Catalytic alkenes. Medical search. Frequent questions

However, it is difficult to find a method as efficient as oxidation for cleaving C-C bonds, especially the bonds of alkenes and alkynes. (nature.com)
The physical properties of alkenes and alkynes are generally similar to those of alkanes or cycloalkanes with equal numbers of carbon atoms. (britannica.com)
that of alkenes and alkynes is addition to the double or triple bond . (britannica.com)
The in situ generated electrophilic carbene reacts smoothly with a broad range of alkenes and alkynes to provide the corresponding difluorocyclopropanes and difluorocyclopropenes within 10 min residence time at high reaction concentrations. (organic-chemistry.org)
An article based on the study, " Isolated, Well-Defined Organovanadium(III) on Silica: Single-Site Catalyst for Hydrogenation of Alkenes and Alkynes ," appeared online in Chemical Communications on May 9 in the special issue, "ChemComm's 2017 Emerging Investigators. (newswise.com)

1,1-Disubstituted alkenes are a challenging class of substrates for the asymmetric hydroboration reaction. (unl.edu)
Following the initial development of a method for the catalytic asymmetric cyclopropanation of alkenes using nitro diazoketones, many experimental studies on the mechanism of stereoinduction in this reaction were performed. (umontreal.ca)

Ti atoms incorporated into the framework of zeolite *BEA (Ti-BEA) or grafted onto SBA-15 (Ti-SBA-15) catalyze alkene epoxidation with hydrogen peroxide (H2O2), t-butyl hydrogen peroxide (TBHP), or cumene hydroperoxide (CHP). (illinois.edu)
The rates of epoxidation, however, differ by orders of magnitude depending on the combination of an oxidant, an alkene, and a support used. (illinois.edu)
Second, differences in the epoxidation rates between Ti-BEA and Ti-SBA-15 largely reflect the changes in the stability of the alkenes adsorbed within the pores of each silicate. (illinois.edu)
Third, the distinct sensitivities of epoxidation rates on oxidant identity within Ti-BEA and Ti-SBA-15 are caused by differences between the inner-sphere interactions among Ti-OOR intermediates and adsorbed alkenes that depend on the surrounding environment. (illinois.edu)
Catalytic epoxidation of alkenes by the manganese complex of a reduced porphyrinogen macrocycle Adv. Synth. (nottingham.ac.uk)
There has been considerable effort to develop alternative alkene epoxidation methods by employing an oxidant such as tert-butyl hydroperoxide (TBHP) as it is environmentally benign, safer to handle and possesses good solubility in polar solvents. (lancs.ac.uk)
A notable industrial implementation of alkene epoxidation with TBHP was the Halcon process that employed soluble molybdenum(VI) as a catalyst for liquid phase epoxidation of propylene to propylene oxide. (lancs.ac.uk)
However, homogenous catalysed alkene epoxidation has several drawbacks including deposition of catalyst on the reactor walls and increased difficulties in separation of catalyst from the reaction mixture. (lancs.ac.uk)
Furthermore, the efficiency of the heterogeneous catalyst for continuous epoxidation studies have been assessed using a FlowSyn continuous flow reactor by studying the effect of reaction temperature, feed molar ratio of alkene to TBHP and feed flow rate on the conversion of the oxidant and the yield of corresponding epoxide. (lancs.ac.uk)

These include dual catalytic approaches, reactions involving other metals, and mechanistically distinct palladium-catalyzed methods. (wikipedia.org)
Non-Noble Metal Catalysis: Molecular Approaches and Reactions is an indispensable source of up-to-date information for catalytic chemists, organic chemists, industrial chemists, organometallic chemists, and those seeking to broaden their knowledge of catalytic chemistry. (wiley-vch.de)
I completed my PhD in Neuchâtel (Switzerland) in 2008, working on the development of enantioselective catalytic reactions by using artificial metalloenzymes, with Prof. Thomas R. Ward. (nottingham.ac.uk)
The transition-metal-catalysed hydrosilylation reaction of alkenes is one of the most important catalytic reactions in the silicon industry. (nature.com)
The present study explored the effects of HAP crystal orientation in methane oxidation reactions, which revealed distinct catalytic behaviors of crystal surfaces in HAP-based materials. (osti.gov)
Replacement of Pd/C by powdered catalytic converter for hydrogenation reactions. (sciencemadness.org)
Sciencemadness Discussion Board » Fundamentals » Organic Chemistry » Replacement of Pd/C by powdered catalytic converter for hydrogenation reactions. (sciencemadness.org)
Subject: Replacement of Pd/C by powdered catalytic converter for hydrogenation reactions. (sciencemadness.org)
Replacement of Palladium on carbon by powdered catalytic converter for hydrogenation reactions. (sciencemadness.org)
The goal of these post is to report on the efficacy on the replacement of palladium on carbon by powdered catalytic converters from cars for 3 reactions. (sciencemadness.org)
Many reactions of alkenes are initiated by hydroboration , then conversion of the resulting alkyl borane. (organic-chemistry.org)
His research interests lie in the design and mechanistic understanding of new catalytic reactions for organic synthesis. (soci.org)

Supramolecular catalysis, the use of non-covalent forces to affect a catalytic process, can afford the catalyst diversity required to uncover efficient catalysts and further our understanding. (unl.edu)
An extensive assessment of the catalytic activity, stability and reusability of the catalysts has been conducted in a classical batch reactor. (lancs.ac.uk)

This is accomplished by the carbonylation of alkenes with carboxylic acids. (dntb.gov.ua)
10.1021/ol103128x ) carboxylic acids (not illustrated) from alkenes using CO 2 . (organic-chemistry.org)

When just using one catalytic zone with Zn/SBA-15 as a catalyst, 51.67 wt. (aiche.org)
All reactive intermediates remain bound to the chiral catalyst thereby providing a robust catalytic scheme (no exclusion of air necessary) with excellent stereoinduction. (uni-marburg.de)
Experiments have been carried out to study the effect of reaction temperature, feed molar ratio of alkene to TBHP and catalyst loading on the yield of 1,2-epoxyhexane and 4-vinyl-1-cyclohexane 1,2-epoxide (4-VCH 1,2-epoxide) to optimise the reaction conditions in a batch reactor. (lancs.ac.uk)

Hydrogenation is the addition of molecular hydrogen (H 2 ) to a multiple bond, which converts alkenes to alkanes. (britannica.com)
Catalytic hydrogenation is a useful and relatively common chemical reaction in organic synthesis, usually used to hydrogenate alkenes. (sciencemadness.org)
Furthermore, we proposed a novel approach ( Figure 1 ) of combining two catalytic reforming zones, where the first catalytic reforming zone was intended to improve the cracking of polyolefins into short chain olefins, and the second, lower-temperature catalytic reforming zone was intended for the hydrogenation process to convert these olefins to C5-C12 alkenes. (aiche.org)
In a new study, Argonne chemist Max Delferro boosted and analyzed the unprecedented catalytic activity of an element called vanadium for hydrogenation - a reaction that is used for making everything from vegetable oils to petrochemical products to vitamins. (newswise.com)

Perhaps most surprisingly, the presence of a chiral recognition element positioned remote to the site of catalysis can significantly impact the catalytic activity and enantioselectivity. (unl.edu)

Highly substituted 1,3-dienes produced through catalytic ene-yne metathesis provided substrates for the regioselective hydroboration with variable substituents conveniently introduced from a 1-alkene and a terminal alkyne. (acs.org)
During this work, we investigated the synthesis of these units in enantioenriched form via the Rh(II)-catalyzed cyclopropanation of alkenes using di-acceptor diazo compounds as substrates. (umontreal.ca)

Boron hydrides, compounds of the type R 2 BH, add to alkenes to give organoboranes (hydroboration), which can be oxidized to alcohols with hydrogen peroxide (H 2 O 2 ) (oxidation). (britannica.com)
revealed amide and ester groups direct the gamma-selective Rh-catalyzed hydroboration of 1,1-disubstituted-beta,gamma-unsaturated alkenes. (unl.edu)

The products were further functionalized and were employed in a dual-catalytic cross-coupling reaction. (acs.org)

However, steering the reaction course of photo- and/or electrochemically generated reactive intermediates in a stereocontrolled and catalytic fashion is very challenging. (uni-marburg.de)
[3] On a laboratory scale the Friedel-Crafts reaction uses alkyl halides , as these are often easier to handle than their corresponding alkenes, which tend to be gasses. (wikipedia.org)

AbstractIn this work, a green‐catalytic procedure is used to demonstrate the synthesis of long‐chain anhydrides. (dntb.gov.ua)
The Mizoroki−Heck coupling of aryl halides and alkenes to form C(sp2)-C(sp2) bonds has become a staple transformation in organic synthesis, owing to its broad functional group compatibility and varied scope. (wikipedia.org)
We have expertise in the synthesis and catalytic applications of ligands and metal complexes compatible with proteins, bioconjugation of small molecules to proteins, expression and purification of recombinant enzymes, enzyme engineering and enzyme immobilisation. (nottingham.ac.uk)

Hu, G., Gas chromatographic-mass spectrometric characterization of all acyclic C5-C7 alkenes from fluid catalytic cracked gasoline using polydimethylsiloxane and squalane stationary phases, J. Chromatogr. (chemspider.com)
The largest example of this takes place in the alkylation units of petrochemical plants, which convert low-molecular-weight alkenes into high octane gasoline components. (wikipedia.org)

In part due to the historical difficulties of developing a generally applicable palladium(0)-catalyzed reductive Heck protocol that is compatible with diverse alkenes, various alternative strategies to achieve alkene hydroarylation have been developed. (wikipedia.org)
however, the general mechanism is as follows: the catalytic cycle begins with oxidative addition of a C(sp2)-X (X = Br, Cl, I, OTf, etc.) bond to a palladium(0) complex followed by 1,2-migratory insertion to access an alkylpalladium(II) intermediate (1). (wikipedia.org)
This C(sp3)-PdII intermediate then succumbs to rapid β-hydride elimination to deliver the functionalized alkene product, followed by regeneration of palladium(0) via HX reductive elimination. (wikipedia.org)
I've been working on the replacement of palladium on carbon by powdered catalytic converter. (sciencemadness.org)
While carmakers prefer palladium for catalytic converters, they are turning to platinum, which is cheaper than palladium, to save costs. (jatujakguide.com)

and the structural rearrangement of the reactive Ti-OOR intermediates and solvent to accommodate the alkene. (illinois.edu)

Moreover, comparisons of 1-alkene (C6-C10) epoxidations within Ti-BEA and Ti-SBA-15 show that the turnover rates depend differently on the length of alkene reactants depending on the oxidant identity, which is due to complex interactions among the alkene, the activated oxidant, and the solvent-filled pore of the Ti-silicate. (illinois.edu)

2) A bis-cyclometalated chiral-at-metal rhodium complex (designated as RhO) is demonstrated to catalyze stereocontrolled chemistry of photo-generated radicals and at the same time an enantioselective sulfonyl radical addition to alkenes (Chapter 3.2). (uni-marburg.de)

with 52% of C5-C12 alkanes, 17% of C5-C12 olefins, 14% of C5-C12 aromatics, and 17% of C13+ hydrocarbons from catalytic pyrolysis of polyethylene. (aiche.org)

Here, we show an electrochemical dehydrogenative method in which ammonia is inserted directly into alkenes to build aromatic N -heterocycles in a single step without the use of any external oxidant. (nature.com)
Such an intrinsic obstacle makes the direct insertion of heteroatoms into alkenes to build heterocycles an elusive goal. (nature.com)
Despite these achievements, electricity has not fulfilled the task of sewing NH 3 and alkene to aromatic N -heterocycles. (nature.com)
Fig. 1: Comparison of protocols to construct aromatic N -heterocycles from alkenes. (nature.com)

10.1021/jo200262r ) the more reactive alkene of 3 as the 9-BBN adduct, allowing selective reduction of the less reactive alkene, to give, after reoxidation, the monoreduced 4 . (organic-chemistry.org)

has a high content of aromatic hydrocarbons and a very low content of olefinic hydrocarbons ( alkenes ). (citizendium.org)

In the initial attempt, 1a was adopted as the substrate with the conjugated tetrasubstituted alkene as the target bond to insert a nitrogen atom with ammonia (Table 1 ) at 0 °C. The first observed insertion product 2a had a 16% 1 H NMR yield when graphite felt (GF) was used as the electrodes and methanol was used as the solvent (entry 1). (nature.com)
The halogens bromine and chlorine add to alkenes to yield dihaloalkanes. (britannica.com)

however, in solution the complex is monomeric and catalytically active in the oxidation of alkenes. (rsc.org)
If we can make vanadium or another abundant metal as catalytically active as the noble metals, we can create dramatic cost savings in these very common and commercially important catalytic processes. (newswise.com)

Hydroelementation of terminal alkenes catalyzed by heteroleptic amido-alkaline-earth complexes. (europa.eu)

More recently, protocols have been developed that allow for reductive Heck coupling of unactivated aliphatic and heteroatom-substituted alkenes, which are discussed below. (wikipedia.org)

The latter observation has been posited to arise from a suppression of competing reduction of the C(sp2)-PdII intermediate prior to alkene insertion. (wikipedia.org)

Au cours de cet ouvrage, nous nous sommes intéressés à la synthèse de ces unités sous forme énantioenrichie en utilisant la cyclopropanation d'alcènes par catalyse avec des complexes de Rh(II) utilisant des composés diazoïques di-accepteurs comme substrats. (umontreal.ca)

Use of these complexes for the catalytic immortal ring-opening polymerisation of cyclic monomers derived from renewable bioresources for the production of biocompatible and/or biodegradable polymers. (europa.eu)
Study of the stability and reactivity of the targeted heteroleptic complexes by theoretical calculations: the design of catalytic systems will be elaborated and/or optimized according to preliminary calculations or those based on experimental structural data. (europa.eu)

From their inherent structure, one can view nanotubes as sterically bulky, p-conjugated ligands, or conversely, as electron-deficient alkenes. (sciencewatch.com)

10.1016/j.tetlet.2010.11.036 ) that even the monosubstituted alkene 1 was smoothly converted to the methyl ether 2 by catalytic FeCl 3 . (organic-chemistry.org)
An alkene that is but-1-ene carrying a methyl substituent at position 3. (chemspider.com)

10.1016/j.tetlet.2011.01.065 ) an extraction scheme that allowed the catalytic Os to be re-used repeatedly for the oxidative cleavage. (organic-chemistry.org)

Differentiation of the prochiral faces has been met with few successes from either stoichiometric or catalytic approaches. (unl.edu)

The distinct catalytic activity between these two crystalline surfaces is attributed to the preferential formation of oxide ions and vacancies on c-surfaces. (osti.gov)
When Delferro and his team created the vanadium in this configuration, they saw a dramatic boost in catalytic activity. (newswise.com)

Density functional theory calculations confirmed the close relationship between different catalytic activities in c-surface of oriented and a-surface of unoriented HAP through the tendency of vacancy formation. (osti.gov)

Now, researchers in India have come up with a new catalytic process that could be a game-changer in turning carbon dioxide into our main carbon feedstock. (chemistryworld.com)

The Markovnikov rule expresses the regioselectivity to be expected in the addition of unsymmetrical reagents (such as HX) to unsymmetrical alkenes (such as H 2 C=CHR). (britannica.com)

Organisms2

Chemicals and Drugs19

Analytical, Diagnostic and Therapeutic Techniques and Equipment2

Phenomena and Processes9

Disciplines and Occupations1

Technology, Industry, Agriculture2

Alkynes5

Asymmetric2

Epoxidation9

Reactions12

Catalysts2

Carboxylic acids2

Catalyst3

Hydrogenation4

Enantioselectivity1

Substrates2

Hydroboration2

Dual catalytic1

Reaction2

Synthesis3

Gasoline2

Palladium5

Intermediates1

Epoxidations1

CHEMISTRY1

Pyrolysis1

Heterocycles4

Reactive1

Hydrocarbons1

Yield2

Catalytically2

Terminal1

Reductive1

Insertion1

Catalyse1

Complexes2

Ligands1

Methyl2

Oxidative1

Approaches1

Activity2

Functional1

Process1

Addition1