4-Penten reaction with ethylene

Pentapyrrolic macrocycles, 2,888 2,1,2-Pen tathiadiazol e-4,7-dicarbonitrile in hydrogen production from water, 6, 508 Pentatungstobis(organophosphonates), 3, 1053 4-Penten-l-al reaction with ethylene catalysts, rhodium complexes, 6, 300... 

The reaction with ethylene and cyclohexene was effected at 350°C or above and that with 1-pentene at 80°C in the presence of benzoyl peroxide. Though the degree of the =SiH group participation in this reaction was not high (3-6% of the =SiH group number) [27], in essence it was the first successful attempt to effect a solid-phase hydrosilylation reaction. 

The required terminal olefins used as substrates for the hydroformylation, such as 1-pentene or 1-octene, are available in large scales and can be derived either from Sasol s Fischer-Tropsch process or from the shell higher olefins process (SHOP), respectively [43, 44]. Alternatively, trimerization or tetramerization of ethylene affords 1-hexene [45] or 1-octene [46]. Dimerization of butadiene in methanol in the presence of a Pd catalyst (telomerization) is another industrially used access for the manufacture of 1-octene [46]. 1-Octene can also be produced on a large scale from 1-heptene via hydroformylation, subsequent hydrogenation, and dehydration (Scheme 6.2) [44]. This three-step homologation route is also valuable for the production of those higher olefins that bear an odd number of C atoms. (X-Olefins can also be derived from internal olefins by cross-metathesis reaction with ethylene [47]. 

A similar method has been developed by Seeberger et al. for metathesis reaction with pentene to give octene-substituted monosaccharide derivatives [373]. In previous solution phase experiments three catalysts were screened at different temperatures and in different solvents which suggest that metathesis proceeds best in dichloromethane at 0°C and with (H2lmes)(3-Br-py)2-(Cl)2Ru = CHPh] as the catalyst. AU soUd phase experiments have been performed on Merrifield octenediol linker 731 and have been checked for the cleavage reaction with ethylene as described in Scheme 109 for the synthesis of terminal olefins. 

The compound (dppe)PtMe(OMe),256 which is prepared by a metathesis reaction involving NaOMe and (dppe)PtMe(Cl) in a mixed benzene/methanol solvent system (dppe = bis(l,2-di-phenylphosphino)ethane), does not react with ethylene or pentene but does react with activated alkenes such as acrylonitrile, methylacrylate and fluoroalkenes. The reaction involving tetrafluoro-ethylene has been shown to give (dppe)PtMe(CF2CF2OMe), providing the first example of an alkene insertion into an M—OR bond.256 Interestingly, no insertion into the Pt—Me bond was observed. 

Studies with ethylene plus 2-butene and with ethylene plus 4-methyl-2-pentene provided additional support for this scheme and demonstrated that disproportionation reactions are reversible. 

The reaction of perfluoro-4-methyl-2-pentene with ethylene glycol also leads to 2-fluoro-2-trifluoromethyl-3-(2,2,2-trifluoro-1 -trifluoromethylethy-lidene)-l,4-dioxane 106 (96ZOB1995). The formation of the six-membered heterocycle occurs via generation of the intermediate carbanion and fluoride ion elimination from the y-position. Subsequent intramolecular nucleophilic cyclization involving the O-nucleophilic center and the internal double bond leads to a 1,4-dioxane derivative (route e). 

In 1980, Miller et al. [76] reported the first example of an intermolecular hydroacylation of an aldehyde with an olefin to give a ketone, during their studies of the mechanism of the rhodium-catalyzed intramolecular cyclization of 4-pentenal using ethylene-saturated chloroform as the solvent. Later James and Young [77] reported that the reaction of propionaldehyde with ethylene can be conducted in the presence of RuCl2(PPh3)3 as the catalyst without any solvent at 210 °C, resulting in the formation of 3-pentanone in 2-4% yield (turnover number of 230) (Eq. 49). 

Isomerization from the secondary to the more stable tertiary carbonium ion precedes reaction with the next molecule of monomer. A 1,3 polymerization has therefore occurred. Similarly, 4-methyl-l-pentene gives a 1,4 polymer (probably involving two successive 1,2 hydride shifts) that has a structure corresponding to an ethylene-isobutylene copolymer (Reaction 25). 

Several non-polymerizable olefins have been successfully co-polymerized with ethylene, the most successful results being achieved with the r -Cp-amido catalysts. Relevant cases are those of isobutene,260 2-methyl-l-pentene,593 and 2-butene. Typical C2- and ( -symmetric metallocenes like 29 and 32 have been reported to selectively co-polymerize ethylene with as- and /ra r-2-butene, respectively. Working at low ethylene concentration, up to 25% and 14% mol of butene could be incorporated into the co-polymers obtained with 29 and 32, respectively. Independent of the symmetry of the catalyst, the inserted 2-butene units undergo chain-isomerization reactions that lead to isolated methyl groups in the case of trans-2-butene co-polymerization, and to mainly isolated ethyl groups and a minor amount of isolated methyl groups in the case of nr-2-butene insertion, as shown in Scheme 24.594,595... 

METHYL-3-PENTENE-2-ONE (141-79-7) Forms explosive mixture with air (flash point 87°F/31°C). Forms unstable peroxides in storage. Violent reaction with strong oxidizers, 2-aminoethanol, chlorosulfonic acid, 1,2-ethanediamine, ethanolaraine, nitric acid, sulfuric acid, oleum. Incompatible with strong acids aliphatic amines, alkanolamines, ethylene diamine. Dissolves some forms of plastics, resins, and rubber. Attacks copper. 

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