlled, by choice of experimental conditions, between 3 and 8 Br atoms per polymer repeat unit and because a crystal-to-crystal transformation is observed. Scheme 1 summarizes the reactions of liquid bromine with poly-DCH. Interaction of poly-DCH crystals with dense vapors of bromine or cyanogen bromide for months did not lead to detectable weight gain. By contrast, DCH monomer (2a), which has a crystal structure similar to the polymer (6), readily reacts with bromine vapor to give an eunor-phous material which has gainbd ca 12 Br atoms per molecule. 

In the present study we have used this method to clarify the course of bromination of poly-DCH. Preliminary results have also been obtained on the chlorination and nitration of this polymer. Information about the chemical structure... 

There are many reports in the literature on the effects of chain conformation One example is radical bromination of poly(methyl styrene) with A-bromosuccinimide-benzoyl peroxide or... 

There are many report in the literature on the effects of chain conformation [19-25]. One example is radical bromination of poly(methyl styrene) [20] with Ai-bromosuccinimide-benzoyl peroxide or Br2-K2C03-light. NMR spectroscopy shows differences in reactivities of the methyl groups in the 3 and 4 positions on the benzene rings between isotactic and atactic polystyrenes [20]. 

A few indirect routes to substituted PAs are known [25]. The first involves bromination of poly(cyclopentadiene) followed by dehydrobromination and a rearrangement of the double bonds (Scheme XXVII) [146]. The resulting polymer is black and has a conductivity of 10 S/cm. A second method entails a tandem hydrolysis and enolization of a poly(cyclic anhydride) (Scheme XXVIII) [147]. Once again the polymer is black, and its conductivity is fairly low at 10 S/cm. 

Brominated Poly(Phenylene Oxide)s. II. Bromination of Poly(2,6-Dimethyl-l,4-Phenylene Oxide)... 

The preparation of bromine-containing polyphenylene oxides by modification of Price s polymerization of bromophenols was described in the preceding paper. An alternate route to these polymers is the direct bromination of polyphenylene oxides. The bromination of poly(2,6-dimethyl-l,4-phenylene oxide) to... 

Direct bromination of poly(2,6-dimethyl-l,4-phenylene oxide) (I) at high bromine concentrations introduced two bromine atoms onto the aryl rings of a majority of the repeating units tdiile at lower concentrations mainly monobromo units were formed. No... 

X-ray diffraction analysis of crystalline poly(schiff base)s and their low molecular models shows that the formation of molecular complexes is accompanied by an increase in interplanar distances and, in a number of cases, by complete amor-phization. Molecular complexes of poly(schiff base)s with Br2 decompose with time, because of the bromination of the donor components, forming C—Br bonds. Substitution of hydrogen by bromine in phenyl groups occurs only in cases in which these groups are not included into the main polymeric chain. 

The Ullman reaction has long been known as a method for the synthesis of aromatic ethers by the reaction of a phenol with an aromatic halide in the presence of a copper compound as a catalyst. It is a variation on the nucleophilic substitution reaction since a phenolic salt reacts with the halide. Nonactivated aromatic halides can be used in the synthesis of poly(arylene edier)s, dius providing a way of obtaining structures not available by the conventional nucleophilic route. The ease of halogen displacement was found to be the reverse of that observed for activated nucleophilic substitution reaction, that is, I > Br > Cl F. The polymerizations are conducted in benzophenone with a cuprous chloride-pyridine complex as a catalyst. Bromine compounds are the favored reactants.53,124 127 Poly(arylene ether)s have been prepared by Ullman coupling of bisphenols and... 

Since thiophene derivatives, heterocyclic aromatic compounds, are sensitive toward electrophilic substitution reactions, the bromination of these compounds generally gives a mixture of mono-, di-, and other poly-substituted bromination products (ref. 19). However, we have recently found that BTMA Br3 is a useful... 

FIGURE 2 Bromination, quaternization, and binding of heparin to the surface of poly[bis-(2 niethylphenoxy)phosphazene]. 

Morris PJ, JF Quensen III, JM Tiedje, SA Boyd (1993) An assessment of the reductive debromination of poly-brominated biphenyls in the Pine River reservoir. Environ Sci Technol 27 1580-1586. 

Halogenatlon. Poly(2,6-dimethyl- and 2,6-diphenyl-l,4-phenylene ether) can be aryl-brominated simply by exposure to a bromine solution no catalyst is required.6 In fact, the use of Lewis acid catalysts to promote the chlorination of poly(2,6-dimethy1-1,4-phenylene ether) leads to substantial degradation of the molecular weight of the chlorinated products.7 Membranes produced from ring brominated PPO (40% wt Br) exhibited enhanced permeability to CHi and CO2 and proved to be more selective in separating CH4/CO2 mixtures.8... 

Verdet and Stille1 employed brominated poly(phenylene oxide) intermediates in an effort to synthesize more stable catalyst supports containing (cyclopentadienyl)metal complexes. Treatment of poly(oxy-2,6-dimethyl-l,4-phenylene) with N-bromosuccinimide under photolytic conditions produced only the bromomethyl derivative if the D.F. did not exceed 0.35. Subsequent treatment of the bromomethylated polymer with sodium cyclopentadienide afforded the cyclopentadienyl functionalized polymer, 5, but the reaction was accompanied by crosslinking and it was not possible to remove the bromomethyl substituents quantitatively. 

The chemical modification of poly (2,6-dimethyl-l,4-phenylene oxide) (PPO) by several polymer analogous reactions is presented. The chemical modification was accomplished by the electrophilic substitution reactions such as bromination, sulfonylation and acylation. The permeability to gases of the PPO and of the resulting modified polymers is discussed. Very good permeation properties to gases, better than for PPO were obtained for the modified structures. The thermal behavior of the substituted polymers resembled more or less the properties of the parent polymer while their solution behavior exhibited considerable differences. 

The synthesis of luminescent organoboron quinolate polymers (21) (Fig. 15) via a three-step procedure starting from a silylated polystyrene has been communicated. The synthesis was initiated by the highly selective borylation of poly (4-trimethylsilylstyrene) (PS-Si), followed by the replacement of the bromine substituents in poly(4-dibromoborylstyrene) (PS-BBr) with substituted thienyl groups (R = H, 3-hexyl, 5-hexyl). In the final step, the 8-hydroxyquinolato moiety was introduced. The hexyl-substituted polymers efficiently emitted light at 513-514nm upon excitation at 395 nm.40... 

The residual double bonds of poly(methyl acrylate) have been determined by bromination [9,27]. Bromination is accomplished through the addition of potassium bromide to potassium bromate in acidic medium [9]. Styrene-butadiene copolymers contain residual double bonds. The butadiene content of the copolymer has been determined by an iodine monochloride titration procedure [9],... 

McCormack KM, Hook JB. 1982. Effects of lactation and nursing on tissue concentrations of poly brominated biphenyls and on microsomal enzyme activity in mammary gland and liver in maternal rats. EnvironRes 27 110-117. 

A soln. of twenty-two grains of iodine and thirty-three grains of iodide of potassium, in one ounce of distilled water forms the liquor iodi of the British Pharmacopoeia. The effects produced by the ammonium salts are attributed to their hydrolysis into ammonium hydroxide, and the consequent formation of ammonium iodide or polyiodide. The effects produced by soln. of the halide salts are doubtless due to the formation of poly iodides as in the analogous case with bromine and potassium bromide. A. A. Jakowkin allowed carbon disulphide to remain in contact with aq. soln. of iodine and potassium iodide until equilibrium was attained and... 

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