Norbomene styrene

The catalytic polymerization process is carried out in hydrocarbon diluents (diesel oil, hexane, isobutane) or the bulk monomers (ethylene, propylene, norbomene, styrene). The transition metal catalysts are usually insoluble and thus act heterogeneously, except for some homogeneously active vanadium compounds [2] and the metallocenes [20] (cf Section 2.3.1.1). Over a wide tempera-... 

Similar reactions were reported for isoprene and piperylene [49]. Terpolymers of 1,3-butadiene, sulfiir dioxide, and norbomene-styrene or cyclopentene were also reported [50]. An example of terpolymerization is illustrated in preparation 4-2. 

Rh2(OAc)4 is the most effective and versatile of the three catalysts used. Terminal and non-terminal olefins, strained olefins (norbomene, norbomadiene) and conjugated olefins (styrene) all react in good yield. 

Cu(OTf)2 generally gives yields intermediate between those of the other two catalysts, but with a closer resemblance to rhodium. In competition experiments, the better coordinating norbomene is preferred over styrene, just as in the case with Pd(OAc)2. Cu(acac)2, however, parallels Rh2(OAc)4 in its preference for styrene. These findings illustrate the variability of copper-promoted cyclopropanations, and it was suggested that in the Cu(OTf)2-catalyzed reactions of diazoesters, basic by-products, which are formed as the reaction proceeds, may gradually suppress... 

Alternating copolymers of ethylene with olefins containing double bonds in the cis configuration, like ds-2-butene, cyclopentene, cycloheptene,115 and norbomene,116 have been described. Recently also copolymers of carbon monoxide with styrene and styrene derivatives, having syndiotactic117 and isotactic118 configurations, have been synthesized and characterized. 

Insertion of aUcynes into aromatic C-H bonds has been achieved by iridium complexes. Shibata and coworkers found that the cationic complex [Ir(COD)2]BF4 catalyzes the hydroarylation of internal alkynes with aryl ketones in the presence of BINAP (24) [111]. The reaction selectively produces ort/to-substituted alkenated-aryl products. Styrene and norbomene were also found to undergo hydroarylation under similar condition. [Cp IrCl2]2 catalyzes aromatization of benzoic acid with two equivalents of internal alkyne to form naphthalene derivatives via decarboxylation in the presence of Ag2C03 as an oxidant (25) [112]. 

Ru(ti -C6H,)(CH3CN),](BF4)2 1-octene, 1-decene, styrene, 1-dodecene, cyclohexene, norbomene.dimethy 1 mateate, cyclohex-1 -ene-2-one, benzylideneacetone H20/benzene 90-110 C, 40 bar Hi Slow hydrogenation of ketones and aldehydes, too. [71]... 

The most common alkenes employed in the Pd-catalysed synthesis of alternating polyketones are ethene, styrene, propene and cyclic alkenes such as norbomene and norbornadiene. Even though the mechanism does not vary substantially with the alkene, the reactions of the various co-monomers are here reported and commented on separately, starting with the ethene/CO copolymerisation, which is still the most studied process. As a general scheme, the proposed catalytic cycles are presented first, then the spectroscopic experiments that have allowed one to elucidate each single mechanistic step. 

The absence of a second cyclopentadienyl ring coupled with the short bridge gives a very open environment at the metal site. This allows easier access for bulky monomers, including 1-alkenes and norbomene, compared to polymerization with metallocenes. CpA initiators yield ethylene copolymers not easily available with metallocenes. Copolymers containing significant amounts of comonomers such as styrene, norbomene, and a-olefins from 1-hexene to 1-octadecene are easily obtained with CpA, but not with metallocene or traditional Ziegler-Natta initiators. 

Some typical epoxidations are listed in Table 3.1. The first Ru-catalysed epoxida-tion was reported in 1983 by James et al., in which RuBrlPPh XOEPl/PhlO/CHjClj was used to epoxidise styrene, norbomene and c/x-stilbene in low yields trans-stilbene was not oxidised [588]. It was later noted that tranx-RulOl lTMPl/Oj/C H aerobically oxidised cyclic alkenes, and a catalytic cycle involving Ru 0(TMP) was proposed, in which there is disproportionation of Ru(0)(TMP) to Ru(TMP) and fran -Ru(0)2(TMP), the latter epoxidising the alkene and the former being oxidised back to the latter by (Fig. 1.26) [46, 583]. Stilbene, tranx-styrene and norbomene were efficiently epoxidised by trani-RulOl lTMPl/lCl pyNOl/CgH [589], as was epoxidation of exo-norbomenes catalysed by trani-RulOl lTMPl/Oj/ CgHg [590]. 

As stoich. [Ru(0)(bpy)(tmtacn)]VCH3CN it functioned as a competent (sic) epoxidant for alkenes, though the products were often contaminated with by-products (e.g. fran -stilbene gave fran -stilbene oxide and benzaldehyde cw-stilbene gave cis- and trans- epoxides). Kinetics of the epoxidation of norbomene and styrene were reported, with activation parameters measured and discussed [682]. Kinetics of its non-stereospecific, stoicheiometric epoxidation of aromatic alkenes in CH3CN were studied, and the rates compared with those of oxidations effected by other Ru(IV) 0x0 complexes with N-donors, e. g. [Ru(0)(tmeda)(tpy)] ", trans-[Ru(0)(Cl3bpy)(tpy)] " and [Ru(0)Cl(bpy)(ppz )] + [676]. 

RuCl(en)(DPA), RuCl(bpy)(DPA) and RuCl(phen)(DPA) (DPA=2,6-dipicolinic acid) are made by reaction of RUCI3, the diamine and DPA in ethanol under reflux. The IR spectra and magnetic moments (p. 1.84, 1.79 and 1.78 B.M. respectively) were measured. As RuCl(bpy)(DPA) and RuCl(phen)(DPA)/PhlO or TBHP/water-dioxane they epoxidised styrene and norbomene and oxidised cyclohexane to cyclohexanol and cyclohexanone. A Ru (0)Cl(diamine)(DPA) species may be involved [792]. 

RuBr(PPh3)(OEP) is made from Ru(PPh3)3(OEP) and Br. As RuBr(PPh3)(OEP)/ PhlO/CH Clj it epoxidised styrene, norbomene and cw-stilbene to their epoxides, but frawj-stilbene was not oxidised [588]. The reagent RuBr(PPh3)(OEP)/PhlO/CH3Cl2 oxidised cyclohexane and cyclohexene to a mixture of products [812]. 

The first Ru-catalysed epoxidation was reported in 1983 by James et al. using RuBr(PPh3)(OEP)/PhlO/CH2Cl2 with styrene, norbomene and aT-stilbene in low yields cf. mech. Ch. 1 [23]. Eater work showed that fran -Ru(0)2(TMP)/02/CgHg catalysed aerobic alkene epoxidation of cyclo-octene, cis- and trans- -methylstyrenes and norbomene (Fig. 1.26) [24],... 

Much exploratory work has been done on model substrates. Epoxidations of cyclo-octene and styrene give relatively clean products, and several studies have also been carried out on styrene, norbomene and 1-octene. 

For cyclo-octene and -hexene, styrene, stilbenes, norbomene and 1-octene, cf. 3.1.1.1 ... 

Nitrosyl formate may be generated in situ by treating isopentyl nitrite with anhydrous formic acid. This reagent evidently adds to olefins such as cyclohexene, styrene, norbomene, trans-3-hexene, and 2,3-dimethylbutene to give nitrosoformates. While the first three olefins were converted into dimeric products, 2,3-dimethylbutene produced a 50-50 mixture of the monomer and the dimer (as a blue oil). The product of the reaction with trans-3-hexene contained some of the corresponding oximino formate. 

Another important use of BC13 is as a Friedel-Crafts catalyst in various polymerization, alkylation, and acylation reactions, and in other organic syntheses (see Friedel-Crafts reaction). Examples include conversion of cydophosphazenes to polymers (81,82) polymerization of olefins such as ethylene (75,83—88) graft polymerization of vinyl chloride and isobutylene (89) stereospecific polymerization of propylene (90) copolymerization of isobutylene and styrene (91,92), and other unsaturated aromatics with maleic anhydride (93) polymerization of norbomene (94), butadiene (95) preparation of electrically conducting epoxy resins (96), and polymers containing B and N (97) and selective demethylation of methoxy groups ortho to OH groups (98). 

Simple alkenes, norbomene and styrene do not undergo cyclopropanation or insertion reactions with cyclopropyl(methoxy)carbene chromium pentacarbonyl complex. However, the conjugated 1-vinylcyclopentene is cyclopropanated under the reaction conditions at the terminal double bond, affording an isomeric mixture (trans cis = 40 60), in 66% yield (equation 72). 

The hydroformylation of styrene in triethyl orthoformate is slower than that observed in benzene, but a 98% ee is obtained, since racemization of the product acetal does not occur. Hydrolysis of the acetal to the aldehyde can be accomplished without racemization. A number of other substrates are hydroformylated in the presence of triethyl orthoformate. The reactions are slower, but with all substrates tried except norbomene, enantiomerically pure products can be obtained. 

Additions occur more easily if a carbanion with resonance or inductive stabilization is formed in the addition. Thus, fulvenes are very reactive, vinylsilanes and highly fluorinated alkenes somewhat less so. Styrene, 1,3-dienes, and enynes are more reactive than isolated alkenes, and Grignard reagents may be used to initiate anionic polymerization of styrenes, dienes, and acryhc monomers. Strained alkenes such as norbomenes and cyclopropenes are also more reactive. Examples of additions facilitated by resonance or substitution are shown in Scheme 8. 

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