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Noble metals (Pd, Pt and Rh) incorporated LaFeO3 (LaFe) perovskite oxide nanostructures were synthesized by adapting hydrothermal synthesis method. The synthesized materials were used as catalysts for production of olefins via oxidative cracking of n-propane. The bare LaFe sample exhibited n-propane conversion of 18 % with 42% olefins selectivity at reaction temperature of 600 °C. Substantial increase in n-propane conversion and olefins selectivity was perceived after incorporation of Pd, Pt and Rh in LaFe framework. The LaFe sample incorporated with Rh exhibited superior oxidative cracking performance (85% conversion of n-propane and 79% olefins selectivity) at optimized reaction conditions. A thorough characterization of synthesized catalysts was performed using various characterization techniques to obtain a correlation between the structural properties of Pd, Pt and Rh incorporated LaFe perovskite nanostructures and their catalytic activity in olefin production. The characterization results indicated that Rh and Pt species were expelled from the bulk LaFe framework and dispersed over the surface, while Pd species were strongly interacted with LaFe and occluded inside the LaFe framework. It appears that presence of expelled Rh and Pt species on the LaFe surface are responsible for better redox properties of LaFeRh and LaFePt samples. The highest oxidative catalytic cracking activity of LaFeRh sample is due to presence of high surface area, easily reducible and great number of adsorbed oxygen moieties. Catalyst durability test results indicated that Rh incorporated LaFe sample possessed stable oxidative cracking activity for 72 h without considerable loss in performance

Conversion of methanol to light olefins (MTO) using SAPO-34 molecular-sieve as the reaction catalyst was studied in a fluidized bed reactor within the temperature range of 400–550 °C by 50 °C increments and under 50, 66.6 and 90 vol% of methanol in the feed, diluted with water or an inert. SAPO-34-based catalyst was prepared by agglomeration with clay and alumina to allow proper fluidization. Catalytic results show the highest olefin yield for 500 °C and a reduction in catalyst deactivation for 1:1 methanol:water molar ration in the feed.

Linear alpha-olefins (LAOs) are high-value intermediates for fine chemicals and petrochemicals. The main process for obtaining these products is from olefin oligomerization. The use of heterogenized catalytic systems based on anchoring of organometallic precursors on inorganic materials has the advantages of increasing the selectivity of the reaction and the possibility of reusing the catalyst. In this work, porous clay nanostructures with bi (2D) and three-dimensional (3D) structures were synthesized to act as catalytic supports. A Ni-β-diimine organometallic complex was anchored to these materials giving rise to heterogenized nickel complexes that were tested as catalytic precursors for the ethylene oligomerization reaction, and they were compared with the analogous complex in homogeneous medium. The results showed the influence of the heterogenization of the materials on the thermal stability of the catalyst and the selectivity of the products. Also, the results demonstrated a noticeable influence of the different structures of the materials on catalytic activity. The best result was obtained with the catalyst anchored on the support with a 3D structure, presenting a T.O.F. (turnover frequency) of 754 × 10 ³ h−1. Finally, this material was subjected to recycling tests that qualitatively showed that the catalyst can be reused while maintaining a high selectivity of 95% for alpha-olefins.

Though Olefin-linked covalent organic frameworks (oCOFs) possess excellent π-electron delocalization, the barely reversible olefin linkage brings challenges for oCOFs’ synthesis and functionalization. Here, we synthesize new oCOFs with tertiary amine knots which have twisted configuration and electron-donating nature. Investigation into the structural variation and photoelectric performance shows that the twisted configuration of oCOF-TFPA could favor to the intramolecular charge transfer process and reduce the possibility of aggregation-caused quenching. Photoelectrical measurements and electric band structure calculation both verify the superiority of this oCOFs’ structure in photoelectric sensing.

The examination of cross metathesis reactions leading to the desired product has been conducted to uncover computationally the origin of the chemo-, regio- and stereoselectivity. The comparison between the relative stabilities of all involved intermediates and products, together with the transition states, links to the probability for the respective pathway. Particularly, the respective transition states for each reaction tune the regio- and stereoselectivity because they define the energy barriers needed to be overcome to form the new olefin as final product. The broad range of studied reactions with the 2nd generation Grubbs catalysts allows concluding in detail the points to pay attention and thus helps to understand the chemo-, regio- and stereoselectivity in new olefin metathesis reactions. Here, a web-server joins all these mechanistic insights which is intended to support future predictive olefin metathesis catalysis.

The enantioselective epoxidation of olefin by MnII(R,R-PMCP)(OTf)2, H2O2 and H2SO4 was explored by DFT calculations and experiments. Theoretical results suggest that [MnV(O)(R,R-PMCP)(SO4)]+ species with a triplet ground spin state serves as the active species for the olefin epoxidation. It can be generated by the H2SO4 assisted O-O heterolysis of MnIII(OOH) species. MnIII-persulfate is also involved in this system, but it cannot promote the olefin epoxidation directly, preferring instead to transform into MnV(O). Actually, the asymmetric epoxidation reactions with H2O2/H2SO4 or Oxone provide similar enantioselectivity in the presence of manganese catalyst. These observations further support the transformation of MnIII-persulfate to MnV(O) species.

Development of the economic, environmentally friendly synthesis of amines from nitro compounds remains important and challenging. In this work, the graphene shell encapsulated none noble Ni-based catalysts were successfully designed and synthesized via an environmentally friendly method using H2O or EtOH as solvent. These fresh and recycling catalysts were characterized by X-ray diffraction and X-ray photoelectron spectroscopy. For the nitro compounds hydrogenation, Ni@C-600-H2O exhibits the best catalytic activity to achieve 100 mol% conversions of nitrobenzene and 99% selectivity of aniline under mild reaction conditions of 1.0 MPa H2 and 60 °C. Many halogen-substituted, olefin substituted nitro compounds and aliphatic nitro compounds were investigated and desired products were obtained in excellent selectivity. What is more, the catalyst had excellent stability and could be recycled 13 times without any significant loss in selectivity and activity. Furthermore, we also reported the methodology for tertiary amines synthesis using Ni-based catalyst via one-pot, cost-effective tandem combination reaction with nitrobenzene hydrogenation and amines N-methylation.

A zirconia–titania-based catalyst was synthesized by a co-participation method to study the catalytic cracking of heavy naphtha (dodecane) into high value-added olefins. The nanocrystal-sized catalysts were characterized and the cluster consisted of tetragonal ZrO2 incorporated into anatase TiO2. The catalyst was stable from hydrogen reduction while the surface acidity was increased as more ZrO2 was incorporated into the TiO2 framework. The catalytic cracking of naphtha was increased as the moderate catalytic acidity strength increased and the 50% Zr–Ti oxide catalyst delivered higher conversion between 85–95% with olefin yield around 55–60%. The surface acidity of the Zr–Ti catalyst promoted more cyclization reactions to produce benzene, toluene, and xylene (BTX). The study investigated steam catalytic cracking, which was slightly improved using a lower acidic Zr–Ti catalyst, while the propylene/ethylene ratio was unchanged. The time-on-stream study highlighted the stability of the catalyst with ZrO2 incorporated into the TiO2 framework, to promote olefin yield from naphtha catalytic cracking.

Already 1 mol-% of subvalent [Ga(PhF)2]+[pf]– ([pf]– = [Al(ORF)4]– , RF = C(CF3)3) initiates the hydrosilylation of olefinic double bonds under mild conditions. Reactions with HSiMe3 and HSiEt3 as substrates efficiently yield anti-Markovnikov and anti-addition products, while bulkier substrates like HSiiPr3 are less reactive. Investigating the underlying mechanism by gas chromatography and STEM analysis, we unexpectedly found that H2 and metallic Ga0 formed. Without addition of the olefin, the formation of R3Si–F–Al(ORF)3 (R = alkyl) was observed, a typical degradation product of the [pf]– anion in the presence of a small silylium ion. Electrochemical analysis revealed a surprisingly high oxidation potential of univalent [Ga(PhF)2]+[pf]– in the weakly coordinating, but polar ortho-difluorobenzene of E1/2(Ga+/Ga0; oDFB) = +0.26–0.37 V vs. Fc+ /Fc (depending on the scan rate). Apparently, the subvalent Ga+, mainly known as reductant, initially oxidizes the silane, and generates a highly electrophilic, silane-supported, silylium ion representing the actual catalyst. Consequently, the [Ga(PhF)2]+[pf]– /HSiEt3 system also hydrodefluorinates C(sp3)–F bonds in 1-fluoroadamantane, 1-fluorobutane and PhCF3 at room temperature. In addition, both catalytic reactions may also be initiated by using only 0.2 mol-% of [Ph3C]+[pf]– as silylium ion generating initiator. These results indicate that silylium ion-catalysis is possible with the straight forward accessible weakly coordinating [pf]– anion. Apparently, the kinetics of hydrosilylation and hydrodefluorination are faster than that of anion degradation under ambient conditions. These findings open new windows for main group catalysis.

Structured catalysts have important advantages compared to powder formulations and they are required for processes intensification. In this work, three different ceramic structures: a cordierite monolith, an alumina foam and an alumina-silica paper were used as substrates for the deposition of a NiO-Al2O3 coating and tested in the oxidative dehydrogenation of ethane to produce ethylene. For comparison, a NiO-Al2O3 powder catalyst was also prepared. Nickel oxide species with different physicochemical features were obtained over each structure, evidenced by morphological (SEM-EDX) and physicochemical characterization (XRD, LRS and XPS). The best distributions of the catalytic coatings and NiO physicochemical properties were obtained when the monolith and the foam were used as substrates. These led to higher NiO-Al2O3 interactions and consequently to high ethylene selectivity values, 70–90 %, corresponding to the former an ethane conversion of 22 % and to the latter a 5 %. The distribution of the active phase on the ceramic paper was heterogeneous, with NiO agglomerations and poor NiO-support interaction thus achieving low olefin selectivity (∼ 30 %). The addition of a second element such as cerium was also studied in those structured catalysts with high selectivity, resulting in both cases in an increment of ethane conversion but a decrease in ethylene selectivity. This behavior was attributed to the generation of electrophilic oxygen species.

A modified reaction condition for improved E-selectivity of olefin in Julia-Kocienski reaction of aldehydes having α-coordinating substituents is demonstrated. The chelating groups in aldehyde expected to stabilize syn-transition state (S7) with metal ions, whereas the weakly coordinating quaternary ammonium ion devoid all possible chelating interactions to give E-selective olefins. A systematic investigation is presented to study the size of the protecting group and its chelation effect on E/Z-selectivity in Julia-Kocienski reaction.

The development of efficient and sustainable strategies that evades the utilization of petroleum reserves is highly challenging yet inevitable today. In this regard, the conversion of pine tree-derived β-pinene to highly recognized nopol is particularly attractive owing to its widespread applications. Herein, we describe an approach that enables the selective synthesis of nopol with extraordinarily activity of MIL-101(Cr). This remarkable activity of MIL-101(Cr) attributed to its high specific surface area (SSA), accessible active sites in the mesopore architecture and unsaturated Cr3+ Lewis acid sites. We have established a good correlation between the superior catalytic performance and textural properties of the materials, which can be tuned by using different mineralizing agents. To realize the unprecedented catalytic activity, the influence of reaction parameters, solvent properties, and mineralizing agents have been investigated systematically. The MIL-101(AA) (AA-Acetic acid) exemplified the highest catalytic activity, which is superior to most of the reported materials for this transformation to date. The results of catalyst recycle and hot filtration experiments have emphasized that the catalyst is resistant towards leaching of active sites and retained its original catalytic activity beyond four recycles. An Eley Rideal based model was used to study the reaction kinetics and establish a plausible reaction mechanism. The activation energy of the reaction was found to be 102 kJ mol-1 and the enthalpy of formaldehyde adsorption is -86.88 kJ mol-1.This approach opens up new avenues for the valorization of biomass-based molecules into useful chemicals.

The valorisation of 2,5-dimethylfuran (2,5-dmf) by catalytic fast pyrolysis (CFP) was studied by on-line FTIR-MS gas phase analysis. Zeolite beta, H-ZSM-5 and Cu-ZSM-5 were characterised and used as catalysts. The on-line analysis enables sufficient time resolution to follow subminute transient phenomena, e.g., the impact of catalyst pretreatment and time on stream (TOS) on the reaction selectivity. The results show, that the initial selectivity towards benzene, toluene and xylene (BTX) aromatics is high but decreases with TOS while the isomerisation rates of 2,5-dmf towards 2,4-dimethylfuran and cyclic ketones increase. This indicates the involvement of specific active sites for the different conversion processes. The formation of BTX compounds is linked to the availability of specific olefins, as supported by temperature programmed desorption experiments, which is indicative of aromatisation stemming directly from the olefin pool rather than via Diels–Alder reactions.

The distribution of titanium (Ti) active sites in the framework of TS-1 zeolite is one of the critical factors affecting its catalytic performance, since it can influence accessibility of the Ti active sites and the catalytic utilization of Ti atoms. Here, TS-1 zeolite with homogeneous distribution of titanium atoms in the framework (named BUS-TS-1) is successfully synthesized via bottom-up strategy at high basicity conditions, and BUS-TS-1 zeolite exhibits better catalytic performance for both olefin and alkane oxidation. The comprehensive explorations on the crystallization behavior of BUS-TS-1 zeolite show that, the gripper-like silicon species, as condensed matter in Q2 and Q3 states (detected by 29Si NMR), can be obtained by the condensation of tetraethyl orthosilicate (TEOS) at high alkalinity conditions. The gripper-like silicon species can condense with Ti-OH to form stable and isolated Si-O-Ti species, so that the phase transfer rates of Si and Ti species match during the entire crystallization process, resulting in the homogeneous distribution of Ti atoms. This work offers a useful strategy for the synthesis of high-performance catalysts by regulating the distribution of Ti active-site within TS-1 framework.

Iodonium catalysis is described here to accomplish an intermolecular olefin oxyamination reaction. Urea is used as the O- and N-source to add across both activated and unactivated alkenes in a regioselective manner. Mechanistic studies confirm the presence of an iodonium intermediate.1 Introduction2 Hypothesis3 Optimizations and Scope4 Mechanistic Probes5 Future Outlook

Hydrophilic 2D layered silicate supported Fe3O4 catalyst (Fe3O4/2D-LS) was prepared by an impregnation method and showed greatly improved olefin selectivity in CO hydrogenation. The olefin ratio (O/P) on Fe3O4/2D-LS was increased from 0.50 to 6.05 compared with that of single Fe3O4. Surprisingly, the Fe3O4/2D-LS catalysts had an enhanced chain growth ability and promoted the formation of linear α-olefin in C5+ hydrocarbons increasing from 33.5 to 72.5%. Characterizations showed that layered structure and hydrophilic properties maintained during a CO hydrogenation test. The Fe3O4 supported 2D-LS was easier to reduction and promoted the CO adsorption. The hydroxyl groups on the 2D-LS detected by CA and Zeta may help to increase the selectivity of olefin by inhibiting the secondary reaction of primary olefins.

Cationic amidotitanocene complexes [Cp2 Ti(NPhAr)][B(C6 F5 )4 ] (Cp=η5 -C5 H5 ; Ar=phenyl (1 a), p-tolyl (1 b), p-anisyl (1 c)) were isolated. The bonding situation was studied by DFT (Density Functional Theory) using EDA-NOCV (Energy Decomposition Analysis with Natural Orbitals for Chemical Valence). The polar Ti-N bond in 1 a-c features an unusual inversion of σ and π bond strengths responsible for the balance between stability and reactivity in these coordinatively unsaturated species. In solution, 1 a-c undergo photolytic Ti-N cleavage to release Ti(III) species and aminyl radicals ⋅NPhAr. Reaction of 1 b with H3 BNHMe2 results in fast homolytic Ti-N cleavage to give [Cp2 Ti(H3 BNHMe2 )][B(C6 F5 )4 ] (3). 1 a-c are highly active precatalysts in olefin hydrogenation and silanes/amines cross-dehydrogenative coupling, whilst 3 efficiently catalyzes amine-borane dehydrogenation. The mechanism of olefin hydrogenation was studied by DFT and the cooperative H2 activation key step was disclosed using the Activation Strain Model (ASM).

A Fe embedded MgAl layered double hydroxide (MgAlFe0.4-LDH) showed excellent performances in the epoxidation of various olefins with O2/benzaldehyde as oxidant at mild conditions. Under optimal conditions, the olefins including terminal aliphatic olefins, cyclohexene and styrene were all converted to the corresponding epoxides in conversions close to 100% and selectivity higher than 95%. The epoxidation is accomplished in two elementary steps, which are catalytic oxidation of benzaldehyde to peroxybenzoic acid, and epoxidation of olefin to epoxide by peroxybenzoic acid generated in situ. The catalyst also exhibited good stability and recyclability. The characterization results revealed that the Fe species are present in the state of Fe3+ fully incorporated into the Mg/Al-LDH layers, and act as active sites in the catalyst. The embedment of Fe into MgAl-LDH largely increased the surface area and pore volume of Mg/Al-LDH, which is another factor enhancing the activity of the catalyst.

Fischer–Tropsch has become an indispensable choice in the gas-to-liquid conversion reactions to produce a wide range of petrochemicals using recently emerging biomass or other types of feedstock such as coal or natural gas. Herein we report the incorporation of novel Cu nanoparticles with two Fischer–Tropsch synthesis (FTS) catalytic systems, Fe/reduced graphene oxide (rGO) and Fe–Mn/rGO, to evaluate their FTS performance and olefin productivity in two types of reactors: slurry-bed reactor (SBR) and fixed-bed reactor (FBR). Four catalysts were compared and investigated, namely Fe, FeCu7, FeMn10Cu7, and FeMn16, which were highly dispersed over reduced graphene oxide nanosheets. The catalysts were first characterized by transmission electron microscopy (TEM), nitrogen physisorption, X-ray fluorescence (XRF), X-ray diffraction (XRD), and H-TPR techniques. In the SBR, Cu enhanced olefinity only when used alone in FeCu7 without Mn promotion. When used with Mn, the olefin yield was not changed, but light olefins decreased slightly at the expense of heavier olefins. In the FBR system, Cu as a reduction promoter improved the catalyst activity. It increased the olefin yield mainly due to increased activity, even if the CO2 decreased by the action of Cu promoters. The olefinity of the product was improved by Cu promotion but it did not exceed the landmark made by FeMn16 at 320 °C. The paraffinity was also enhanced by Cu promotion especially in the presence of Mn, indicating a strong synergistic effect. Cu was found to be better than Mn in enhancing the paraffin yield, while Mn is a better olefin yield enhancer. Finally, Cu promotion was found to enhance the selectivity towards light olefins C2–4. This study gives a deep insight into the effect of different highly dispersed FTS catalyst systems on the olefin hydrocarbon productivity and selectivity in two major types of FTS reactors.

An efficient protocol for the synthesis of indole-substituted indanes from o-alkenylbenzaldehydes under acetalization conditions has been presented. The cyclization occurs via a nucleophilic addition of indole on the oxacarbenium ion generated from acetal formed under the reaction condition followed by a conrotatory 4π-electrocyclization reaction, which takes care of the exclusive diastereoselectivity observed during the cyclization step. Olefin geometry of o-alkenylbenzaldehyde and the amount of indole play a decisive role in the success of this cyclization process.

The terpolymerization of a non-polar olefin (such as ethylene) and two different polar functional olefins in a controlled fashion is of great interest and importance but has hardly been explored to date. We report for the first time the terpolymerization of ethylene (E) and two different methoxyaryl-substituted propylenes (AR1 P=hexylanisyl propylene; AR2 P=methoxynaphthyl propylene or methoxypyrenyl propylene) by a half-sandwich scandium catalyst. The terpolymerization took place in a sequence-controlled fashion, affording unique multi-block copolymers composed of two different ethylene-alt-methoxyarylpropylene sequences E-alt-AR1 P (soft segments) and E-alt-AR2 P (hard segments) and relatively short ethylene-ethylene (EE) blocks (crystalline segments). The terpolymers exhibited excellent elasticity and unprecedented self-healing as a result of microphase separation of nanodomains of the crystalline EE segments and the hard amorphous E-alt-AR2 P segments from a very flexible E-alt-AR1 P matrix, demonstrating unique synergy of the three different components.

By using copper(I) homoenolates as nucleophiles, which are generated through the ring-opening of 1-substituted cyclopropane-1-ols, a catalytic asymmetric allylic substitution with allyl phosphates is achieved in high to excellent yields with high enantioselectivity. Both 1-substituted cyclopropane-1-ols and allylic phosphates enjoy broad substrate scopes. Remarkably, various functional groups, such as ether, ester, tosylate, imide, alcohol, nitro, and carbamate are well tolerated. Moreover, the present method is nicely extended to the asymmetric construction of quaternary carbon centers. Some control experiments argue against a radical-based reaction mechanism and a catalytic cycle based on a two-electron process is proposed. Finally, the synthetic utilities of the product are showcased by means of the transformations of the terminal olefin group and the ketone group.

Homogeneous and heterogeneous catalyzed reactions can seldom operate synergistically under the same conditions. Here we communicate the use of a single rhodium precursor that acts in both the homogeneous and heterogeneous phases for the asymmetric full saturation of vinylarenes that, to date, constitute an unmet bottleneck in the field. A simple asymmetric hydrogenation of a styrenic olefin, enabled by a ligand accelerated effect, accounted for the facial selectivity in the consecutive arene hydrogenation. Tuning the ratio between the phosphine ligand and the rhodium precursor controlled the formation of homogeneous and heterogeneous catalytic species that operate without interference from each other. The system is flexible in terms of both the chiral ligand and the nature of the external olefin. We anticipate that our findings will promote the development of asymmetric arene hydrogenations.

A catalytic reactive distillation reactor, previously described, was improved to increase the production of middle and heavy hydrocarbons, to be used as feedstock or fuel in the viewpoint of a Circular Economy of plastics. The thermal and catalytic pyrolysis experiments were run using high density polyethylene (HDPE) under several experimental conditions, with a 1 % (w/w) of HZSM-5 for catalytic pyrolysis. Three different temperatures were tested in each case and the influence of the reaction time was evaluated at 500 °C and 430 °C for thermal pyrolysis and catalytic pyrolysis, respectively. Thermal pyrolysis of HDPE produced the higher amount of solid products (80 %wt. or higher) under the form of a waxy cream-colored material (wax) for all the experimental sets. For catalytic pyrolysis, the major product fraction was always liquid. The analysis of the liquid products showed that, for both thermal and catalytic pyrolysis, the products obtained were within the range of C5 to C11, with a higher yield on C8 and C9 in the case of thermal pyrolysis and on C6 and C7 for catalytic pyrolysis. The aim of this study was the development of an integrated reactor/separation system to increase the middle olefin production. It is possible with this reactor design to direct the pyrolysis of HDPE to the production of middle olefins that can be reused in the petrochemistry industry, as chemical feedstock, including in the production of new plastics.

The nitrogen oxides NO2, NO, and N2O are among the most potent air pollutants of the 21st century. A bimetallic RhI–PtII complex containing an especially designed multidentate phosphine olefin ligand is capable of catalytically detoxifying these nitrogen oxides in the presence of hydrogen to form water and dinitrogen as benign products. The catalytic reactions were performed at room temperature and low pressures (3–4 bar for combined nitrogen oxides and hydrogen gases). A turnover number (TON) of 587 for the reduction of nitrous oxide (N2O) to water and N2 was recorded, making these RhI–PtII complexes the best homogeneous catalysts for this reaction to date. Lower TONs were achieved in the conversion of nitric oxide (NO, TON=38) or nitrogen dioxide (NO2, TON of 8). These unprecedented homogeneously catalyzed hydrogenation reactions of NOx were investigated by a combination of multinuclear NMR techniques and DFT calculations, which provide insight into a possible reaction mechanism. The hydrogenation of NO2 proceeds stepwise, to first give NO and H2O, followed by the generation of N2O and H2O, which is then further converted to N2 and H2O. The nitrogen−nitrogen bond-forming step takes place in the conversion from NO to N2O and involves reductive dimerization of NO at a rhodium center to give a hyponitrite (N2O22−) complex, which was detected as an intermediate., Angewandte Chemie. International Edition, 60 (48), ISSN:1433-7851, ISSN:1521-3773, ISSN:0570-0833

Chiral phosphoramidite–olefin hybrid ligands were found to be effective in the iridium-catalyzed asymmetric alkylation of N-arylbenzamides with vinyl ethers. The reaction is catalyzed by a hydroxo­iridium catalyst coordinated with the hybrid ligand to give the corresponding products in high yields with high branch selectivity and enantioselectivity.

Substituted Olefin-based compounds are attractive targets in the design of novel chemical structures for the discovery of new drugs. In the current study, we have synthesized a series of new tri-su...

We report herein an intermolecular syn-arylalkylation and alkenylalkylation of alkenyl amines with two different organohalides (iodides and bromides) using Ni(II) catalyst. The cleavable bidentate quinolinamide is utilized after extensive directing group screening to enable olefin difunctionalization with high levels of regio-, chemo-, and diastereocontrol. This general and practical protocol is compatible with α- or β-substituted terminal alkenes and internal alkenes, providing rapid access to branched aliphatic amines bearing two skipped and vicinal stereocenters with high diastereoselectivities that would otherwise be difficult to synthesize.

The prezizane‐type sesquiterpene agarozizanol B was synthesized employing a photochemical cascade reaction as the key step. Starting from a readily available 1‐indanone with a tethered olefin, a strained tetracyclic skeleton was assembled which contained all carbon atoms of the sesquiterpene with the correct relative configuration. The conversion into the tricyclic prezizane skeleton was accomplished by a strategic cyclopropane bond cleavage. Prior to the cyclopropane ring opening an adaption of the oxidation state was required, which could be combined with a reductive resolution step. After removal of two functional groups, the natural product was obtained both in racemic form or, if resolved, as the (+)‐enantiomer which was shown to be identical to the natural product., Starting from a simple indanone derivative, diastereomerically pure intermediate 1 was formed in a photochemical cascade and served as precursor to agarozizanol B (2), either as racemate or as single enantiomer after a resolution step.

The utilization of carbon dioxide as a polymer feedstock is an ongoing challenge. This report describes the catalytic conversion of carbon dioxide and an olefin comonomer, 1,3-butadiene, into a polymer structure that arises from divergent propagation mechanisms. Disubstituted unsaturated δ-valerolactone

The natural schweinfurthins are stilbenes with significant antiproliferative activity and an uncertain mechanism of action. To obtain a fluorescent analogue with minimal deviation from the natural structure, a coumarin ring system was annulated to the D-ring, creating a new analogue of schweinfurthin F. This stilbene was prepared through a convergent synthesis, with a Horner-Wadsworth-Emmons condensation employed to form the central stilbene olefin. After preparation of a tricyclic phosphonate via a recent and more efficient modification of the classic Arbuzov reaction, condensation was attempted with an appropriately substituted bicyclic aldehyde but the coumarin system did not survive the reaction conditions. When olefin formation preceded generation of the coumarin, the stilbene formation proceeded smoothly and ultimately allowed access to the targeted coumarin-based schweinfurthin analogue. This analogue displayed the desired fluorescence properties along with significant biological activity in the National Cancer Institute's 60-cell line bioassay, and the pattern of this biological activity mirrored that of the natural product schweinfurthin F. This approach gives facile access to new fluorescent analogues of the natural schweinfurthins and should be applicable to other natural stilbenes as well.

Palladium-catalyzed alkene functionalization was discovered more than 60 years ago and is now a commonly used strategy for the synthesis of pharmaceuticals and materials. The development of asymmetric variants of this reaction is described in this short review. The review is organized around the mechanistic challenges that have hampered the development of these transformations for various substrate classes, as well as the strategies, ligand classes, and additives that have been introduced to overcome them. New methodologies for Heck, oxidative Heck, dehydrogenative Heck, and Wacker-type reactions are highlighted, with a special focus on the progression from cyclic to acyclic to electronically unbiased olefin substrates.

The rate constants and kinetic coefficients of inhibition (fkin) for olefins oxidized with the transition metal compounds (Mn) were measured by highly sensitive microvolumometry at 323 K in combination with kinetic modeling. The cyclic mechanism of the reactions of hydroxyl radicals with Mn leading to the multiple chain termination was confirmed as indicated by the observed effect of long-term inhibition of the oxidation of the substrates with Mn and obtained values of fkin > 102.

WO3–x (W-1) was used to achieve controllable photoisomerization of linear olefins without substituents under 625 nm light irradiation. Thermodynamic and kinetic isomers were obtained by regulating the carbon chain length of the olefins. Terminal olefins were converted into isomerized products, and the internal olefin mixtures present in petroleum derivatives were transformed into valuable pure olefin products. Oxygen vacancies (OVs) in W-1 altered the electronic structure of W-1 to improve its light-harvesting ability, which accounted for the high activity of olefin isomerization under light irradiation up to 625 nm. Additionally, OVs on the W-1 surface generated unsaturated W5+ sites that coordinated with olefins for the efficient adsorption and activation of olefins. Mechanistic studies reveal that the in situ formation of surface π-complexes and π-allylic W intermediates originating from the coordination of coordinated unsaturated W5+ sites and olefins ensure high photocatalytic activity and selectivity of W-1 for the photocatalytic isomerization of olefins via a radical mechanism.

The discovery of the high activity and selectivity of boron-based catalysts for oxidative dehydrogenation (ODH) of alkanes to olefins has attracted significant attention in the exploration of a new method for the synthesis of highly active and selective catalysts. Herein, we describe the synthesis of porous boron-doped silica nanofibers (PBSNs) 100–150 nm in diameter by electrospinning and the study of their catalytic performance. The electrospinning synthesis of the catalyst ensures the uniform dispersion and stability of the boron species on the open silica fiber framework. The one-dimensional nanofibers with open pore structures not only prevented diffusion limitation but also guaranteed high catalytic activity at high weight hourly space velocity (WHSV) in the ODH of alkanes. Compared to other supported boron oxide catalysts, PBSN catalysts showed higher olefin selectivity and stability. The presence of Si−OH groups in silica-supported boron catalysts may cause low propylene selectivity during the ODH of propane. When the ODH conversion of ethane reached 44.3%, the selectivity and productivity of ethylene were 84% and 44.2% gcat−1 s−1, respectively. In the case of propane ODH, the conversion, selectivity of olefins, and productivity of propylene are 19.2%, 90%, and 76.6 μmol gcat−1 s−1, respectively. No significant variations in the conversion and product selectivity occurred during 20 h of operation at a high WHSV of 84.6 h−1. Transient analysis and kinetic experiments indicated that the activation of O2 was influenced by alkanes during the ODH reaction.

A series of mono- and polynuclear bis(phenoxy-imine) titanium and zirconium complexes were synthesized. The complexes were immobilized on an MgCl2 carrier prepared by different methods. The homogeneous complexes and supported catalysts were evaluated for ethylene polymerization. The effects of the nuclearity of the precatalysts, nature of organoaluminum activator and the polymerization temperature were examined. It has been shown that immobilized on MgCl2 catalysts are superior in activity to homogeneous precatalysts by the level of activity (up to 6.1 ton of PE (molM h atm)−1). The precatalysts obtained in situ by the interaction of FI complexes, Bu2Mg and Et2AlCl are suitable for preparing ultra-high molecular weight polyethylene (UHMWPE) with molecular weight up to 6 106 Da even at elevated reaction temperatures. In addition, supported precatalysts, in the presence of MAO, effectively catalyze the ethylene–higher olefin copolymerization (activity—up to 8.2 ton of copolymer (molM⋅h⋅atm)−1).

Silver(I) ions undergo selective olefin complexation and have been utilized in various olefin/paraffin separation techniques such as argentation chromatography and facilitated transport membranes. Ionic liquids (ILs) are solvents known for their low vapor pressure, high thermal stability, low melting points, and ability to promote a favorable solvation environment for silver(I) ion-olefin interactions. To develop highly selective separation systems, a fundamental understanding of analyte partitioning to the stationary phase and the thermodynamic driving forces behind solvation is required. In this study, a chromatographic model treating silver(I) ions as a pseudophase is constructed and employed for the first time to investigate the olefin separation mechanism in silver(I) salt/IL mixtures. Stationary phases containing varying amounts of noncoordinated silver(I) salt ([Ag+][NTf2-]) dissolved in the 1-decyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C10MIM+][NTf2-]) IL are utilized to determine the partition coefficients of various analytes including alkanes, alkenes, alkynes, aromatics, aldehyde, esters, and ketones. As ligand coordination to silver(I) ions is known to lower its olefin complexation capability, this study also examines two different types of coordinated silver(I) ion pseudophases, namely, monocoordinated silver(I) salt ([Ag+(1-decyl-2-methylimidazole, DMIM)][NTf2-]) and dicoordinated silver(I) salt ([Ag+(1-methylimidazole, MIM)(DMIM)][NTf2-]). The extent of olefin partitioning to the coordinated silver(I) ion pseudophases over the carrier gas and IL decreased by up to two orders of magnitude. Values for enthalpy, entropy, and free energy of solvation were determined for the three silver(I) ion-containing systems. Olefin retention was observed to be enthalpically dominated, while ligand coordination to the silver(I) ion pseudophase resulted in variations for both enthalpic and entropic contributions to the free energy of solvation. The developed model can be used to study chemical changes that occur in silver(I) ions over time as well as identify optimal silver(I) salt/IL mixtures that yield high olefin selectivity.

Asymmetric hydrogenation of olefins is one of the most powerful asymmetric transformations in molecular synthesis. Although several privileged catalyst scaffolds are available, the catalyst development for asymmetric hydrogenation is still a time- and resource-consuming process due to the lack of predictive catalyst design strategy. Targeting the data-driven design of asymmetric catalysis, we herein report the development of a standardized database that contains the detailed information of over 12000 literature asymmetric hydrogenations of olefins. This database provides a valuable platform for the machine learning applications in asymmetric catalysis. Based on this database, we developed a hierarchical learning approach to achieve predictive machine leaning model using only dozens of enantioselectivity data with the target olefin, which offers a useful solution for the few-shot learning problem and will facilitate the reaction optimization with new olefin substrate in catalysis screening.

A lumped kinetic model has been developed for the methanol to olefins (MTO) reaction over phosphorus modified HZSM-5 catalyst. In consideration of mixed feed cracking, a higher reaction temperature than the conventional MTO reaction was chosen. The reaction temperature considered is in range of 500 to 680 °C. The experimental data for the kinetic model were obtained in an isothermal fixed bed reactor over a wide range of operating temperatures and space time of 0.160 to 0.801 g-cat·h/mole of methanol feed. A reaction mechanism comprising seven lumps was utilized to analyze the kinetic behavior of this catalyst. Based on the mathematical kinetic model for the fixed bed reactor, the kinetic parameters were determined by numerical optimization using a hybrid of genetic algorithm and active set gradient method. The developed kinetic model reasonably predicts the experimental data obtained for the reaction conditions considered. It has been found that increasing space time is favorable to light olefins yield, while a maximum water free basis olefin yield of about 82 weight % was obtained at a temperature of 630 °C for a space time of 0.801 g-cat·h/mole of methanol feed.

Efficient olefin aziridination has been achieved with a tris(triazolyl)methane copper catalyst supported onto polystyrene. Aryl, alkyl and methoxycarbonyl-substituted olefins are converted into N-tosylaziridines in good to high yields. The solid catalyst is readily separated by filtration and recycled, allowing its reuse with no significant loss of the catalytic activity.