Styrene fragment

The incrrase of surface area and pore volume enhanced the production of ethylbenzene by promoting further hydrogenation of the degraded styrene fragments. High degradation temperature favored the selectivity to styrene monomer. 

C13-0006. In a 3 1 copolymer of butadiene and styrene, the placement of butadiene and styrene fragments along the chain is random. Draw a line stmeture for a portion of the copolymer that has this sequence -butadiene-styrene-styrene-butadiene-. 

An appropriate balance of hydrophilicity and hydrophobicity in the molecular structure of polyampholytes is believed to be a key component in demonstrating the solubilization of organic probes and gelation properties [58]. The existence of hydrophobic clusters consisting of hydrophobic vinylbutyl ether (or styrene) fragments has been shown for alternating copolymers of vinylbutyl ether (or styrene) and AT,N-dimethylaminopropylmonoamide of maleic acid... 

If two different methylene groups compete for creation of the pyrrole ring (as it takes place in, e.g benzyl ethyl ketoxime), the competition is won by group that is in Zt-position relative to hydroxyl, that is, by methylene function of the benzyl radical. In this case, conjugation with the benzene ring (formation of the styrene fragment) contributes additionally to stabilization of the ethylene counterpart of hydroxyl-amine O-vinyl ether formed. 

The cyclohcxadicnc 84 is a good H donor but the cyclohcxadicnyl radical 85 is slow to react and fragments to provide the silyl radical 86 which initiates polymerization. The reported transfer constant for 84 in styrene polymerization at 80 °C is very low (0.00045).ni>... 

Both trans-l amino-2,3-diphenylaziridine and l-amino-2-phenylazi-ridine give a,/S-epoxyhydrazones that fragment in the desired manner between 100° and 200°, the choice of reagent being dictated by the ease of separation of the alkynone from the by-products, (F/)-stilbene and styrene, respectively. The diphenylaziridine is especially useful when the alkynone is relatively volatile and easily separable by distillation from (E)-stilbene, as is the case in the present example. The phenylaziridine... 

Several other methods have been demonstrated for determining the efficiency/. The most direct of these depends on a quantitative assay of the polymer for initiator fragments, which may then be compared with the amount of initiator decomposed. Evans, in the work to which previous reference was made on the polymerization of styrene by hydrogen peroxide and ferrous ions in aqueous solution, showed not only that each polymer molecule thus formed contained two hydroxyl groups, but also that the number of moles of hydroxyl groups found in the polymer was very nearly equivalent to the moles of peroxide decomposed. Since... 

Bartlett and co-workers concluded that addition to the nitro group also occurs. Price and Read found that several m-dinitrobenzene molecules were combined with the polymer for each fragment from the p-bromobenzoyl peroxide used as initiator in the retarded polymerization of styrene. They inferred that the radical corresponding to IV transfers its hydrogen atom to a molecule of styrene as follows ... 

Styrene hydrozirconation led to a ratio for terminal and benzylic zirconocene products of around 85 15 [97]. Experimental evidence on alkyl-substituted styrene suggested that both electronic [98,99] and steric effects [41,86] are important for the formation of the benzyhc and terminal zirconium isomers. Migration of the metal fragment during the reaction of the zirconocene moiety might occur, perturbing the terminal/benzyl regioisomer ratio of the isolated products (Scheme 8-11) [67, 83, 98-102]. 

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