ChemInform Abstract: DISPROPORTIONATION OF HALOOLEFINS

Fridman, R. A.; Bashkirov, A.N.; Liberov, L. G.; Nosakova, L. M.; Smirnova, R.M.; Verbovetskaya, S. B.

doi:10.1002/chin.197748092

Cited by 3 publications

(4 citation statements)

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“…A tungsten dichlorocarbene complex [W]=CCl 2 has also been proposed as an active species in the W(CO) 6 /CCl 4 / hν catalyst system 9. To our knowledge, there has been only one report of metathesis involving directly halogenated olefins, namely the cross metathesis of 1‐chloro‐ and 1‐bromoethylene with propylene using Re 2 O 7 /Al 2 O 3 /Me 4 Sn 6e. Herein, we report the successful metathesis of 1,1‐difluoroethylene with ruthenium catalyst 1 .…”

Section: Romp Of Cod With Catalysts 1–3[a]mentioning

confidence: 93%

Olefin Metathesis with 1,1-Difluoroethylene

2001

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The recent development of ruthenium olefin-metathesis catalysts coordinated with N-heterocyclic carbene ligands is a significant advance because it extends the scope of the reaction to more challenging substrates, that is, those that are sterically hindered or that contain electronically deactivating groups, as well as monomers with low ring strain. [1±4] One set of substrates that has received relatively little attention, however, is the halogenated olefins; [5] the metathesis of allyl bromide, allyl chloride, and related substrates with the heterogeneous Re 2 O 7 /Al 2 O 3 /Me 4 Sn catalyst system are among the few examples. [6] Most recently, the cross metathesis of 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexene with terminal olefin [4c] and the dimerization of vinyl gem-difluorocyclopropane derivatives [7] have been achieved using [(H 2 IMes)-(PCy 3 )(Cl) 2 RuCHPh] (1) (H 2 IMes 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene; Cy cyclohexyl). In these cases, the substrates are challenging because of the electron-withdrawing nature of the pendent halogens.A particularly interesting situation arises when the olefin is directly halogenated, because then the metathesis reaction will involve a monohalo [M] CXR or dihalo [M] CX 2 carbene complex rather than the usual alkylidene [M] CR 2 . This possibility has been considered by Beauchamp and coworkers, who have speculated about the metathesis of directly fluorinated olefins with nickel or manganese complexes. [8] A tungsten dichlorocarbene complex [W]CCl 2 has also been proposed as an active species in the W(CO) 6 /CCl 4 /hn catalyst system. [9] To our knowledge, there has been only one report of metathesis involving directly halogenated olefins, namely the cross metathesis of 1-chloro-and 1-bromoethylene with propylene using Re 2 O 7 /Al 2 O 3 /Me 4 Sn. [6e] Herein, we report the successful metathesis of 1,1-difluoroethylene with ruthenium catalyst 1.Under an atmosphere of 1,1-difluoroethylene, 1 reacts to form the corresponding methylidene [(H 2 IMes)(PCy 3 )-(Cl) 2 RuCH 2 ] (2) [10] and difluorocarbene [(H 2 IMes)-(PCy 3 )(Cl) 2 Ru CF 2 ] (3) complexes [Eq. (1)]. [11] When the reaction is performed at room temperature, the product mixture contains approximately 40 % methylidene (2) and 60 % difluorocarbene (3), as well as styrene and b,b-

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Section: Romp Of Cod With Catalysts 1–3[a]mentioning

confidence: 93%

Olefin Metathesis with 1,1-Difluoroethylene

2001

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“…CHz=CHz CH z CH z + ~ I I + II (53) COz=COz CO z CO2 catalysed by Re 2 0 7 /y-AI 2 0 3 • They observed that pretreatment of the catalyst with a higher alkene, e.g. propene, highly improves the catalytic activity.…”

Section: Initiation and Terminationmentioning

confidence: 96%

“…Halogen-containing alkenes also undergo metathesis. Even vinyl halides can be transformed into their metathesis products [53]: 2 CH2 =CH-CI ~ CHz=CHz + CI-CH=CH-CI (27) Silicon-containing alkenes react as easily as simple alkenes, obviously because of the carbon-like chemical behaviour of this hetero-atom [54]; alkenes containing both silicon and oxygen can also undergo metathesis [55].…”

Section: Functionalized Alkenesmentioning

confidence: 99%

Catalytic Metathesis of Alkenes

Mol

Moulijn

1987

Catalysis

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“…A further enhancement in activity of the rheniumbased catalyst by a factor of 5-10 can be obtained by adding a tetraalkyltin promoter [78,94,102]. When promoted with a small amount of a tetraalkyltin (R 4 Sn, R = Me, Et or Bu) or a tetraalkyllead (R 4 Sn, R = Et or Bu) compound, all of these modified catalysts bring about the metathesis of alkenes containing functional groups (e.g.…”

Section: Modified Re 2 O 7 /Al 2 O 3 Catalystsmentioning

confidence: 99%

Metathesis of Alkenes

Mol

Leeuwen

2008

Handbook of Heterogeneous Catalysis

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The sections in this article are Introduction Scope of the Reaction Acyclic Alkenes Alkadienes Cyclic Alkenes Ring‐Opening Metathesis Metathesis Catalysts Solid Metathesis Catalysts Mechanism Molybdenum Catalysts Mo O 3 / Al 2 O 3 Effect of Impurities Mo O 3 / Si O 2 Tungsten Catalysts WO 3 / Al 2 O 3 WO 3 / Si O 2 Rhenium Re 2 O 7 / Al 2 O 3 A Catalyst Characterization B Particle Size C Catalytic Activity D Selectivity Modified Re 2 O 7 / Al 2 O 3 Catalysts A Role of the Promoter B Catalyst Deactivation Kinetics Industrial Applications The P hillips T riolefin Process The Meta‐4 Process Production of 1‐Hexene Production of Neohexene SHOP Production of Fine Chemicals Conclusions

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ChemInform Abstract: DISPROPORTIONATION OF HALOOLEFINS

Abstract: Halogenolefine werden durch Rheniumoxid/Aluminiumoxid allein nicht disproportioniert, da der Katalysator sofort inaktiviert wird.

Cited by 3 publications

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Olefin Metathesis with 1,1-Difluoroethylene

Olefin Metathesis with 1,1-Difluoroethylene

Catalytic Metathesis of Alkenes

Metathesis of Alkenes

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