Propene-norbomene

Propene—norbomene (P—N) copolymers were expected to feature higher Tg values than E—N copolymers with the same norbomene content and molar mass since polypropene has a higher Tg value than polyethene [66-68]. Moreover, differences in stereo- and regioregularity of propene units as well as in the comonomer distribution and the stereoregularity of the bicyclic units were expected to allow fine tuning of copolymer microstracture and properties. However, compared to E—N copolymers, reports regarding P N copolymers are very limited [94-100]. 

Fig. 6 Sequences observed in the NMR spectra of an isoctatic propene-norbomene copolymer with isolated norbomene units, alternating PNP sequences, and 1,2 ot 2,1 and 13 propene insertions...

Propene-norbomene (P-N) copolymers were exported to feature higher Tg values than E-N copolymers with the same norbomene content and molar mass since polypropene has a... 

Ethene/propene/diene monomer rubbers (EPDM) are elastomeric terpoly-mers used in the production of sealants, tubing and gaskets and, in the USA, is used in roofing applications. As the name suggests they are prepared by the polymerization of mixtures of ethene, propene and diene monomers, to form cross-links. By far the most common diene used is 5-ethylidene-2-norbomene (ENB). 

The results of the olefin oxidation catalyzed by 19, 57, and 59-62 are summarized in Tables VI-VIII. Table VI shows that linear terminal olefins are selectively oxidized to 2-ketones, whereas cyclic olefins (cyclohexene and norbomene) are selectively oxidized to epoxides. Cyclopentene shows exceptional behavior, it is oxidized exclusively to cyclopentanone without any production of epoxypentane. This exception would be brought about by the more restrained and planar pen-tene ring, compared with other larger cyclic nonplanar olefins in Table VI, but the exact reason is not yet known. Linear inner olefin, 2-octene, is oxidized to both 2- and 3-octanones. 2-Methyl-2-butene is oxidized to 3-methyl-2-butanone, while ethyl vinyl ether is oxidized to acetaldehyde and ethyl alcohol. These products were identified by NMR, but could not be quantitatively determined because of the existence of overlapping small peaks in the GC chart. The last reaction corresponds to oxidative hydrolysis of ethyl vinyl ether. Those olefins having bulky (a-methylstyrene, j8-methylstyrene, and allylbenzene) or electon-withdrawing substituents (1-bromo-l-propene, 1-chloro-l-pro-pene, fumalonitrile, acrylonitrile, and methylacrylate) are not oxidized. 

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. 

Copolymers and terpolymers of ethylene and propene, commonly known as EPM and EPDM polymers, respectively, are useful elastomers [Ver Strate, 1986], EPM and EPDM are acronyms for ethylene-propene monomers and ethylene-propene-diene monomers, respectively. The terpolymers contain up to about 4 mol% of a diene such as 5-ethylidene-2-norbomene, dicyclopentadiene, or 1,4-hexadiene. A wide range of products are available, containing 40-90 mol% ethylene. The diene, reacting through one of its double bonds, imparts a pendant double bond to the terpolymer for purposes of subsequent crosslinking (Sec. 9-2b). 

I. Tritto, L. Boggioni, and D.R. Ferro, Metallocene catalyzed ethene-and propene co-norbomene polymerization Mechanisms from a de-... 

While aqueous HF is unreactive towards alkene addition, anhydrous HF is surprisingly reactive. The addition of HF to simple alkenes, such as ethylene, propene and cyclohexene, has been effected by mixing the reagents in an appropriate metal container at temperatures of -78 to -45 °C, and gradually heating the mixture from room temperature to 90 C.7-9 Representative yields are 60-80%. Catalysts are unnecessary. Markovnikov addition is observed, but the stereochemistry of addition to norbomene is not clear.10 With bomylene11 and camphene,12 HF addition gives excellent yields of a mixture of products. 

Acyl isocyanates are more reactive than alkyl or aryl isocyanates. However, the presence of an additional rr-bond conjugated to the C>i-N bond of the isocyanate opens the possibility for [4 + 2] cycloadditions to compete with normal [2 + 2] additions. Reactions with alkyl and aryl substituted alkenes are rather slow. Propene, tranj-2-butene, styrene and conjugated dienes give only 3-lactams, albeit in moderate yields (Scheme 25). The strained double bond of norbomene, a reactive dienophile, adds across the conjugated 4iT-system of trichloroacetyl isocyanate (equation 51). 

Homogeneous vanadium-based catalysts formed by the reaction of vanadium compounds and reducing agents such as organoaluminum compounds [10-12] are used industrially for the production of elastomers by ethylene/propene copolymerization (EP rubber) and ethylene/propene/diene terpolymerization (EPDM rubber). The dienes are usually derivatives of cyclopentadiene such as ethylidene norbomene or dicyclopentadiene. Examples of catalysts are Structures 1-4. Third components such as anisole or halocarbons are used to prevent a decrease in catalyst activity with time which is observed in the simple systems. 

A comonomer for the synthesis of ethylene/propene elastomers - 2-ethylidene-norbomene (7) - is synthesised via a Diels-Alder cycloaddition of cyclopenta-diene and butadiene followed by an isomerization with titanium-based catalysts of the intermediate 2-vinyl derivative 6 in excellent yield (98 %) (eq. (12)) [22]. 

The INS spectra of ethene [23,24] and propene [24] are discussed in 7.3.2.3 and shown in Fig. 7.16. The spectra are dominated by the effects of molecular recoil. This is less of a problem for propene because it has internal vibrations at lower energy (and hence on low-bandpass spectrometers, lower Q) than ethene. With the much heavier tetrabromoethene [25] this does not occur but the small cross section means that a large (8 g) sample was needed. Tetracyanoethene has been studied by coherent INS [26]. The bicyclic alkene norbomene [27] has been studied by INS because it is the parent compound for a class of advanced composites. 

Cyclobutanes from the addition of 1-chloro-l-fluoroethylene to chlorotrifluoro- or tetrafluoro-ethylene, of 2-fluoropropene to tetrafluoroethylene, and of 1-chloro-2,2-difluoroethylene to vinyl fluoride or propene have been claimed to be anaesthetics. Diels-Alder addition of cyclopentadiene to acids of the type, trans-RpCHiCH COaH (Rf = CHaF, CHFa, CFs, C2F5, or n-CsFv) and a number of related esters and other derivatives, at 25 °C, results in predominant formation of adduct witii an endo fluoroalkyl group. The addition of cyclopentadiene to the 1,1-difluoroethylenes, CFalCFa, CFa CF CFs, CFa CCla, CFa C(CF3)2, CFaiCCl-CFaCl, and CFa.CFH has been recorded and the fiee-radical bromina-tion of the resulting norbomenes studied. Buta-1,3-diene and trifluorovinyl-sulphur pentafluoride yield essentially a mbcture of cis- and rmns-cyclobutanes (116), with little or no cyclohexene formation the olefin resembles perfluoropropene which yields ca. 5% of cyclohexene, in this respect. Perfluoroindene, which adds... 

TYPICAL COMONOMERS Ethene, propene, ethylidene norbomene (ENB) or dicyclopentadiene or (DCPD), 1,4 hexadiene (4,4 HD), or vinyl norbomene (VNB) or norbomadiene (NBD). ... 

After Kaminsky, Brintzinger, and Ewen discovered homogeneous metallocene/ methylaluminoxane (MAO) catalysts for stereospecific a-olefin polymerizatiOTi (for reviews on olefin polymerization, see [13-21]), the first report [22, 23] rai addition cycloolefin polymerization without ROMP appeared. This stimulated a great interest in these polymers and in catalysts for cycloolefin polymerization (Fig. 1). Cycloolefins such as cyclopentene, cyclooctene, and norbomene can be polymerized via addition (Fig. 2). Polycycloolefins by metallocenes are difficult to process due to their high melting points and their low solubility in common organic solvents. However, metallocenes allow the synthesis of cyclic olefin copolymers (COC), especially of cyclopentene and norbomene with ethene or propene, which represent a new class of thermoplastic amorphous materials (Scheme 1) [24, 25]. 

Copolymerization of cyclic olefins such as cyclopentene and norbomene with ethene or propene yield cycloolefin copolymers in which the presence of non-cyclic units introduce flexibility in the polymer chain. Thus, the copolymers are amorphous, processable, and soluble in common organic solvents. Early attempts at such copolymerizations were made by using heterogeneous TiCV AlEt2Cl or vanadium catalysts, but real advancements were made utilizing metallocenes and other single-site catalysts, which are about ten times more active than vanadium systems and other Ziegler-Natta catalysts. 

Norbomene can be copolymerized with olefins such as ethene and propene. Among these new cyclic olefin copolymers, made accessible from metallocenes [22, 28, 38-93], the ethene-norbomene (E-N) copolymers are the most versatile and interesting ones. 

The ranges of the reactivity ratios obtained at the lowest [N]/[E] feed ratio are ri = 2.34-4.99 and r2 = 0.0-0.062. The r2 values are in general smaller than those obtained for propene copolymerization. The highest r x 2 values found for the copolymers prepared with catalyst 1-4 confirmed its tendency to give more random copolymers. The values of ri, r2, and ri x r2 for the E-N copolymers obtained with catalysts IV-1 and 1-5 are comparable with those of alternating ethene-propene copolymers with metallocene catalysts. The results of the second-order Markov model also showed that all rn values, as r, are similar to those found for ethene and propene copolymerization with metallocene catalysts with low reactivity ratios. Differences in ri2 and in r22 are illuminating, since they clearly show the preference of the insertion of ethene or norbomene into E-N-Mt (Mt = Metal) and N-N-Mt, respectively. Parameter ri2 increases in the order IV-1 < 1-5 I-l < 1-2, opposite to the tendency to alternate the two comonomers [88]. 

The low activity was demonstrated to result from the difficulty of inserting a propene into the Mt—tertiary carbon bond formed after the norbornene insertion (Mt-N), which is even more sterically crowded than the sites formed after a propene (2,1) regioirregular insertion, less reactive than sites with a primary growing polypropene chain. However, at low norbornene/olefin ratio it is possible to obtain P—N copolymers that are relatively richer in norbomene than the E N copolymers prepared in similar conditions. At higher norbornene/olefin feed ratios, the great amount of 1,3 propene misinsertions clearly revealed that the steric hindrance of the Mt—tertiary carbon bond, when norbomene is the last inserted unit, makes the next propene insertion difficult, causing low polymerization activities, molecular masses, and Tg. 

Kaminsky copolymerized higher condensed cyclic olefin comraiomers such as DMON or TMDA using metallocene catalysts [38, 98]. Low activities in DMON-ethene copolymerization and low incorporation were observed because of the increasing monomer bulk. Although the reactivity ratio for norbomene is similar to that of propene, reactivity ratios for DMON and TMDA are comparable to those of 1-butene and 1-hexene. 

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