Styrene and derivs

For the addition of ethylene, EtOAc as solvent was particularly advantageous and gave 418 in 60% yield (Scheme 6.86). The monosubstituted ethylenes 1-hexene, vinylcyclohexane, allyltrimethylsilane, allyl alcohol, ethyl vinyl ether, vinyl acetate and N-vinyl-2-pyrrolidone furnished [2 + 2]-cycloadducts of the type 419 in yields of 54—100%. Mixtures of [2 + 2]-cycloadducts of the types 419 and 420 were formed with vinylcyclopropane, styrene and derivatives substituted at the phenyl group, acrylonitrile, methyl acrylate and phenyl vinyl thioether (yields of 56-76%), in which the diastereomers 419 predominated up to a ratio of 2.5 1 except in the case of the styrenes, where this ratio was 1 1. The Hammett p value for the addition of the styrenes to 417 turned out to be -0.54, suggesting that there is little charge separation in the transition state [155]. In the case of 6, the p value was determined as +0.79 (see Section 6.3.1) and indicates a slight polarization in the opposite direction. This astounding variety of substrates for 417 is contrasted by only a few monosubstituted ethylenes whose addition products with 417 could not be observed or were formed in only small amounts phenyl vinyl ether, vinyl bromide, (perfluorobutyl)-ethylene, phenyl vinyl sulfoxide and sulfone, methyl vinyl ketone and the vinylpyri-dines. 

Styrene and Derivatives, See under Dinitro-polystyrene in Vol 8, N143-L to N144-R. The following is an addnl compd of interest 2,4,6-Trinitrostyrene. 

Styrene (and derivatives) also possesses the rare monomer quality that the neat material, without initiator, may be spontaneously polymerized by simply heating to 80-100°C for 24-48 hr. It is thought that this occurs via the initial Diels-Alder dimerization of styrene to the two diasteomers A and B [14]. The two diastereomers appear to have an extremely labile hydrogen, which is both doubly allylic and tertiary. However, only dimer A has the correct stereochemistry (an axial phenyl), which enables the excess styrene to abstract a hydrogen atom from it, producing two radical species (Eq. 23.5). 

Chem. Descrip. Dioctyl maleate CAS 2915-53-9 EINECS/ELINCS 220-835-6 Uses Comonomer used in polymerization with vinyl acetate, vinyl chloride, styrene and derivs. of acrylic and methacrylic acids used in latex paints, textiles as specialty plasticizer Properties APHA50 max. liq. m.w. 340 sp.gr. 0.939-0.944 vise. 9.1-9.5 cs (100 F) pour pt. -75 F acid no. 0.10 max. flash pt. (COC) 370 F ref. index 1.452-1.454 94% act. 

Functionalized initiators have been used extensively for styrene and derivatives to obtain end-functionalized polymers by living cationic polymerization. 

Oxidative Heck reactions via Pd(II) C—H functionalization of terminal alkenes with pinacol boranes have been described for the preparation of styrenes and derivatives through electrophilic Pd(II) catalysis (Scheme 3.20). ° Treatment of a functionalized allylic precursor with the Pd(II) catalysts listed facilitated an allylic C—H activation. Subsequent transmetallation of the aryl boronic acid and reductive elimination afforded the desired olefin with excellent stereoselectivity. The scope of the transformation allows for a variety of activating and deactivating substituents on the aryl boronic acid as well as numerous functional groups on the starting alkene. A tandem allylic C—H oxidation/vinylic arylation protocol has also been reported. " ... 

Demonceau and Vinas et al. [68] demonstrated cyclopropanation of several olefins with ruthenium and rhodinm complexes 62-66 of m7/o-carboranes (Scheme 22.19, Figure 22.23) [65,68]. They observed a conversion between 90% and 98% for both of the ruthenium complexes, where activated olefins, such as styrene and derivatives thereof, were used as substrates (Table 22.28). The yields were significantly lower with cyclic olefins or terminal linear mono-olefins (51-65%). Similar results... 

Radical initiators, including AIBN, are widely employed as initiators in this kind of polymerization while, among the monomers, methacrylates, methacrylamides, acrylonitrile, styrene and derivatives are commonly used. 

Wessling [9] studied the reaction kinetics of semibatch emulsion polymerization of relatively hydrophobic monomers such as styrene and derived the following expression for the rate of polymerization at pseudo-steady state (Rp) ... 

On the other hand, the biocatalytic epoxidation of styrene and derivatives can be achieved with excellent stereoselectivity using SMOs of various origins (Scheme 13.9). Although isolated SMO has been successfully applied in combination with enzymatic NADH regeneration [92,97] or reductive electrochemical cofactor regeneration [98-101], the process based on E. coli whole cells expressing those SMOs has been proven superior in terms of productivity due to the limited stability of cell-free enzymes, and consequently it has been applied in the majority of reported studies. 

In contrast to SMOs, which exclusively catalyze the formation of (S)-epoxides, CPOs are able to yield chiral (P)-epoxides from styrene derivatives, which could serve as a stereocomplementary method (Scheme 13.11). However, the substrate spectrum appeared to be very limited [85,109]. Two ds-disubstituted aryl-substituted alkenes, czs-a-methylstyrene and 1,2-dihydronaphthalene, were effectively epoxi-dized in the presence of H Oj, and the later underwent spontaneous hydrolytic ring opening to afford the corresponding trans-diol. The enantiomeric excesses of the products were as high as 96% and 97% ee, respectively [83]. Terminal alkenes such as styrene and derivatives with a halide substituent on the benzene ring [109] or an alpha-alkyl substituent [85] could be accepted by CPO, and underwent epoxidation using f-BuOOH or HjOj as the oxidant, but the (P)-epoxides were achieved with only low to medium enantiopurity [83,85,109]. 

Poly(styrene) and Derivatives VI1-1 9 6.6. Poly(styrene) and Derivatives VI1-54... 

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