Styrene Oxide Research Articles

Recyclable N-Heterocyclic Carbene Porous Coordination Polymers with Two Distinct Metal Sites for Transformation of CO2 to Cyclic Carbonates.

Single-component catalysts with integrated multiple reactive centers could work in concert to achieve enhanced activity tailored for specific catalytic reactions, but they remain underdeveloped. Herein, we report the construction of heterogeneous bimetallic porous coordination polymers (PCPs) containing both porphyrin and N-heterocyclic carbene (NHC) metal sites via the coordinative assembly of the NHC functionalities. Three heterobimetallic PCPs (TIPP-Zn-Pd, TIPP-Cu-Pd and TIPP-Ni-Pd) have been prepared to verify this facile synthetic strategy for the first time. In order to establish a cooperative action toward the catalytic CO2 cycloaddition with epoxides, an additional tetraalkylammonium bromide functionality has also been incorporated into these polymeric structures through the N-substituent of the NHC moieties. The resulting heterogeneous bimetallic catalyst TIPP-Zn-Pd exhibits the best catalytic performance in CO2 cycloaddition with styrene oxide (SO) under solvent-free conditions at atmospheric pressure and is applicable to a wide range of epoxides. More importantly, TIPP-Zn-Pd works smoothly and is recyclable in the absence of a cocatalyst under 1.0 MPa of CO2 at 60 °C. This indicates that TIPP-Zn-Pd is quite competitive with the reported heterogeneous catalysts, which typically require a high reaction temperature above 100 °C under cocatalyst-free conditions. Thus, this work provides a new approach to design heterogeneous bimetallic PCP catalysts for high-performance CO2 fixation under mild reaction conditions.

Density-functional tight-binding molecular dynamics study on fixation reaction of CO2 to styrene oxide catalyzed by Mg-MOF-74 metal-organic framework

Abstract Carbon capture and utilization is a strategy to reduce CO2 emissions by utilizing them to synthesize fine chemicals. Mg-MOF-74 exhibits exceptional CO2 adsorption capacity and functions as a catalyst in styrene carbonate synthesis from CO2 and styrene oxide. We examined the structural properties and energetics of styrene carbonate synthesis in Mg-MOF-74 at the third-order density-functional tight-binding level. A novel reaction mechanism via the formation of a seven-membered ring intermediate was found to exhibit a lower Gibbs activation energy than the previously proposed mechanism.

Development of novel heterogeneous cobalt acylpyrazolone catalyst: Synthesis, characterization and selective oxidation of styrene to benzaldehyde

Cobalt acylpyrazolone complex was prepared and characterized using various spectral methods, FT-IR, TGA, UV–visible, DRS, magnetic study, and single crystal XRD. A heterogeneous catalyst consisting of neutral alumina and cobalt complex was synthesized and characterized using various physicochemical methods and successfully applied to styrene oxidation without a solvent. The effects of the reaction variables (mole proportion of the reactantto hydrogen peroxide and TBHP, quantity of the catalyst, reaction period and reaction temperature) were investigated. No appreciable catalytic activity reduction occurred when the catalyst was utilised again. The catalyst's recycling is verified by infrared and diffuse reflectance spectra confirming that the catalyst was intact and notdestroyed following the process. The work's unique feature is its benzaldehyde selectivity under benign reaction circumstances.

A sugar-derived ligand for room temperature aerial oxidation or non-aqueous Markovnikov hydration of styrenes using a preformed or in situ generated Co complex

A novel diaminosugar-salen derived Co(ii) square-planar complex catalyzes the room temperature, aerial oxidation and non-aqueous hydration of styrenes. DFT studies reveal mechanistic details and key ligand features that enable its catalytic ability.

Mesoporous metal-organic framework NH2-MIL-101(Cr) as an efficient photocatalyst for the epoxidation of styrene.

Oxidation of styrene is a key reaction in the synthesis of pharmaceuticals and fine chemicals, and therefore oxidizing styrene with selective, efficient, and recyclable heterogeneous catalysts is significant from an environmental and economic standpoint. In this study, we report the transition Cr-based metal-organic framework [NH2-MIL-101(Cr)] as a heterogeneous photocatalyst, which efficiently promotes styrene epoxidation using H2O2 as a green oxidant, achieving high conversion efficiency (98%) and excellent selectivity (82%) under ambient conditions. Radical detection and quenching experiments reveal that the superoxide radical anion (O2˙-) acts as an active oxygen species, selectively promoting the oxidation of styrene to its oxidized form. This work provides insight into the development of a sustainable and cost-effective method for producing styrene oxide.

Three organic–inorganic polyoxoniobate-based compounds modified with Cu(ii) amine complexes: synthesis, characterization, and catalytic studies for oxidation of styrene

Three novel organic–inorganic polyoxoniobate-based compounds modified with Cu(ii) amine complexes were synthesized under hydrothermal conditions. Additionally, the catalytic efficacy of these compounds in the oxidation of styrene was investigated.

Synthesis of a sulfonamide functionalized poly(styrene oxide) and illustration of a potential post-polymerization strategy

Herein, we demonstrate a design concept for the functionalization of styrene oxide with a sulfonamide protecting group, its respective ring-opening-polymerization, and a related post-polymerization modification.

Regioselective synthesis of 3,4-diarylpyrimido[1,2-b]indazole derivatives enabled by iron-catalyzed ring-opening of styrene oxides.

The first synthesis of 3,4-diarylpyrimido[1,2-b]indazole derivatives from 3-aminoindazoles has been realized. The FeCl3-catalyzed intermolecular epoxide ring-opening reaction altered the order of annulation, with the free primary NH2 groups in 3-aminoindazoles preferentially reacting with styrene oxides instead of aromatic aldehydes. This protocol is further highlighted by its broad substrate compatibility, high chemo- and regioselectivities, and the late-stage modifications of bioactive molecules. Without aromatic aldehydes, the synthesis of 3-aryl-4-acylpyrimido[1,2-b]indazole derivatives can also be accomplished using alternative reaction conditions.

Halide-free CO2 cycloaddition onto styrene oxide catalysed by first row transition-metal derivatives of polyoxotungstates.

Quaternary ammonium salts of metal derivatives of polyoxometalates [XW11O39M(H2O)]n- (X = P, Si; M = Cr, Mn, Co, Ni, Zn) were successfully tested instead of quaternary ammonium halides as catalysts in the cycloaddition of CO2 to styrene oxide. Remarkably, they gave very satisfactory yields of styrene carbonate at moderate temperature (80 °C).

Unraveling the role of internal-external metal substitution in Zn3[Co(CN6)]2 for the styrene oxide-CO2 cycloaddition reaction.

We investigated the influence of the structural and textural properties along with the chemical environment of pure Zn3[Co(CN)6]2 in comparison with the modified phases on the catalytic performance in the cycloaddition reaction between styrene oxide and CO2. We relate these to the proposed reaction pathways and mechanisms. The natural cubic phase (ZnCoCn) was dehydrated to obtain the rhombohedral phase (ZnCoRn), while the stabilized cubic phase (ZnCoCs) was synthesized by substituting external zinc atoms with cadmium atoms. The rhombohedral stabilized phase (ZnCoRs) was achieved by the internal cobalt change with iron. All the materials were extensively characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), and N2 adsorption. The catalytic behavior of the four phases was tested. The crystalline structure of each phase was obtained, and by XPS, it was demonstrated that the chemical environments of all elements conforming to the rhombohedral stabilized phase are different from those of all other materials owing to the exchange of internal metals. The bulk textural properties were similar; only the ZnCoRs presented more micropore area but did not exceed the total surface area of the other materials. The product distribution and yield at reaction times of 2 h and 6 h were closer to those of the cubic phases. The natural rhombohedral phase exhibits the best performance. The tetrabutylammonium bromide (TBAB) and rhombohedral stabilized phase work together to yield a bigger copolymer quantity at the expense of the styrene carbonate (StCO3) production. From the proposed mechanism, the TBAB cation (TBA+) has a "protection" function that drives the closing of the StCO3 ring; however, the charge distribution anisotropy in the four nitrogen atoms generated by Co replacement in ZnCoRs could hold TBA+ as the reaction time progressed, causing an unavailability that triggered the copolymerization propagation step.

Towards metal-free supported quaternary ammonium halide catalysts for an optimized cycloaddition of CO2 onto styrene oxide

Quaternary ammonium salts covalently immobilized on mesoporous silica were found efficient catalysts for CO2 cycloaddition onto styrene oxide under various conditions, including solvent-free conditions and/or in the absence of metal catalysts.

Fe–Cu–chloride ionic liquid immobilized SBA-15 for solvent-free oxidation of styrene to benzaldehyde with H2O2

Copper, iron–chloride ionic liquid (IL) grafted SBA-15 via chloropropylsilane linking demonstrated an effective catalytic performance for the solvent-free oxidation of styrene to benzaldehdye (BzH) with TON 330.5 mol molFe+Cu−1 and 71% selectivity.

Wacker-type oxidation of styrenes with Markovnikov selectivity using copper as a site-selective sequential photooxidant–photoreductant

Copper acts as a site-selective photooxidant and photoreductant, thus enabling the Wacker-type oxidation of styrenes to acetophenones.

A mechanistic study on coupling of CO2 and epoxide mediated by guanidine/TBAI catalysts

Guanidine acted as H-bond donor to activate styrene oxide by (N)H⋯O interaction, facilitating epoxide ring-opening.

Tartaric acid-derived chiral carbon nanodots for catalytic enantioselective ring-opening reactions of styrene oxide.

Chiral carbon nanodots (CNDs) were fabricated through the hydrothermal processing of sulfanilic acid and chiral tartaric acid, exhibiting outstanding catalytic performance for the chiral catalysis of the ring-opening reaction. Furthermore, the catalytic mechanism was proposed to understand the link between the chiral structure and the performance of the catalyst.

Quaternized carbon dots as efficient catalysts for CO2 cycloaddition under solvent- and cocatalyst-free conditions

Novel quaternized carbon dots were synthesized through a microwave method. Br1-CD showed the best catalytic activity and selectivity for CO2 cycloaddition with styrene oxide to 4-phenyl-1,3-dioxolan-2-one under suitable conditions.

Complex isomerism influencing the textural properties of organometallic [Cu(salen)] porous polymers: paramagnetic solid-state NMR characterization and heterogeneous catalysis.

Although organometallic porous polymer networks are recognized as promising heterogeneous catalysts, the relationship between ligand/monomer geometry and network parameters is usually not well understood due to the lack of atom-resolved characterization methods for the amorphous network matrix. In this work, a series of copper(II) salen-type metal complexes was synthesized, using trans- and cis-1,2-diaminocyclohexane segments, and thoroughly characterized by single-crystal X-ray diffraction and solution- and solid-state NMR spectroscopy. Terminal ethynyl groups of the complexes were then transformed into polyacetylene chains by coordination chain-growth homopolymerization, resulting in highly porous (458-655 m2 g-1) organometallic polymer networks with a copper(II) ion content of about 12 wt%. The presence of paramagnetic copper(II) moieties in these complexes and respective polymer networks required the application of tailored NMR techniques, which together with X-ray crystallography and DFT calculations of the paramagnetic NMR shifts made it possible to investigate the differences in the complex geometry in liquid, powder and crystalline form and compare it with the complex geometry in polymer networks. All prepared organometallic polymer networks were also tested as heterogeneous catalysts for styrene oxidation with uncommonly high substrate conversions and compared with their low-molecular-weight analogues. The high reusability of such heterogeneous polymer-based catalysts was also proven.

Efficient photocatalytic CO2 reduction coupled with selective styrene oxidation over a modified g-C3N4/BiOBr composite with high atom economy

A modified g-C3N4/BiOBr composite is developed for photocatalytic CO2 reduction to CO coupled with selective styrene oxidation.

Purified CaO supported Pt nanoparticles for the selective hydrogenation of styrene oxide with enhanced selectivity of 1-phenylethanol

The purified CaO supported Pt nanoparticles exhibit the best selectivity toward 1-phenylethanol in the selective hydrogenation of styrene oxide.

Engineered ionic liquids supported on activated carbon as a sustainable and selective catalyst for viable fixation of CO2 into valuable chemicals

The use of ionic liquids (ILs) based materials in catalysis, especially for CO2 conversion has been attracted great scientific attention due to green catalytic approach and eco-friendliness of the material. In this effort, especially engineered NH2-functionalized imidazolium based ILs with different anions were prepared to develop new covalent ILs functionalized activated carbon (AC) catalysts. All different AC-ILs namely AC-IL-Br, AC-IL-BF4, AC-IL-NTf2 and AC-IL-HSO4 was successfully synthesized by metathesis reaction, and characterized using various analytical and spectroscopic techniques. With the maximum immobilization of the NH2-functionalized ILs on the AC support, the immobilized AC-ILs showed superior structural advantages such as high thermal stability and appreciable surface area. The newly developed AC-ILs as bi-functional catalysts were applied in the fixation of CO2 into epoxide and it displayed high catalytic activity during the catalytic screening. Various reaction variables were surveyed wherein especially, 10.0 wt% of AC-IL-NTf2 catalyst demonstrated the best catalytic activity with 100 % conversion of styrene oxide and 83 % selectivity towards styrene carbonate at 120 °C, 20 bar CO2 pressure in 13 h under solvent-free conditions. The enhanced performance by AC-IL-NTf2 catalyst was achieved as a result of least co-ordination of the NTf2− anion with the NH2-functionalized imidazolium cation which helped in the opening and stabilization of epoxide ring and increased the reaction rate. The best performing AC-IL-NTf2 catalyst was found to be compatible with a broad substrate scope and could effectively produce the respective cyclic carbonates in good to quantitative yields with different substituted epoxides. Most significantly, AC-IL-NTf2 catalyst could be easily separated from the reaction mixture and recycled it for number of cycles. It maintained its catalytic activity without any evident leaching and structural damage up to six recycles. Additionally, plausible reaction mechanism also has been proposed with AC-IL-NTf2 catalyst with the help of catalytic activity results and characterization support.