60793-36-4Relevant articles and documents
Epoxidation of α,β-unsaturated carbonyl compounds over various titanosilicates
Sasidharan,Wu, Peng,Tatsumi, Takashi
, p. 332 - 338 (2002)
The epoxidation of a variety of electron-deficient α,β-unsaturated carbonyl compounds has been studied using dilute H2O2 and titanium-containing zeolites under liquid-phase conditions. The influence of the reaction medium and the structure of titanium-containing silicates (Ti-β(OH), Ti-Al-β(OH), Ti-β(F), TS-1, TS-2, Ti-MCM-22, and Ti-MCM-41) have been investigated. The weak basic acetonitrile solvent shows better activity and selectivity for epoxide than for other solvents used in this reaction over large-pore zeolite Ti-β. Among the various titanosilicates studied, aluminum-free Ti-β exhibits the best activity and H2O2 selectivity for cyclic α,β-unsaturated ketone, whereas Ti-β and TS-1 exhibit similar activities for open-chain α,β-unsaturated carbonyl compounds. The medium-pore TS-1, TS-2, and Ti-MCM-22 exhibit lower activities for the oxidation of cyclic ketones due to their diffusion limitation. For unsaturated ketones, epoxides are selectively formed, whereas unsaturated aldehydes mainly produce carboxylic acid. Branching at α- and/or β-carbon influences the reactivity of the carbonyl compounds considerably. However, the Ti-β/H2O2 catalytic system fails to oxidize substrates like α,β-unsaturated acids, α,β-unsaturated esters, and isophorone.
Tandem Lewis acid catalysis for the conversion of alkenes to 1,2-diols in the confined space of bifunctional TiSn-Beta zeolite
Lei, Qifeng,Wang, Chang,Dai, Weili,Wu, Guangjun,Guan, Naijia,Hunger, Michael,Li, Landong
, p. 1176 - 1184 (2021/02/16)
The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single-pass tandem catalytic reaction. In this study, bifunctional TiSn-Beta zeolite was prepared by a simple and scalable post-synthesis approach, and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2-diols. The isolated Ti and Sn Lewis acid sites within the TiSn-Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one-step conversion of alkenes to 1,2-diols with a high selectivity of >90%. Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product. Further, the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production.
Green Organocatalytic Dihydroxylation of Alkenes
Theodorou, Alexis,Triandafillidi, Ierasia,Kokotos, Christoforos G.
, p. 1502 - 1509 (2017/04/01)
An inexpensive, green, metal-free one-pot procedure for the dihydroxylation of alkenes is described. H2O2 and 2,2,2-trifluoroacetophenone were employed as the oxidant and organocatalyst, respectively, in this highly sustainable protocol in which a variety of homoallylic alcohols, aminoalkenes, and simple alkenes were converted into the corresponding polyalcohols in good to excellent yields. This process takes advantage of an epoxidation reaction followed by an acidic treatment in which water participates in the ring opening of the in situ prepared epoxide to lead to the desired product.
