Cycloolefin conversions

Concerning cometathesis of cycloolefins with a-olefins, practically there is no information in the literature about stereo-specificity. One of few studies in this field has given 1,9-tetradecadiene stereo-content Z/E = 45/55 which has been achieved by cometathesis of Z-cyclooctene with a-hexene in the presence of WCl6/EtOH/EtAlCl2 at 25 C and 70 % cycloolefin conversion [25]. 

For example, the selectivities of l,A-dienes formation as high as 57-86% has been achieved when the reaction was carried out at 4 C, with five-fold excess of a-olefins and at cycloolefin conversion of < 85% (Table 1). Cometathesis products contain up to 79% of Z-isomers. Selectivities of all types drop when the cycloolefin conversion increases (Table 1). 1,A-Dienes 3 a-g (Scheme 1) were isolated from the final mixtures and were used for preparation of insect sex pheromone components. Synthesis of... 

Cyclodecene did not display any tendency to form the dienes having predominantly cis double bonds independently from a-olefin length. Even at low cycloolefin conversion, content of Z-11-dienes did not exceed 24% (Table 1), that is close to the thermodynamical equilibrium value typical for metathesis and cometathesis of linear olefins. At the same time, there are a great number of commercially important pheromones containing structures with Z double bond in the 11-position as the main... 

Conventional processes for preparing COCs have some common problems. The conversion of the cycloolefin may be low and further, a high amount of ethylene incorporated results in unsatisfactory low glass transition temperatures. Catalyst compositions have been developed in order to obtain materials with high glass transition temperatures (26). Examples are shown in Table 2.3. These catalysts are used for the copolymerization of ethene and norbornene. 

Reactions with Hydrogen The mild acid nature of the family of aluminophosphate-based sieves renders them selective for a number of rearrangements, as observed in the reactions of olefins and paraffins described previously. This selectivity as well as their apparent low disproportionation activity observed in the alkylation of toluene suggests that the aluminophosphate-based sieves be evaluated as the acid function in bifunctional Cg aromatic isomerization. As described previously, cycloolefins are most likely involved in the conversion of ethylbenzene to xylenes. Strong acid functions, such as in mordenite, actively isomerize cyclo-olefinic intermediates but also catalyze ring-opening reactions, which lead to loss of aromatics. A more selective acid function must effectively interconvert ethylcyclohexene to dimethylcyclohexenes but must leave the cyclohexene rings intact. 

Poly(norbornene Sulfones) by Radical Polymerization. Cycloolefins such as norbomene copolymerize with SO2 in an alternating fashion by radical initiation at room temperature or even at 50 °C, reflecting their high ceiling temperatures (77). In order to avoid the use of a pressure bottle, however, we carried out the polymerization of norbomenes with SO2 at cryogenic temperatures. A partial list of poly(norbomene sulfones) we prepared is presented in Scheme V. All the polymers were prepared readily in high conversions but some of the polymers were not very soluble (pendant carboxylic acid, for example). This paper primarily discusses about the... 

On the other hand, ROMP can be used to obtain polymers, containin very high content of Z-double bonds depending on type of catalyst system and polymerization conditions at high conversions of cycloolefins C5 [19-21] C7 [22] and Cs [22-23]. This dramatically differentiates the ROMP from metathesis of linear olefins. In 1978 N. Calderon wrote this phenomenon may be due to multiple oordination of the polymer chain, which can not occur in the reaction of acyclic olefin [24]. 

We have observed that the stereo-content of 1,11-dienes obtained by cometathesis of Z-cyclodecene with a-olefins is dramatically different from dienes realized from the other studied cycloolefins of lower ring size. The stereo-content of 1,11-dienes turned out to be close to equilibrium even at rather low conversions (Table 3). In the case of cyclopentene,... 

In the cases of cycloolefins C7-C9, thermodynamic equilibrium concentration values have been achieved at 98-100 % conversions. At the same time, for Z-cyclodecene the stereocontent was close to thermodynamic equilibrium even at 3 % conversion. 

When using the cyclopentene as a starting cycloolefin, equilibrium stereo-content of cometathesis products is achieved at incomplete cyclopentene conversion. Equilibrium concentration of 1,6E-undecadiene is 86 % and of 1,6E,1 lE-hexadecatriene (the product of double insertion of cyclopentene into 1-hexene) - 87 %. At the same time, in the case of initial C7-C10 cycloolefins thermodynamically equilibrium values for corresponding 1,AE-dienes (A= 8-11) are 84 % and for corresponding 1,(8-11)E,( 15-21 )E-trienes are 78 % (Table 2). 

Table 3 demonstrates our data on reaction product stereo-contents measured at the initial olefin conversion 22 %, that is to say, far from equilibrium. At this conversion Z-isomers are predominant, when using cycloolefins C5, and C7-C9. However, among them Z-isomer contribution is the least for cyclopentene cometathesis. Probably these facts are connected... 

The thermal polymerization of butadiene yields, according to Ziegler et al., a mixture of vinylcyclohexene with at most 15% of cyclooctadiene (95, 96). In 1954 Reed (97) discovered the catalytic cyclodimerization of butadiene to cycloocta-1,5-diene with Reppe catalysts, with a 30-40% conversion at 120-130° C. Wilke et al. recently synthesized a very efficient class of catalyst. If nickel-acetylacetonate is treated with metal alkyls (especially aluminum alkyls) in the presence of electron-donating compounds (mainly cycloolefins), new tt complexes of nickel are obtained which catalyze the cyclo-oligomerization of butadiene (98, 99). Using cycloocta-1,5-diene as the olefinic component, the well-crystallized, faintly yellow bis(cycloocta-... 

Concentrated sulphuric acid has been initially used for dimerization and oligomerization of cyclic monoolefins such as cyclohexene and diolefins such as cyclo-pentadiene, and later on for indene-coumarone fractions. Diluted sulphuric acid and benezenesulpho-nic acid have been further employed for the polymerization of more active cycloolefins like norbornene and dicyclopentadiene. In these reactions, monomer conversion, product yield and molecular mass depended largely on the acid concentration and monomer nature as well as on the other reaction parameters. Various compositions of initiators containing sulphuric acid in association with phosphoric acid, boric acid, sulphonic acids or inorganic sulphates of the type M (S04) (M = Al, Cr, Mg, Co, V) have also been reported for the polymerization of unsaturated alicyclic and cyclic fractions and for reactions with heavy aromatic fractions in hydrocarbon resin synthesis [2]. 

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