C1 Feedstock Research Articles

Copper-Catalyzed Tandem Multi-Component Approach to 1,3-Oxazines at Room Temperature by Cross-Dehydrogenative Coupling Using Methanol as C1 Feedstock

A copper(II)-catalyzed multi-component one-pot approach for the synthesis of 1,3-oxazines at room temperature is reported here. Methanol is used as the solvent as well as the carbon source. The methylene carbon of the oxazine product comes from methanol via formaldehyde. tert-Butyl hydroperoxide is used as the oxidant. The reaction uses an environmentally benign metal catalyst and oxidant. No inert atmosphere or precaution is required for the reaction. Most importantly, the reaction avoids the use of carcinogenic formaldehyde.

Unusual Missing Linkers in an Organosulfonate-Based Primitive–Cubic (pcu)-Type Metal–Organic Framework for CO2 Capture and Conversion under Ambient Conditions

A noninterpenetrated organosulfonate-based metal–organic framework (MOF) with a defective primitive–cubic (pcu) topology was successfully synthesized. The unusual missing linkers, along with the highest permanent porosity (∼43%) in sulfonate-MOFs, offer a versatile platform for the incorporation of alkynophilic Ag(I) sites. The cyclic carboxylation of alkyne molecules (e.g., propargyl alcohol and propargyl amine) into α-alkylidene cyclic carbonates and oxazolidinones were successfully catalyzed by the use of Ag(I)-embedded sulfonate-MOF under atmospheric pressure of CO2. In all the three catalytic reactions using CO2 as a C1 feedstock, the highly robust sulfonate-based MOF catalyst exhibit at least three-cycle reusability.

Iridium Clusters Encapsulated in Carbon Nanospheres as Nanocatalysts for Methylation of (Bio)Alcohols.

C-H methylation is an attractive chemical transformation for C-C bonds construction in organic chemistry, yet efficient methylation of readily available (bio)alcohols in water using methanol as sustainable C1 feedstock is limited. Herein, iridium nanocatalysts encapsulated in yolk-shell-structured mesoporous carbon nanospheres (Ir@YSMCNs) were synthesized for this transformation. Monodispersed Ir clusters (ca. 1.0 nm) were encapsulated in situ and spatially isolated within YSMCNs by a silica-assisted sol-gel emulsion strategy. A selection of (bio)alcohols (19 examples) was selectively methylated in aqueous phase with good-to-high yields over the developed Ir@YSMCNs. The improved catalytic efficiencies in terms of activity and selectivity together with the good stability and recyclability were contributable to the ultrasmall Ir clusters with oxidation chemical state as a consequence of the confinement effect of YSMCNs with interconnected nanostructures.

Transition-Metal-Catalyzed Carboxylation of Organic Halides and Their Surrogates with Carbon Dioxide

Carbon dioxide is not only an essential component of ‘greenhouse gases’, but also an abundant, renewable C1 feedstock in organic synthesis. The catalytic incorporation of carbon dioxide into value-added chemicals to produce carboxylic acids has received enormous attention. This review summarizes recent developments in the transition-metal-catalyzed carboxylation of organic halides and their surrogates, such as aryl, vinyl, and alkyl halides and pseudohalides.1 Introduction2 Carboxylation of Aryl Halides and Pseudohalides3 Carboxylation of Vinyl Halides and Pseudohalides4 Carboxylation of Benzyl Halides and Pseudohalides5 Carboxylation of Allyl Halides and Pseudohalides6 Carboxylation of Propargyl Halides and Pseudohalides7 Carboxylation of Alkyl Halides and Pseudohalides8 Direct Carboxylation of C–H Bonds9 Conclusions and Perspectives

Efficient Photoelectrochemical Reduction of Carbon Dioxide to Formic Acid: A Functionalized Ionic Liquid as an Absorbent and Electrolyte.

Photoelectrochemical (PEC) reduction of carbon dioxide (CO2 ) is a potential method for production of fuels and chemicals from a C1 feedstock accumulated in the atmosphere. However, the low solubility of CO2 in water, and complicated processes associated with capture and conversion, render CO2 conversion inefficient. A new concept is proposed in which a PEC system is used to capture and convert CO2 into formic acid. The process is assisted by an ionic liquid (1-aminopropyl-3-methylimidazolium bromide) aqueous solution, which functions as an absorbent and electrolyte at ambient temperature and pressure. Within this PEC reduction strategy, the ionic liquid plays a critical role in promoting the conversion of CO2 to formic acid and suppressing the reduction of H2 O to H2 . At an applied voltage of 1.7 V, the Faradaic efficiency for formic acid production is as high as 94.1 % and the electro-to-chemical efficiency is 86.2 %.

Efficient Photoelectrochemical Reduction of Carbon Dioxide to Formic Acid: A Functionalized Ionic Liquid as an Absorbent and Electrolyte

AbstractPhotoelectrochemical (PEC) reduction of carbon dioxide (CO2) is a potential method for production of fuels and chemicals from a C1 feedstock accumulated in the atmosphere. However, the low solubility of CO2 in water, and complicated processes associated with capture and conversion, render CO2 conversion inefficient. A new concept is proposed in which a PEC system is used to capture and convert CO2 into formic acid. The process is assisted by an ionic liquid (1‐aminopropyl‐3‐methylimidazolium bromide) aqueous solution, which functions as an absorbent and electrolyte at ambient temperature and pressure. Within this PEC reduction strategy, the ionic liquid plays a critical role in promoting the conversion of CO2 to formic acid and suppressing the reduction of H2O to H2. At an applied voltage of 1.7 V, the Faradaic efficiency for formic acid production is as high as 94.1 % and the electro‐to‐chemical efficiency is 86.2 %.

Potassium‐Promoted Molybdenum Carbide as a Highly Active and Selective Catalyst for CO2 Conversion to CO

The high concentration of CO2 bound in seawater represents a significant opportunity to extract and use this CO2 as a C1 feedstock for synthetic fuels. Using an existing process, CO2 and H2 can be concurrently extracted from seawater and then catalytically reacted to produce synthetic fuel. Hydrogenating CO2 directly into liquid hydrocarbons is exceptionally difficult, but by first identifying a catalyst for selective CO production through the reverse water-gas shift (RWGS) reaction, CO can then be hydrogenated to fuel through Fischer-Tropsch (FT) synthesis. Results of this study demonstrate that potassium-promoted molybdenum carbide supported on γ-Al2 O3 (K-Mo2 C/γ-Al2 O3 ) is a low-cost, stable, and highly selective catalyst for RWGS over a wide range of conversions. These findings are supported by X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations.

A Hierarchical Bipyridine-Constructed Framework for Highly Efficient Carbon Dioxide Capture and Catalytic Conversion.

As a C1 feedstock, CO2 has the potential to be uniquely highly economical in both a chemical and a financial sense. Porous materials bearing particular binding and active sites that can capture and convert CO2 simultaneously are promising candidates for CO2 utilization. In this work, a bipyridine-constructed polymer featuring a high surface area, a hierarchical porous structure, and excellent stability was synthesized through free-radical polymerization. After metalation, the resultant catalysts exhibited superior activities in comparison with those of their homogeneous counterparts in the cycloaddition of CO2 to epoxides. The high performance of the heterogeneous catalysts originates from cooperative effects between the CO2 -philic polymer and the embedded metal species. In addition, the catalysts showed excellent stabilities and are readily recyclable; thus, they are promising for practical utilization for the conversion of CO2 into value-added chemicals.

CO2-Mediated Formation of Chiral Carbamates from meso-Epoxides via Polycarbonate Intermediates.

Carbon dioxide has attracted broad interest as a renewable C1 feedstock for efficient transformation into value-added organic chemicals; nevertheless, far less attention was paid to its stereochemically controlled catalytic fixation/conversion processes. Here, we report a new strategy for the selective synthesis of chiral carbamates from carbon dioxide via polycarbonate intermediates, which are formed by the desymmetric copolymerization of meso-epoxides using enantiopure dinuclear Co(III) catalyst systems with 99% enantioselectivity. Subsequent degradation reaction of the resultant polycarbonates with various primary or secondary amine nucleophiles can afford optically active carbamates, with the complete configuration retention of the two chiral carbon centers. Our accomplishment reported here opens up a new route to prepare a wide range of CO2-based carbamate scaffolds with excellent yields and 99% enantiomeric excess.

Thermochemical Reduction of Carbon Dioxide with Alkali Metal Hydrides, Producing Methane and Hydrogen Fuels at Moderate Temperatures

The use of CO2 for the production of fuels has attracted much attention because CO2 can be considered a cheap, nontoxic, and abundant C1 feedstock. In this study, we demonstrated for the first time that CO2 can be effectively reduced by alkali metal hydrides (LiH or NaH) to produce CH4 and H2 fuels concurrently by virtue of heat treatment at moderate temperatures. The yield and mole percent of methane in the gas products for both reaction systems depended upon the reaction temperature and time, and optimal performance was obtained at approximately 450 °C within 48 h. The analysis of the mechanism indicated that amorphous carbon, as an intermediate, plays an important role in the process of CO2-to-CH4 conversion. Alkali metal hydride–CO2 systems are promising reaction systems for the storage and in situ preparation of H2–CH4 mixture fuels.

Effect of supercritical CO2 on the copolymerization behavior of cyclohexene oxide/CO2 and copolymer properties with DMC/Salen‐Co(III) catalyst system

ABSTRACTThe copolymerization of cyclohexene oxide (CHO) and carbon dioxide (CO2) was carried out under supercritical CO2 (scCO2) conditions to afford poly (cyclohexene carbonate) (PCHC) in high yield. The scCO2 provided not only the C1 feedstock but also proved to be a very efficient solvent and processing aid for this copolymerization system. Double metal cyanide (DMC) and salen‐Co(III) catalysts were employed, demonstrating excellent CO2/CHO copolymerization with high yield and high selectivity. Surprisingly, our use of scCO2 was found to significantly enhance the copolymerization efficiency and the quality of the final polymer product. Thermally stable and high molecular weight (MW) copolymers were successfully obtained. Optimization led to excellent catalyst yield (656 wt/wt, polymer/catalyst) and selectivity (over 96% toward polycarbonate) that were significantly beyond what could be achieved in conventional solvents. Moreover, detailed thermal analyses demonstrated that the PCHC copolymer produced in scCO2 exhibited higher glass transition temperatures (Tg ∼ 114 °C) compared to polymer formed in dense phase CO2 (Tg ∼ 77 °C), and hence good thermal stability. Additionally, residual catalyst could be removed from the final polymer using scCO2, pointing toward a green method that avoids the use of conventional volatile organic‐based solvents for both synthesis and work‐up. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2785–2793

Supercritical carbon dioxide design strategies: from drug carriers to soft killers.

The integrated use of supercritical carbon dioxide (scCO(2)) and micro- and nanotechnologies has enabled new sustainable strategies for the manufacturing of new medications. 'Green' scCO(2)-based methodologies are well suited to improve either the synthesis or materials processing leading to the assembly of three-dimensional multifunctional constructs. By using scCO(2) either as C1 feedstock or as solvent, simple, economic, efficient and clean routes can be designed to synthesize materials with unique properties such as polyurea dendrimers and oxazoline-based polymers/oligomers. These new biocompatible, biodegradable and water-soluble polymeric materials can be engineered into multifunctional constructs with antimicrobial activity, targeting moieties, labelling units and/or efficiently loaded with therapeutics. This mini-review highlights the particular features exhibited by these materials resulting directly from the followed supercritical routes.

The Origin of Life--Out of the Blue.

Either to sustain autotrophy, or as a prelude to heterotrophy, organic synthesis from an environmentally available C1 feedstock molecule is crucial to the origin of life. Recent findings augment key literature results and suggest that hydrogen cyanide--"Blausäure"--was that feedstock.

Ionic Liquid-Catalyzed C–S Bond Construction using CO2 as a C1 Building Block under Mild Conditions: A Metal-Free Route to Synthesis of Benzothiazoles

The construction of the C–S bond using CO2 as a C1 feedstock can be considered as a green route for the synthesis of S-containing compounds and is of great significance. Herein, we report the acetate-based ionic liquids (ILs)-catalyzed synthesis of benzothiazoles via cyclization of 2-aminothiophenols with CO2 and hydrosilane under mild conditions (e.g., 60 °C, 0.5 MPa). It was found that the IL (e.g., 1-butyl-3-methylimidazolium acetate, [Bmim][OAc]) served as a multifunctional catalyst with activating CO2 and hydrosilane to form a formoxysilane intermediate, as well as simultaneously activating 2-aminothiophenols through a hydrogen bond, finally resulting in the production of benzothiazoles. [Bmim][OAc] showed the best performance, and a series of benzothiazoles were obtained in high yields. To the best of our knowledge, this is the first protocol for the synthesis of benzothiazoles using CO2 as a C1 building block under metal-free and mild conditions.

Metal–Organic Framework-Based Catalysts: Chemical Fixation of CO2 with Epoxides Leading to Cyclic Organic Carbonates

As a C1 feedstock, CO2 has the potential to be uniquely highly economical in both a chemical and a financial sense. In particular, the highly atom-economical acid-catalyzed cycloaddition of CO2 to epoxides to yield cyclic organic carbonates (OCs), a functionality having many important industrial applications, is an attractive reaction for the utilization of CO2 as a chemical feedstock. Metal–organic frameworks (MOFs) are promising candidates in catalysis as they are a class of crystalline, porous and functional materials with remarkable properties including great surface area, high stability, open channels and permanent porosity. MOFs structure tunability and their affinity for CO2, makes them great catalysts for the formation of OCs using CO2 and epoxides. In this review, we examine MOF-based catalytic materials for the cycloaddition of carbon dioxide to epoxides. Catalysts are grouped based on the location of catalytic sites, i.e., at the struts, nodes, defect sites, or some combination thereof. Additionally, important features of each catalyst system are critically discussed.

Iridium-catalyzed methylation of indoles and pyrroles using methanol as feedstock

A [Cp*IrCl2]2-catalyzed method for the direct methylation of indoles and pyrroles using the abundant and bio-renewable methanol as C1 feedstock.

Polyglycolic acid from the direct polymerization of renewable C1 feedstocks

Potentially sustainable C1 feedstocks carbon monoxide and formaldehyde are subjected to cationic alternating copolymerization to yield polyglycolic acid.

A framework for the analysis of the security of supply of utilising carbon dioxide as a chemical feedstock.

Recent developments in catalysts have enhanced the potential for the utilisation of carbon dioxide as a chemical feedstock. Using the appropriate energy efficient catalyst enables a range of chemical pathways leading to desirable products. In doing so, CO2 provides an economically and environmentally beneficial source of C1 feedstock, while improving the issues relating to security of supply that are associated with fossil-based feedstocks. However, the dependence on catalysts brings other supply chains into consideration, supply chains that may also have security of supply issues. The choice of chemical pathways for specific products will therefore entail an assessment not only of economic factors but also the security of supply issues for the catalysts. This is a multi-criteria decision making problem. In this paper, we present a modified 4A framework based on the framework suggested by the Asian Pacific Energy Research centre for macro-economic applications. The 4A methodology is named after the criteria used to compare alternatives: availability, acceptability, applicability and affordability. We have adapted this framework for the consideration of alternative chemical reaction processes using a micro-economic outlook. Data from a number of sources were collected and used to quantify each of the 4A criteria. A graphical representation of the assessments is used to support the decision maker in comparing alternatives. The framework not only allows for the comparison of processes but also highlights current limitations in the CCU processes. The framework presented can be used by a variety of stakeholders, including regulators, investors, and process industries, with the aim of identifying promising routes within a broader multi-criteria decision making process.

Selective ruthenium-catalyzed methylation of 2-arylethanols using methanol as C1 feedstock.

We describe the selective cross coupling of methanol and 2-arylethanols using a combination of Ru-MACHO (RuHCl(PNP(Ph))CO) and Shvo's diruthenium complex as catalysts. The desired domino transformation takes place via so-called borrowing hydrogen methodology, which constitutes an ideal example of green chemistry.

Ruthenium-Catalyzed Reduction of Carbon Dioxide to Formaldehyde

Functionalization of CO2 is a challenging goal and precedents exist for the generation of HCOOH, CO, CH3OH, and CH4 in mild conditions. In this series, CH2O, a very reactive molecule, remains an elementary C1 building block to be observed. Herein we report the direct observation of free formaldehyde from the borane reduction of CO2 catalyzed by a polyhydride ruthenium complex. Guided by mechanistic studies, we disclose the selective trapping of formaldehyde by in situ condensation with a primary amine into the corresponding imine in very mild conditions. Subsequent hydrolysis into amine and a formalin solution demonstrates for the first time that CO2 can be used as a C1 feedstock to produce formaldehyde.