60793-36-4

Upstream product

• 6705-49-3 7-oxabicyclo[4.1.0]heptan-2-one 
• 6705-49-3 7-oxabicyclo[4.1.0]heptan-2-one 
• 110-83-8 cyclohexene 
• 930-68-7 cyclohexenone 
• 6286-43-7 1,2,3-trihydroxycyclohexane 

Downstream Products

• 5011-76-7 2-acetoxy-2-cyclohexen-1-one 
• 3400-88-2 2-chlorocyclohex-2-en-1-one 

Relevant academic research and scientific papers

Epoxidation of α,β-unsaturated carbonyl compounds over various titanosilicates

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

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.

Activation of H2O2over Zr(IV). Insights from Model Studies on Zr-Monosubstituted Lindqvist Tungstates

Zr-monosubstituted Lindqvist-type polyoxometalates (Zr-POMs), (Bu4N)2[W5O18Zr(H2O)3] (1) and (Bu4N)6[{W5O18Zr(μ-OH)}2] (2), have been employed as molecular models to unravel the mechanism of hydrogen peroxide activation over Zr(IV) sites. Compounds 1 and 2 are hydrolytically stable and catalyze the epoxidation of C?C bonds in unfunctionalized alkenes and α,β-unsaturated ketones, as well as sulfoxidation of thioethers. Monomer 1 is more active than dimer 2. Acid additives greatly accelerate the oxygenation reactions and increase oxidant utilization efficiency up to >99%. Product distributions are indicative of a heterolytic oxygen transfer mechanism that involves electrophilic oxidizing species formed upon the interaction of Zr-POM and H2O2. The interaction of 1 and 2 with H2O2 and the resulting peroxo derivatives have been investigated by UV-vis, FTIR, Raman spectroscopy, HR-ESI-MS, and combined HPLC-ICP-atomic emission spectroscopy techniques. The interaction between an 17O-enriched dimer, (Bu4N)6[{W5O18Zr(μ-OCH3)}2] (2′), and H2O2 was also analyzed by 17O NMR spectroscopy. Combining these experimental studies with DFT calculations suggested the existence of dimeric peroxo species [(μ-?2:?2-O2){ZrW5O18}2]6- as well as monomeric Zr-hydroperoxo [W5O18Zr(?2-OOH)]3- and Zr-peroxo [HW5O18Zr(?2-O2)]3- species. Reactivity studies revealed that the dimeric peroxo is inert toward alkenes but is able to transfer oxygen atoms to thioethers, while the monomeric peroxo intermediate is capable of epoxidizing C?C bonds. DFT analysis of the reaction mechanism identifies the monomeric Zr-hydroperoxo intermediate as the real epoxidizing species and the corresponding α-oxygen transfer to the substrate as the rate-determining step. The calculations also showed that protonation of Zr-POM significantly reduces the free-energy barrier of the key oxygen-transfer step because of the greater electrophilicity of the catalyst and that dimeric species hampers the approach of alkene substrates due to steric repulsions reducing its reactivity. The improved performance of the Zr(IV) catalyst relative to Ti(IV) and Nb(V) catalysts is respectively due to a flexible coordination environment and a low tendency to form energy deep-well and low-reactive Zr-peroxo intermediates.

Green Organocatalytic Dihydroxylation of Alkenes

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.

Mechanistically Driven Development of an Iron Catalyst for Selective Syn-Dihydroxylation of Alkenes with Aqueous Hydrogen Peroxide

Product release is the rate-determining step in the arene syn-dihydroxylation reaction taking place at Rieske oxygenase enzymes and is regarded as a difficult problem to be resolved in the design of iron catalysts for olefin syn-dihydroxylation with potential utility in organic synthesis. Toward this end, in this work a novel catalyst bearing a sterically encumbered tetradentate ligand based in the tpa (tpa = tris(2-methylpyridyl)amine) scaffold, [FeII(CF3SO3)2(5-tips3tpa)], 1 has been designed. The steric demand of the ligand was envisioned as a key element to support a high catalytic activity by isolating the metal center, preventing bimolecular decomposition paths and facilitating product release. In synergistic combination with a Lewis acid that helps sequestering the product, 1 provides good to excellent yields of diol products (up to 97% isolated yield), in short reaction times under mild experimental conditions using a slight excess (1.5 equiv) of aqueous hydrogen peroxide, from the oxidation of a broad range of olefins. Predictable site selective syn-dihydroxylation of diolefins is shown. The encumbered nature of the ligand also provides a unique tool that has been used in combination with isotopic analysis to define the nature of the active species and the mechanism of activation of H2O2. Furthermore, 1 is shown to be a competent synthetic tool for preparing O-labeled diols using water as oxygen source.

Olefin cis-Dihydroxylation and Aliphatic C-H Bond Oxygenation by a Dioxygen-Derived Electrophilic Iron-Oxygen Oxidant

Many iron-containing enzymes involve metal-oxygen oxidants to carry out O2-dependent transformation reactions. However, the selective oxidation of C-H and C-C bonds by biomimetic complexes using O2 remains a major challenge in bioinspired catalysis. The reactivity of iron-oxygen oxidants generated from an FeII-benzilate complex of a facial N3 ligand were thus investigated. The complex reacted with O2 to form a nucleophilic oxidant, whereas an electrophilic oxidant, intercepted by external substrates, was generated in the presence of a Lewis acid. Based on the mechanistic studies, a nucleophilic FeII-hydroperoxo species is proposed to form from the benzilate complex, which undergoes heterolytic O-O bond cleavage in the presence of a Lewis acid to generate an FeIV-oxo-hydroxo oxidant. The electrophilic iron-oxygen oxidant selectively oxidizes sulfides to sulfoxides, alkenes to cis-diols, and it hydroxylates the C-H bonds of alkanes, including that of cyclohexane. Lewis acid mediated O-O bond cleavage: A nucleophilic iron(II)-hydroperoxo oxidant, formed upon oxidative decarboxylation of an iron(II)-α-hydroxy acid complex, undergoes heterolytic O-O bond cleavage in the presence of a Lewis acid to generate an electrophilic iron(IV)-oxo-hydroxo oxidant. The electrophilic oxidant oxidizes sulfides to sulfoxides and alkenes to cis-diols, and it hydroxylates the strong C-H bonds of aliphatic substrates.

A facile synthesis of vicinal cis-diols from olefins catalyzed by in situ generated MnxOy nanoaggregates

A novel protocol for the practical and green synthesis of vicinal cis-diols from 10.0 mmol olefins by using 5.0 mmol KMnO4 as oxidant and 30.0 mmol H2O2 as co-oxidant is reported. The presented procedure is easy to carry out and enables the direct transformation of linear and cyclic alkenes to the corresponding vicinal cis-diols. The synthesis of vicinal cis-diols by dihydroxylation of olefins with a KMnO4/H2O2 system was catalyzed by in situ generated MnxOy nanoaggregates. The use of H2O2 as a co-oxidant is the key for the protocol to synthesize vicinal cis-diols in high yields, because it assists the oxidation of MnxOy nanoaggregates, which have an active role in the oxidation reaction medium.

A procedure for the preparation of Ti-Beta zeolites for catalytic epoxidation with hydrogen peroxide

Ti-Beta zeolite has been successfully prepared via a reproducible and scalable two-step post-synthesis strategy, which consists of creating vacant T sites with associated silanol groups by dealumination of H-Beta and subsequent dry impregnation of the resulting Si-Beta with titanocene dichloride. The mechanism of Ti incorporation into the framework of Beta is investigated by diffuse reflectance infrared Fourier transform (DRIFT) and multinuclear solid-state nuclear magnetic resonance (SSNMR) spectroscopy. Characterization results obtained from diffuse reflectance ultraviolet-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS) reveal that the majority of incorporated Ti species exist in the form of isolated tetrahedrally coordinated Ti(iv) in the zeolite framework while a minority exists in the form of isolated octahedrally coordinated Ti(vi) at framework or extra-framework positions. The obtained Ti-Beta zeolites are highly active and selective catalysts for the epoxidation of unsaturated ketones, e.g. 2-cyclohexen-1-one, with hydrogen peroxide as an oxidant. A quasilinear correlation between the epoxidation rate and the number of framework Ti(iv) species could be drawn evidencing that these Ti(iv) species are responsible for the epoxidation activity of the Ti-Beta zeolites under study. The impact of preparation parameters and reaction conditions on the catalytic performances of the Ti-Beta zeolites in the epoxidation of unsaturated organic compounds with hydrogen peroxide is discussed in detail. the Partner Organisations 2014.

Reactivity of C-H bonds in cyclohexanone and 1-tert-butylperoxycyclohexanol toward the tert-butylperoxyl radical

The kinetics of oxygen uptake and the composition of the cyclohexanone oxidation products in the azobisisobutyronitrile-initiated oxidation of cyclohexanone in the presence of tert-butyl hydroperoxide have been investigated by the Howard-Ingold method. The partial rate constants of the reaction of the tert-butylperoxyl radical with the C-H bonds of cyclohexanol and 1-tert-butylperoxycyclohexanole at 333 K have been determined. The carbonyl group of cyclohexanone activates the C-H bonds in the 2- and 6-positions (α) and deactivates the C-H bonds in the 3- and 5-positions (β) compared to the C-H bonds in the 4-position (γ), whose reactivity is similar to that of the methylenic C-H bonds in cyclohexane. Evaluation of the joint effect of the hydroxyl and tert-butylperoxyl groups in 1-tert-butylperoxycyclohexanol suggests a considerable deactivation of the C-H bonds in the 2- and 6-positions (β) and, to a lesser extent, in the 3- and 5-positions (γ).

Hot water-promoted ring-opening of epoxides and aziridines by water and other nucleopliles

Effective hydrolysis of epoxides and aziridines was conducted by heating them in water at 60 or 100 °C. Other types of nucleophile such as amines, sodium azide, and thiophenol could also efficiently open epoxides and aziridines in hot water. It was proposed that hot water acted as a modest acid catalyst, reactant, and solvent in the hydrolysis reactions.