Poly brominated compounds

Effective use can sometimes be made of removable blocking groups on the ring. Suppose you are set the task of making pure < -bromophenol. Simple bromination of phenol will fail because of the dominant formation of the para isomer or of poly-brominated compounds (Fig. 14.90). A solution to this problem is first to sulfonate... 

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... 

Table 9 shows that there are reasonably good data available for the poly-brominated diphenyl ethers (PBDEs), but there is much less information for the other BFRs. While the polybrominated biphenyls (PBBs) are no longer in production or use, it is clear that these compounds are persistent in the environment and in people thus, it would be prudent to continue to monitor the concentrations of these compounds in (at least) the sediment and fishes of the lakes. The other BFRs (HBCD, TBE, and PEB) are not currently abundant in the lakes, but the likelihood of their increased use in the future suggests that they too should be monitored in the sediment and fishes of the lakes. Of course, the... 

In response to the continuing discovery of the persistence, bioaccumulative properties, and toxicity of POPs, regional, national and international policies ban the intentional production of compounds, such as polychlorinated biphenyls (PCBs), several organochlo-rine pesticides, such as mirex and dieldrin, and the brominated flame retardants poly-brominated diphenyl ethers (penta-BDE and octa-BDE, and most recently, deca-BDE). Policies and programs have also targeted the unintentional production and release of POPs such as polychlorinated dibenzodioxins and furans (PCDD/Fs). Evidence of the success of these policies has been seen in immediate reductions of air concentrations, followed by declining concentrations in water bodies, soils, biota and our food supplies... 

Stross JK, Smokier IA, Isbister J, et al The human health effects of exposure to poly-brominated biphenyls. Toxicol Appl Pharmacol 58 145-150, 1981 Tilson HA, Harry GJ Developmental neurotoxicology of polychlorinated biphenyls and related compounds, in The Vulnerable Brain and Environmental Risks, Vol 3 Toxins in Air and Water. Edited by Isaacson RL, Jensen KF. New York, Plenum, 1994, pp 267-279... 

Direct photoreaction (eq 4) is important only for halocarbons (e.g., aromatic compounds) that significantly absorb radiation at wavelengths >295 nm, the cutoff for solar spectral irradiance at the earths surface. Because saturated chlorinated and fluorinated organic compounds, including methylchloroform and chlorofluorocarbons, absorb solar radiation very weakly, their direct photoreaction is very slow in the sea and in fresh waters. As discussed in a later section, photoreactions of these compounds may be accelerated by sorption and indirect photoreactions in natural waters. Saturated and olefinic poly-brominated and iodinated organic compounds have long absorption tails that extend beyond 295 nm. Direct photoreaction of such compounds in aquatic environments may be significant. 

ANTIMONY SESQUIOXIDE (1309-64-4) Ignites and burns in heated air above 420°F/215°C. Violent reaction with bromine trifluoride. Reacts with chlorinated rubber, alco-hols/glycols, organic and a-hydroxy acids (fruit acids), o-dihydric phenols, polyethylene glycol, and other poly hydroxy compounds. 

Polymeric aromatic bromine compounds, such as poly(tribromostyrene), poly(pentabromobenzyl acrylate) or poly(dibromophenylene oxide) are suitable for application in polyamides, ABS, and polyesters. 

It is possible to form substituted poly(p-xylylene)s by starting with substituted structures. Among the compounds reported were chlorinated and brominated compounds as well as some containing alkyl, cyano, acetyl, and carboxymethyl derivatives. When the di-p-xylylenes are unsymmetrically substituted, two homogeneous polymers form during pyrolysis, because the two condense with spontaneous polymerization at two different temperatures. ... 

Many workshops and conferences on the bromine compounds have been held under auspices of govemment/nongovemmental organizations and industry (examples References 158-160). Concern has lately focused on the lower brominated diphenyl ethers (such as penta-) which are detected widely in the environment. In a review, Dutch researchers conclude that the toxicity mechanism of poly-brominated diphenyl ethers is the same as that of the dioxins, and, although the present concentrations are not a large risk, these ethers are accumulative. Decabromodiphenyl oxide is less toxic than the less-brominated congeners, and its absorption from the gastrointestinal tract is low. 

Brominated Styrene. Dibromostyrene [31780-26 ] is used commercially as a flame retardant in ABS (57). Tribromostyrene [61368-34-1] (TBS) has been proposed as a reactive flame retardant for incorporation either during polymerization or during compounding. In the latter case, the TBS could graft onto the host polymer or homopolymerize to form poly(tribromostyrene) in situ (58). 

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... 

Our objective In this paper is to illustrate the methods for functionalizing poly(arylene ether sulfone). Particular attention will be paid to bromination, nitration, aminatlon, chloromethyl-ation, and aminomethylatlon of 1 and its corresponding model compound. 

Selection of appropriate conditions to modify polymers is facilitated by preliminary studies with well designed model compounds. The work with model systems is critical when studying condensation polymers because the main chain linkages have proved to be remarkably labile under certain conditions. Condensation of 4-chlorophenyl phenyl sulfone with the disodium salt of blsphenol-A yields 2,2-bis[4 -(4"-phenylsulfonylphenoxyl)phenyl] propane, T, an excellent model for the poly(arylene ether sulfone) substrate. Conditions for quantitative bromination, nitration, chloro-methylation, and aminomethylation of the model compound were established. Comparable conditions were employed to modify the corresponding polymers. 

---