Solvent linear alkenes

The p -value for bromination established in methanol is also valid in a variety of other protic solvents. Linear correlations between the bromination rates of unbranched alkenes in methanol and those in a 70-30 methanol-water mixture (M70) [(22) Barbier and Dubois, 1968], in pure water [(23) Bienvenue-Goetz and Dubois, 1968] and in acetic acid [(24) Ruasse and Zhang, 1984) are observed. An approximately linear relationship (25) between... 

This catalyst was also active in hydroformylation of acrylates in supercritical carbon dioxide in this solvent, the rate of hydroformylation of linear alkenes was very low [176],... 

The catalytic properties of post-synthesized PS-Ti-MWW were compared with directly hydrothermally synthesized HTS-Ti-MWW and TS-1 in the epoxidation of 1-hexene with H2O2 (Figure 4.8). For reasonable comparison, the reactions were carried out in the most suitable solvents for the two titanosilicates - in acetonitrile for Ti-MWW and in methanol for TS-1. HTS-Ti-MWW showed much higher intrinsic adivity than TS-1 for 1-hexene. PS-Ti-MWW further proved to be about twice as adive as HTS-Ti-MWW. The efficiency of H2O2 utilization was also very high on PS-Ti-MWW. Thus, in terms of the activity, epoxide selectivity and H2O2 efficiency, PS-Ti-MWW has so far been a most effident heterogeneous catalyst for liquid-phase epoxidation of linear alkenes. 

Bis(diamino)alanes (R2N)2A1H were used for the hydroalumination of terminal and internal alkenes [18, 19]. TiCb and CpjTiCb are suitable catalysts for these reactions, whereas CpjZrCb exhibits low catalytic activity. The hydroaluminations are carried out in benzene or THF soluhon at elevated temperatures (60°C). Internal linear cis- and trans-alkenes are converted into n-alkylalanes via an isomerization process. Cycloalkenes give only moderate yields tri- and tetrasubstituted double bonds are inert. Hydroaluminahon of conjugated dienes like butadiene and 1,3-hexa-diene proceeds with only poor selechvity. The structure of the hydroaluminahon product of 1,5-hexadiene depends on the solvent used. While in benzene cyclization is observed, the reaction carried out in THF yields linear products (Scheme 2-10). 

Fig. 9 Comparison of polar and steric effects of alkyl groups on bromination rates of linear ( ), branched (O) and adamantyl (A) alkenes in acetic acid and in methanol (Ruasse and Zhang, 1984 Ruasse et al., 1990). Polar effects are identical in both solvents [full line, eq. (24)], but steric effects differ. Deviations of branched alkenes are attributed to steric inhibition of nucleophilic solvation by methanol.

Cyclobutanes were also obtained from metallacyclopentanes by simple thermal decomposition, by treatment with other nucleophiles (rather than alkenes) such as phosphanes, nucleophilic solvents or by reaction with oxygen. Byproducts of these reactions are the respective alkenes or linear dimers. The extent of the formation of byproducts depends on the temperature of the decomposition, on the solvent and the nucleophile and on the coordination number of the metal. 

Sulfated zirconia catalysts showed selectivities comparable to those of AICI3 in the alkylation of benzene with 1-alkenes to linear alkylbenzenes.396 The mesopor-ous sulfated zirconia sample could be regenerated by solvent extraction or thermal treatment. Phosphotungstic acid supported on sulfated zirconia doped with Fe proved to be very active and highly selective in the alkylation of benzene with propylene at 100-150°C to produce cumene both monoalkylation and cumene formation have better than 90% selectivity.397 It can be regenerated at moderate temperature (350°C). 

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