3-methylstyrene

The polymerisation of this monomer by stable carbenium salts was first reported by Sauvet et who only remarked that at —70°C in methylene chloride, about 30% yield was obtained in two hours with a 10 M concentration of trityl hexachloroanti-monate. In the same year, Higashimura et al. measured the rate of interaction between trityl pentachlorostannate and a-methylstyrene at 30-60°C in ethylene chloride and mixtures of this solvent with benzene. They monitored the disqipearance of the characteristic visible bands of the trityl ion as the reaction proceeded. Good first order plots were obtained and the external order in monomer was found to be unity so that kinetically the reaction was bimolecular with a kj of 1.3 min at 30°C in pure eth- 

Kunitake s group has reported on two occasions observations about the polymerisation of this monomer by a whole family of trityl salts at —78°C in solvents of various polarities. Polymerisations were reported to be slow, particularly in media of low dielectric constant. These studies were not concerned with the medianism of initiation or with the kinetics of polymerisation but rather with the influence of the counterion on the steric structure of the polymers obtained in conditiorB where ion pairs predominate over free ions. No further studies have been published on this monomer. 

In conclusion, althoi it is known that trityl salts can initiate the polymerisation of amiethylstyrene and that the polymerisation is rather slow, no systematic study has yet been carried out on these sterns and the chemistry of initiation is stfll unknown. 

Reports on the possibility of inducing the polymerisation of styrene by trityl salts are among the oldest in this field . However, surprisingly enou these processes have not yet been fully explored. Styrene is rather reluctant to react with the trityl ion and does not react at all with the tropylium ion. The latter observation has been reported by Ledwith and Sherrington vidro describe an experiment in diichp-methoxystyre- 

Sambhi and Treloar published in 1965 a brief study of the polymerisation of st3T ene by a mixture of trityl chloride and mercuric chloride in ethylene chloride at 30°C. The following medianism was proposed on the basis of their experimental results  

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Synonym 2-methylstyrene, 2-vinyl toluene, omclhyl vinyl benzene... 

The use of a chemical mediator can alter the chemoselectivity of an electrochemical reaction. In the reaction illustrated in Scheme 2, -methylstyrene was oxidized using both direct electrolysis and mediated conditions [10]. The current density, amount of charge passed, temperature, and other variables were all kept constant. The only difference was the addition of 6.4 mole percent of tris(4-bomophenyl)amine to the mediated reaction. The direct electrolysis tended to afford the product of a four-electron oxidation (7). When 3.5 F mole of electricity was passed, a 55% yield of (7) was obtained along with a 45% yield of (6). With additional current (6.4 F mole ), a 75% yield of (7) was obtained. The mediated process led to a preponderance of the product from the two-electron oxidation. When 3.5 F mole of electricity was passed in the experiment using the triarylamine mediator, a 93% yield of (6) was obtained along with only 6% of the four-electron oxidation product. 

As complex/aq. H O /CH Cl they epoxidised unfunctionalised alkenes RCH=CHj to a mixture of the epoxide and the aldehyde RCHO with e.e. values from 4% to 41%. Thus (Z)-2-methylstyrene gave the cw-epoxide with only traces of the trans-isomer [928, 929]. The reagent [RuCl(PNNP)]Vaq. H O /CH Cl epoxidised cis-stilbene, Z-2-methylstyrene and 1,2-dihydro-napthalene [844]. 

The photo-cross-linkability of a polymer depends not only on its chemical structure, but also on its molecular weight and the ordering of the polymer segments. Vinyl polymers, such as PE, PP, polystyrene, polyacrylates, and PVC, predominantly cross-link, whereas vinylidene polymers (polyisobutylene, poly-2-methylstyrene, polymethacrylates, and poly vinylidene chloride) tend to degrade. Likewise, polymers formed from diene monomers and linear condensation products, such as polyesters and polyamides, cross-link easily, whereas cellulose and cellulose derivatives degrade easily. ... 

In the liquid phase there are many examples of ionic polymerizations of olefinic compounds induced by high energy radiation. In some, such as propylene,77 1-hexene,78 1-octene,18 and n-hexadecene-1,75 the initiating ionic species is believed to be the parent ion radical while in others such as isoprene,79 isobutylene,80 butadiene,81 and 2-methylstyrene,82 it is thought to be the carbonium ion. 

So far, only examples of A-D-D triplexes have been discussed. One example of an emissive A-D-D triplex was recently reported by Pac and co-workers [115]. Excited singlet 1,4-dicyanonaphthalene forms exdplexes with benzene derivatives whose emission is quenched by a variety of aromatic olefins. This quenching is accompanied by the appearance of new emissions at longer wavelengths which has been assigned to a A-D-IT triplex with e.g., A = 1,4-dicyanonaphthalene, D = benzene, D = 2-methylstyrene. 

Mechanism of Shi epoxidation was probed for synthesis of (+)-(R,R) epoxide 20 in the reaction of frans-2-methylstyrene 18 with peroxymonosulphate (Oxone) in the presence of catalyst 19, chiral ketone derived from fructose (Scheme 5).74... 

Figure 9 Experimental and predicted (in brackets), 3C KIEs for Shi epoxidation of trans-2-methylstyrene 18.

Ene addition products have been isolated from reactions with various alkenes containing allylic hydrogen atoms compounds 49 and 50 are shown here as examples. Analogously, the reaction with a 1-alkyne furnishes the adduct 47 while styrene, in contrast, reacts to afford the [2 + 2] cycloaddition product 51. The latter mode of reaction, however, is no longer considered to be unusual since the tetraalkyldisilene 41 also forms [2 + 2] cycloadducts with various C=C double bond systems71-73. On the other hand, until very recently [2 + 2] cycloadditions of the tetraaryldisilene 9 were unknown. It has now been shown that 970, as well as 4171, can undergo cycloadditions with the C=C double bonds of styrene and 2-methylstyrene. [4 + 2] Cycloaddition reactions of disilenes with... 

Fig1. 12. NMR spectra of (a) 20% solution of poly-oc-methylstyrene in carbon tetrachloride and (6) 10% solution of poly-2-methylstyrene in carbon tetrachloride... 

Benzyl- or cinnamyl-triphenylarsonium bromides, upon reaction with aqueous sodium hydroxide at 100 °C, decompose into triphenylarsine oxide and toluene or 2-methylstyrene, respectively . Since tertiary arsine oxides spontaneously racemize in water , alkaline hydrolysis of arsonium salts of this type cannot be used for the preparation of optically active arsines. 

Also in 2000, attachment of the Jacobsen catalyst to polymeric supports such as poly(ethylene glycol) and different polystyrene-based resins through a glutarate spacer was described [28]. Soluble as well as insoluble polymer-bound complexes were employed as catalysts in the epoxidation of styrene, cfs-2-methylstyrene, and dihydronaphthalene with wx-CPBA/NMO. Results were similar to those achieved with the nonsupported catalyst. Catalyst recycling was shown to be possible either by filtration or by precipitation and one catalyst system could be used for three cycles without significant loss of activity and enantioselectivity. 

Mn(salen)-cross- linked triethynylbenzene cis-2- Methylstyrene wi-CPBA/ NMO 2 0... 

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