10353-53-4Relevant academic research and scientific papers
The selective epoxidation of conjugated olefins containing allylic substituents and epoxidation of propylene in the presence of butadiene
Monnier, John R.,Peters, Kimberly T.,Hartley, Gary W.
, p. 374 - 380 (2004)
The epoxidation of isoprene (2-methyl-1,3-butadiene) and piperylene (1,3-pentadiene), both conjugated olefins containing allylic methyl groups, has been conducted using conventional, CsCl-promoted, Ag/α-Al 2O3 catalysts. Selectivities to the allylic olefin epoxide isomers are over 20% and are much higher than expected due to the presence of the conjugated olefin structure. The epoxidation of propylene over the same catalyst under the same conditions is only 2.5%. The epoxidation of propylene in the presence of butadiene also yields PO in much higher selectivities. The presence of as little as 1% C4H6 in the reaction feedstream increases the selectivity to PO from 2.5% to over 40% at the expense of overall activity for C3H6 conversion. The upper limit of selectivity to PO in the presence of C4H6 appears to be approximately 50%, suggesting an upper limit for the effectiveness of this methodology. Epoxidation of C4H6 alone on similar Ag catalysts indicates that the consecutive reaction of EpB to CO 2/H2O is strongly limited by the presence of excess C 4H6 in the feedstream. In addition, the selectivity to EpB is directly proportional to the amount of C4H6 in the reaction feed stream. Selectivities >90% are obtained only when there is sufficient C4H6 in the reaction feedstream to control the concentration of the reactive Ag-O surface. For C4H6 epoxidation, all CO2/H2O is formed by a consecutive reaction pathway from EpB; there is no parallel pathway for the direct formation of CO2/H2O from C4H6. Using the selective epoxidation of C4H6 as the model for understanding the enhancement in selectivity for allylic olefin epoxide formation, the most likely reason for improved selectivities is that strongly adsorbed C4H6 (or other conjugated olefins) limits the ensemble size of contiguous Ag-O surface sites. These ensembles are too small for PO combustion, but not too small for PO formation.
Bioproduction of chiral epoxyalkanes using styrene monooxygenase from rhodococcus sp. ST-10 (RhSMO)
Toda, Hiroshi,Imae, Ryouta,Itoh, Nobuya
, p. 3443 - 3450 (2015/02/05)
We describe the enantioselective epoxidation of straight-chain aliphatic alkenes using a biocatalytic system containing styrene monooxygenase from Rhodococcus sp. ST-10 and alcohol dehydrogenase from Leifsonia sp. S749. The biocatalyzed enantiomeric epoxidation of 1-hexene to (S)-1,2-epoxyhexane (44.6 mM) using 2-propanol as the hydrogen donor was achieved under optimized conditions. The biocatalyst had broad substrate specificity for various aliphatic alkenes, including terminal, internal, unfunctionalized, and di- and tri-substituted alkenes. Here, we demonstrate that this biocatalytic system is suitable for the efficient production of enantioenriched (S)-epoxyalkanes.
Regioselective epoxidation of different types of double bonds over large-pore titanium silicate Ti-β
Sasidharan, Manickam,Bhaumik, Asim
experimental part, p. 60 - 67 (2010/12/18)
Regioselective epoxidation of different types of double bonds located within the cyclic and acyclic parts of bulky olefins has been investigated using large-pore titanium silicate Ti-β in the presence of dilute aqueous H 2O2 as oxidant under mild liquid-phase conditions. Our experimental results revealed that side-chain vinylic double bonds are selectively epoxidized than those in the cyclohexene-ring. The epoxidation tendency of various bulky olefins with different positional and/or geometric isomers over Ti-β follows the order: terminal -CC- > ring -CC- ≈ bicyclic ring -CC- > allylic C - H bond. Unlike 4-vinyl-1-cyclohexene, epoxidation of an equimolar mixture of cyclohexene and 1-hexene under identical conditions using Ti-β exhibits completely different selectivity and product distributions. Steric factor and accessibility of reactants to active Ti-sites are responsible for the observed regioselectivity of bulky alkenes.
C2-bridged metallocene dichloride complexes of the types (C13H8-CH2CHR-C9H 6-nR′n)ZrCl2 and (C13H8-CH2CHR-C13H 8)MCl2 (n=0, 1; R=H, alkenyl; R′=alkenyl, benzyl; M=Zr, Hf) as self-immobilizing catalyst precursors for ethylene polymerization
Alt, Helmut G.,Jung, Michael
, p. 1 - 16 (2007/10/03)
A total of 15 C2-bridged fluorenylidene indenylidene and bis(fluorenylidene) metal dichloride complexes (metal=Zr, Hf) and the corresponding ligand precursors have been prepared and characterized. ω-Alkenyl substituents with various chain lengths in the C2-bridge or in position 3 of the indenylidene moiety have an impact on the polymerization activity of the catalysts and the molecular weights of the produced polyethylenes. These ω-alkenyl substituents cause 'self-immobilization' due to their incorporation into the backbone of a growing polymer chain providing heterogeneous catalyst systems.
Lewis Acid Promoted Ring-Opening Allylation of Epichlorohydrin with Allylic Silanes and Stannanes To Afford 1-Chloro-5-alken-2-ols. A Short Synthesis of (S)-(-)-Ipsenol
Imai, Toshiro,Nishida, Shinya
, p. 4849 - 4852 (2007/10/02)
Epichlorohydrine (1) was allylated in good yields with representative allylic silanes (2, 5, 7, 9) and stannanes (12, 18) in the presence of appropriate Lewis acids.The reaction proceeds with ring opening at the unsubstituted site in 1 and with allylic inversion in the allylating agents to give 1-chloro-5-alken-2-ols cleanly.A short synthesis of (S)-(-)-ipsenol (29) from 1 and an (allenylmethyl)silane (26) demonstrates the utility of this method in organic synthesis.
Synthesis and Insecticidal Activity of Oxazaphospholidines, Oxathiaphospholanes, and Thiazaphospholidines
Wu, Shao-Yong,Hirashima, Akinori,Takeya, Ryuko,Eto, Morifusa
, p. 2911 - 2918 (2007/10/02)
Fifty-five new five-membered cyclic organophosphorus compounds including oazaphospholidines, thiazaphospholidines, and oxathiaphospholanes were synthesized, which have substituents at 4- or/and 5-positions besides at the 2-position.The thiazaphospholidines showed the highest insecticidal activity followed by oxathiaphospholanes and oxazaphospholidines.The position preference of substituents in insecticidal activity was most obvious in the oxazaphospholidines.It was preferable for insecticidal activity to have the substituent near the more basic atom: the 4-position for thiazaphospholidine and oxazaphospholidine, the 5-position for oxathiaphospholane, with the exception of 4- or 5-phenyl oxazaphospholidine.
Synthesis of Cyclic Ethers via Bromine Assisted Epoxide Ring Expansion
Davies, Stephen G.,Polywka, Mario E. C.,Thomas, Susan E.
, p. 1277 - 1282 (2007/10/02)
Neighbouring group participation by epoxide oxygen in the opening of bromonium ions results in the stereoselective synthesis of cyclic ethers. 9-Oxabicyclonon-4-ene gives trans, trans-2,6-dibromo-9-oxabicyclononane and trans,trans-2,5-dibromo-9-oxabicyclononane.Sequential bromination and Bu3SnH reduction converts 1,2-epoxyhex-5-ene into cis- and trans-2,5-dimethyltetrahydrofuran and 2-methyltetrahydropyran while (+)-cis-limonene oxide is converted into non-chiral cineole.
