P-Chlorostyrene

In the last example, where p-chlorostyrene-12% DVB resin was sequentially polysulfonated and chlorinated and base treated to give resin E, characterized by high exchange capacity, stability and low bleed. We hypothesize that blocking the para position to sulfonation in the polymer leads to enhanced stability. 

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. 

The Arrhenius curvature could be attributed to the occurrence of two competing reactions with different activation energies. However, photolysis of 9a at —80°C afforded only p-chlorostyrenes 11a and 12a no carbene-solvent insertion product was detected, and reaction of the carbene with diazirine to give azine was considered unimportant at the diazirine concentrations employed. 

Accordingly, a re-examination of the benzylchlorocarbene system was performed, with close attention paid to the products formed at low temperature.71 Carbene 10a was photolytically generated from diazirine 9a in isooctane, methylcyclohexane, and tetrachloroethane at temperatures ranging from 30 to —75°C. At —70°C in isooctane, the products included 47% of P-chlorostyrenes 11a and 12a, 2.4% of a-chlorostyrene (49), 2% of dichloride 50, 5.5% of a C-H insertion product of 10a and isooctane, 4% of the dimers of 10a, and 30% of azine 48.71 The sum of the intermolecular products at —70°C was thus 41.5%, of which azine was the principal component. 

Scanty though our information is, it indicates that most aromatic monomers show very similar kinetic behaviour under similar conditions. Moreover, it has recently been shown that the very simple kinetics of the polymerization of styrene by perchloric acid [27, 82] also apply to polymerization of p-chlorostyrene [83] by that catalyst. From concurrent studies of co-polymerization Brown and Pepper deduced that styrene gives a more reactive active species than p-chlorostyrene, and that styrene is the more reactive monomer. The former conclusion is not easily compatible with an ion being the chain-carrier. 

In a comparative study [130] with p-chlorostyrene as model substrate, the influence of the oxygen source in CPO-catalyzed epoxidation was investigated. The time profile for the substrate conversion and product formation are shown in Fig. 7 for fBuOOH (a) and H2O2 (b). Both oxygen donors exhibit the same selectivities (ee 66-67%) but with fBuOOH the epoxide was obtained in 35% yield and H2O2 afforded only 11 % of the product. 

Uses Intermediate in production of styrene, acetophenone, ethylcyclohexane, benzoic acid, 1-bromo-l-phenylethane, 1-chloro-l-phenylethane, 2-chloro-l-phenylethane, p-chloroethylbenz-ene, p-chlorostyrene, and many other compounds solvent in organic synthesis. 

Figure 37. The effect of change in molecular weight at constant dispersity on the e-beam sensitivity of poly(p-chlorostyrene). The very high contrast was achieved by fractionating to obtain nearly monodispersed samples.

Under identical conditions the aromatic olefins styrene and p-methylstyrene give the vic-dimethoxy adducts as the sole products. Methoxytellurenylated adducts are formed, however, as minor by-products from different substituted olefins (p-chlorostyrene) or exclusively (from styrene) when the amount of H2SO4 is reduced. 

Among the most extensive studies of monomer reactivity have been those involving the copolymerization of various meta- and para-substituted styrenes with other styrene monomers (styrene, a-methylstyrene, and p-chlorostyrene) as the reference monomer [Kennedy and Marechal, 1983], The relative reactivities of the various substituted styrenes have been correlated by the Hammett sigma-rho relationship ... 

TABLE 6-9 Steric Effects in Cationic Copolymerization of a- and (i-Methylstyrenes (Mx) with p-Chlorostyrene (M2)a b... 

It has previously been shown that large changes can occur in the rate of a cationic polymerization by using a different solvent and/or different counterion (Sec. 5-2f). The monomer reactivity ratios are also affected by changes in the solvent or counterion. The effects are often complex and difficult to predict since changes in solvent or counterion often result in alterations in the relative amounts of the different types of propagating centers (free ion, ion pair, covalent), each of which may be differently affected by solvent. As many systems do not show an effect as do show an effect of solvent or counterion on r values [Kennedy and Marechal, 1983]. The dramatic effect that solvents can have on monomer reactivity ratios is illustrated by the data in Table 6-10 for isobutylene-p-chlorostyrene. The aluminum bromide-initiated copolymerization shows r — 1.01, r2 = 1.02 in n-hexane but... 

Donor-acceptor interaction between monomer and polymer template offers an elegant methods of replication degree of polymerization. Similar system was described for copolymerization of vinylpyridine with p-chlorostyrene in the presence of poly(maleic anhydride) used as template. " ... 

It was found that a mixture of 4-vinylpyridine with p-chlorostyrene copolymerizes without any initiator in the presence of poly(maleic anhydride) at 50°C in DMF. The fact that poly(maleic anhydride) cannot initiate the polymerization of styrene or phenyl vinyl ether shows that poly(maleic anhydride) does not act as a normal anionic or cationic initiator. The compositions of copolymers obtained with various initial compositions of... 

Preparation of Octa-Arm Poly(p-chlorostyrene-b-isobutylene) Stars... 

Because of increased steric hindrance, the polymers of p-chlorostyrene have higher heat deflection temperatures than PS. Polydichlorostyrene (Styr-amic) has a heat deflection temperature of 120 C and a specific gravity of 1.4,... 

This work on organometallic resists was extended by MacDonald et al. (126) to include poly(trimethylstannylstyrene) and poly(trimethylsilylstyrene) together with copolymers of these materials with p-chlorostyrene. The sensitivity of the stannyl derivative to electrons is reported to be 0.5 / 2, and the copolymer with p-chlorostyrene could be patterned in the deep UV at a dose of 10 mJ/cm2 at 254 nm. The materials show excellent oxygen RIE resistance due to the formation of involatile oxides of the metals on the surface of the pattern. 

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