Poly supports bromination

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. 

Poly(4-vinylpyridine)-supported bromate in nonaqueous solution has been used in the bromination of aromatic compounds with potassium bromide <2005SC1947>. This bromination method is simple, efficient, mild, and selective for methoxyarenes, anilines, and phenols. 

Related anchored l,l,3,3-tetraphenyl-2-oxa-l,3-diphospholanium bis-triflate (39) has been prepared by reaction of brominated poly(styrene-co-divinylbenzene) resin 38 with the phosphorous anion generated from l,2-bis(diphenylphosphino)ethane and sodium naphthalenide followed by further oxidation and reaction with triflic anhydride (Scheme 7.13) [55]. This supported reagent has also been employed, to a lesser extent than 37, for the formation of esters and amides by reaction of carboxylic acids with primary alcohols and amines, respectively. 

Prins et al. (21) described the lower flammability of poly-bromostyrene relative to that of polystyrene. On the basis of thermal analysis experiments, they suggested that bromine inhibited most of the oxidative chain reactions, and thus the combustion was not supported (vapor-phase mechanism). Khanna and Pearce (16) and Brauman (22) demonstrated that polystyrene could be flame retarded by appropriately modifying its structure with substituents that promote the char yield of the system (condensed-phased mechanism). 

Polysiloxane-supported tethered metallocenes have been synthesized by reaction of brominated poly-(methylhydrogen)siloxane—poly(dimethylsiloxane) with NaCp and subsequent reaction with ZrCh (Scheme 12).166 Cohydrolysis of Cl2Si(Cp )(Flu) and Me2SiCl2... 

Raman studies, which will be dealt with later in more detail, show that the iodinated and brominated films should be formulated as [(CH) (l3) " at least a significant portion of the halogen being present as the I3 ion [58]. The halogen partly depopulates the n-bonding system and oxidizes the (CH) to a poly-carbonium ion chain. This conclusion is supported by carbon Is core shifts from ESCA studies [59]. 

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