P-Bromostyrene

The above methods occurred in 3 steps, therefore, these methods are not preferred. For instance, in the first step, o-, m-, and p-bromostyrene and its copolymer are synthesized. In the second step, Li-PS is synthesized from the reaction of copolymers with an organic compound containing LI. The abovementioned reactions are made with different compounds of Li-PS in the third step. These methods were also investigated by Ayres and Mann [34], who used the synthesis of PS containing chloro groups with chloromethylated PS as the first step. In the second step, formil resin was obtained by oxidation of chlorometylated PS. In the third step, carboxyl-ated PS was obtained by the oxidation of formol resin with acetic acid at 20°C for 48 h. There are some disad-... 

Fig. 7a, b. PMIM-image of (a) a poly-p-bromostyrene surface [118], (b) a PS/polybutadiene diblock copolymer, PS-b-PB, at approximately 100 fold magnification. The lateral resolution is of the order of 1 pm while the height resolution is of the order of 0.6 nm. The root-mean-square roughness averaged over the area shown is 0.8 nm in (a) close to the resolution limit of the technique. It is much larger (10 nm) in (b) due to the formation of steps after annealing. The scale in z-direction in (a) and (b) is different by a factor of 7... 

Fig. 10. X-ray reflectivity curves of polystyrene (PS)/poly-p-bromostyrene (PBrS) on a glass substrate before (solid line) and after annealing for 13 h at 130 °C (dashed tine) [191]. The width of the interface changes from 1.3 nm to 2.0 nm due to interfacial mixing of components. The X-ray wavelength is 0.154 nm and films have a thickness of 37.8 nm (PS) and 45.0 nm (PBrS), respectively...

Some of the vinyl monomers polymerized by transition metal benzyl compounds are listed in Table IX. In this table R represents the rate of polymerization in moles per liter per second M sec-1), [M]0 the initial monomer concentration in moles per liter (M) and [C]0 the initial concentration of catalyst in the same units. The ratio i2/[M]0[C]0 gives a measure of the reactivity of the system which is approximately independent of the concentration of catalyst and monomer. It will be observed that the substitution in the benzyl group is able to affect the polymerization rate significantly, but the groups that increase the polymerization rate toward ethylene have the opposite effect where styrene is concerned. It would also appear that titanium complexes are more active than zirconium. The results with styrene and p-bromostyrene suggests that substituents in the monomer, which increase the electronegative character of the double bond, reduces the polymerization rate. The order of reactivity of various olefinically unsaturated compounds is approximately as follows ... 

Figure 5 is an ORTEP computer plot of the first 50 backbone carbons in a typical chain. Only the fluorine atoms of the sidechains are shown. The various hard sphere exclusions conspire dramatically to keep the fluorines well separated and the chain highly extended even without introducing any external perturbations. The characteristic ratio from the computer calculations is about 11.6 from data for poly(p-chlorostyrene), CR = I l.l, poly(p-bromostyrene), CR = 12.3, and poly(styrene), CR = 10.3 (all in toluene at 30°C), we expect the experimental value for the fluoro-polymer to be in the range of 10 to 12. 

In figure 1 we present the experimental and calculated mK values of the copolymer poly(styrene-co-p-bromostyrene). From this study (3) we were able to show unequivocally that the tacticity of this polystyrene sample is pr — 0.55, where pr is the probability of racemic dyad replication. 

Figure 1. Molar kerr constant values (x 10 ucm7SC 2mot ) calculatedforpolyfstyrene-co-p-bromostyrene) copolymers as a function of composition Cand tact icily pr Black squares are experimental results. (Reproduced from Ref 3. Copyright 1981, American...

Phenyl-acetylene has been obtained in good yields by adding 1 mole of P bromostyrene to a well-cooled (-33°) suspension of 2 moles of sodium amide in liquid ammonia. After the vigorous reaction has subsided, the compound is separated by adding plenty of water. 

Bicyclo[2.2.1]hept-2-enes react with p-bromostyrene to form 1 2 adducts 2-(phenylethynyl)-3-(2-phenylethenyl)bicyclo[2.2.1]heptane and the ring-closed tricyclo compound are both isolated (Scheme 6.32) [45]. Comparison of these results should be with those of the reaction in the absence of the quaternary ammonium salt, where the major reaction pathway leads to 2 1 and 1 1 adducts [46]. 

The reaction has also been applied to the conversion of vinyl bromides into acrylic acids, e.g. 1-bromo- and 1-chlorocyclooctene are converted into cyclooctene-1-carboxylic acid (ca. 98%) [3], 2-chloro-3,3-dimethylbut-l-ene yields 4,4-dimethylpent-2-enoic acid (95%), and tams-cinnamic acid is obtained (85%) from fran.v-p-bromostyrene. cis-p-Bromostyrene produces a mixture of cis- and trans-cinnamic acids in 38 and 42% yields, respectively [3]. In these reactions, benzyltri-ethylammonium chloride cannot be used as the phase-transfer catalyst, as it leads to the production of phenylacetic acid [3]. 

Methylenation reaction (typical procedure) A mixture of iodomethyl triphenylphosphonium iodide (0.530 g, 1.0 mmol), dibutyl telluride (0.242 g, 1.0 mmol) and p-bromoben-zaldehyde (0.096 g, 0.5 mmol) in THF (5 mL) is heated under reflux for 30 h, then cooled and filtered. The residue is purified by TLC, giving p-bromostyrene (0.080 g (87%)). 

Cobalt(lll)(salen) catalyses the carboxylation of benzyl chlorides and allyl chlorides but not of halobenzenes [246], PdCl2(PPh3)2 catalyses the carboxylation of aryl halides, P-bromostyrene and allyl acetates [247]. 

The reaction of 1-phenylethyl-, 2-octyl-, and 2-butyl-magnesium chloride (36a, b, c) with vinyl bromide (37a), (E)-p-bromostyrene (37b), 2-bromopropene (37c), and bromobenzene (37d) was carried out in the presence of 0.5 mol- % of a nickel catalyst prepared in situ from nickel chloride and the chiral ligand (35). 

By the reaction of bromotoluene with ethylene under pressure, p-methylsty-rene and stilbene (45) are obtained[44,45]. A polymer 47 is obtained by the reaction of p-bromostyrene (46) with ethylene. The reaction has been applied to polymer synthesis[46]. One example is the reaction of 1,4-divinylbenzene (48) with 9,10-dibromoanthracene to give the oligo(arylenevinylene)s 49[47],... 

In reaction (10), poly-p-bromostyrene was prepared by the bromina-tion of polystyrene. However, this may also be synthesized by polymerizing p-bromostyrene in the presence of divinylbenzene using benzoyl peroxide as the polymerization initiator. The subsequent treatments are essentially similar to those in reaction (10), for example,... 

Experimental values are presented of the molar Kerr constants /x and dipole moments squared, lx, for the copolymers poly(styrene-co-p-bromostyrene), where x is the degree of polymerization. Some results are also presented for poly(styrene-co-p-chlorostyrene) and related polymers. The RIS model of Yoon etal. (Yoon, D. Y. Sundararajan, P. R. Flory, P. J. Macromolecules 1975, 8, 776) is used to calculate mK/x and /x values as a function of tacticity and composition. The statistical weight matrices are identical with those used by Saiz etal. (Saiz, E. Mark, J. E. Flory, P. J. Macromolecules 1977, 10, 967), with the following parameters h = 0.8 exp 397/RT), co = o = 1.3 exp - 1987/RT) and m,= 1.B exp -(2186/RT), where T = 298 K is the temperature. 

Though reduction of aromatic halides with NaBH4 does not proceed at all, photolytic treatment of the same aromatic halides and NaBH4 with a mercury lamp provides the reduction products via SET pathway. Eq. 9.3 shows the reduction of fra/is-P-bromostyrene (6) with LiAlD4 via SET pathway. The vinyl radical rapidly inverses on the sp2 carbon-centered atom, so a mixture of cis- and trans-styrenes (7a) and (7b) with dx/d0 = 63/37 is formed. <70-Styrene is again formed through the abstraction of a hydrogen atom from the solvent by the vinyl radical. Since the... 

Fig. 5. Miscibility of poly(2,6-dimethyl phenylene oxide) (PPO) and random copolymers of styrene and o-bromostyrene (7), p-fluorostyrene (2), p-bromostyrene (i), o-chlorostyrene (4), p-chlorostyrene (5), and o-fluorostyrene (<5) for 50/50 blends. Miscibility occurs to the left of the curves (after Ref. [29])...

PPO/poly(o-fiuorostyrene-ran-p-bromostyrene) miscibility between 11 and 73 mol% p-bromostyrene [46]... 

Recently, the stability of living poly-p-bromostyrene was investigated by Jagur 3S) who postulated a radical mechanism to account for the observed phenomena. Here again terminal double bonds are formed, KBr being eliminated ... 

Vinylation of various azoles (pyrrole, indole, carbazole, and their derivatives) with vinyl bromides catalyzed by palladium/phosphine complexes results in the A -vinylazoles in 30-99% yields (Equation 49) <20020L623>. This reaction with cis- and /ra r-P-bromostyrenes is stereospecific giving the respective products with full retention of configuration. 

PPA PpBrS PpCIS PPeMA PPFE poly(n-propyl acrylate) poly(p-bromostyrene) poly(p-chlorostyrene) poly(n-pentyl methacrylate) polylperfluoro ethers)... 

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