Atmospheric CO2 Pressure Research Articles

Ni-Catalyzed Direct Carboxylation of an Unactivated C-H Bond with CO2.

The transition-metal-catalyzed direct carboxylation of an unactivated C-H bond is rarely reported, and no example of catalysis using abundant and cheap nickel has been reported. In this work, the first Ni-catalyzed direct carboxylation of an unactivated C-H bond under an atmospheric pressure of CO2 is reported. This method affords moderate to high carboxylation yields of various methyl carboxylates under mild conditions. Preliminary mechanistic studies reveal that a Ni(0)-Ni(II)-Ni(I) catalytic cycle may be involved in this reaction.

Application of Ag/TFPG-DMB COF in carbamates synthesis via CO2 fixation reaction and one-pot reductive N-formylation of nitroarenes under sunlight

We have designed mesoporous AgNPs decorated COF (Ag/TFPG-DMB COF) nanomaterial which has been formed by an easy ex-situ synthetic method. The synthesized material is characterized by FTIR, PXRD, UV–vis, N2 adsorption–desorption studies, TEM, FESEM and XPS. The material showed the generation of identical mesopore at 3.9 nm. It is observed that the material can perform as both thermally and photochemically active catalyst for carbamate synthesis and one-pot reduction and N-formylation of nitroarenes respectively. The catalytic activity of the Ag/ TFPG-DMB COF nanomaterial is checked for green synthesis of carbamates from different amines and alcohols under 1 atmospheric pressure of CO2 with excellent yield (upto 95 %) as well as with high TOF value (182 h−1) and high selectivity. Additionally, the Ag/ TFPG-DMB COF nanomaterial is also applied as a potentially active photocatalyst for one-pot nitroarene reduction along with N-formylation reaction under sunlight irradiation in green reaction conditions with exceptionally high yield of formylated products upto 99 % as well as with high TOF value (762 h −1). The catalyst efficiently reduced and formylated para-nitrophenol, a potential water pollutant, which elaborates its scope as an efficient catalyst for water purification also. The catalyst recyclability is also checked for five reaction cycles for both the reactions and the Ag/TFPG-DMB COF material showed outstanding recycling ability without any noticeable leaching of active metal or catalyst degradation.

Efficient synthesis of 2-amino-3-methylenephthalimides by a palladium-catalyzed intramolecular aminocarbonylation

An efficient synthesis of 2-amino-3-methylenephthalimide through palladium-catalyzed intramolecular aminocarbonylation has been developed. The reaction carried out under atmospheric pressure of CO and provided diversified 2-amino-3-methylenephthalimides in reasonable to good yields from o-iodoacetophenone phenylhydrazone, which are readily derived from phenylhydrazines and 2-iodoacetophenones.

MIL-101(Cr) for CO2 Conversion into Cyclic Carbonates, Under Solvent and Co-Catalyst Free Mild Reaction Conditions

Mild reaction conditions (nearly room temperature and atmospheric CO2 pressure) for the cycloaddition of CO2 with epoxides to produce cyclic carbonates were investigated applying MIL-101(Cr) as a catalyst. The MIL-101 catalyst contains strong acid sites, which promote the ring-opening of the epoxide substrate. Moreover, the high surface area, enabling the adsorption of more CO2 (substrate), combined with a large pore size of the catalyst is essential for the catalytic performance. Additionally, epoxide substrates bearing electron-withdrawing substituents or having a low boiling point demonstrated an excellent conversion towards the cyclic carbonates. MIL-101(Cr) for the cycloaddition of carbon dioxide with epoxides is demonstrated to be a robust and stable catalyst able to be re-used at least five times without loss in activity.

Partners in catalysis.

A heterodinuclear MgCo catalyst has been shown to be highly active for the copolymerization of CO2 and epoxides under low (atmospheric) CO2 pressures. Its performance arises from the intramolecular synergy between the two metals, which adopt distinct roles and mediate each other’s reactivity during catalysis.

Exploring the potential of group III salen complexes for the conversion of CO2 under ambient conditions

Monometallic and bimetallic scandium and yttrium-salen complexes were synthesized and applied for the first time as homogeneous Lewis acids for the cycloaddition of CO2 to epoxides in the presence of quaternary ammonium salts. The developed rare-earth-based complexes showed the ability to catalyze the coupling of CO2 and industrially attractive epoxides such as epichlorohydrin and propylene oxide into cyclic carbonates under ambient conditions using low metal loading and leading to turnover numbers (TON) over 100. Additionally, functionalized cyclic carbonates with potential for application in polymer synthesis were obtained under mild conditions (T = 40−60 °C) under atmospheric CO2 pressure. DFT calculations were carried out to gain insight into the reaction mechanism justifying the observed difference of activity between the different complexes and indicating milder reaction barriers for the yttrium and scandium-based salen species compared to a homologous chromium complex. Moreover, advanced buried volume calculations were performed to assess the accessibility of the catalytic pockets in monometallic salen complexes versus bimetallic salen complexes.

Facile, High‐Yielding Synthesis of 4‐Functionalised 1,2,3‐Triazoles via Amino‐ and Aryloxycarbonylation

Abstract4‐Iodo‐1,2,3‐triazoles were synthesised via azide‐alkyne cycloaddition of alkynyl Grignard reagent and benzyl azide followed by iodination reaction. The aminocarbonylation and aryloxycarbonylation of 4‐iodo‐1,2,3‐triazoles were carried out in the presence of various N‐ and O‐nucleophiles, resulting in the corresponding triazole‐based 4‐carboxamides and 4‐esters, respectively. Both high‐yielding reactions were carried out under mild conditions (atmospheric CO pressure, 70 °C).

Rh(i)-Catalyzed regioselective arylcarboxylation of acrylamides with arylboronic acids and CO2

The first Rh(i)-catalyzed regioselective arylcarboxylation of electron-deficient acrylamides with arylboronic acids under atmospheric pressure of CO2 has been developed.

A probabilistic case for a large missing carbon sink on Mars after 3.5 billion years ago

Mars has a thin (6 mbar) CO2 atmosphere currently. There is strong evidence for paleolakes and rivers formed by warm climates on Mars, including after 3.5 billion years (Ga) ago, which indicates that a CO2 atmosphere thick enough to permit a warm climate was present at these times. Since Mars no longer has a thick CO2 atmosphere, it must have been lost. One possibility is that Martian CO2 was lost to space. Oxygen escape rates from Mars are high enough to account for loss of a thick CO2 atmosphere, if CO2 was the main source of escaping O. But here, using H isotope ratios, O escape calculations, and quantification of the surface O sinks on Mars, we show for the first time that O escape from Mars after 3.5 Ga must have been predominantly associated with the loss of H2O, not CO2, and therefore it is unlikely that ≥250 mbar Martian CO2 has been lost to space in the last 3.5 Ga, because such results require highly unfavored O loss scenarios. It is possible that the presence of young rivers and lakes on Mars could be reconciled with limited CO2 loss to space if crater chronologies on Mars are sufficiently incorrect that all apparently young rivers and lakes are actually older than 3.5 Ga, or if climate solutions exist for sustained runoff on Mars with atmospheric CO2 pressure <250 mbar. However, our preferred solution to reconcile the presence of <3.5 Gya rivers and lakes on Mars with the limited potential for CO2 loss to space is a large, as yet undiscovered, geological C sink on Mars.

Efficient and Recyclable Cobalt(II)/Ionic Liquid Catalytic System for CO2 Conversion to Prepare 2‐Oxazolinones at Atmospheric Pressure

Summary of main observation and conclusionConverting CO2 into value‐added chemicals represents a promising way to alleviate the CO2 derived environmental issues, for which the development of catalysts with high efficiency and recyclability is very desirable. Herein, the catalytic system by combining cobalt source and ionic liquid (IL) has been developed as the efficacious and recyclable catalyst for the carboxylative cyclization of propargylic amine and CO2 to prepare 2‐oxazolinones. In this protocol, various propargylic amines were successfully transformed into the corresponding 2‐oxazolinones with CoBr2 and diethylimidazolium acetate ([EEIM][OAc]) as the catalyst under atmospheric CO2 pressure. It is worth noting that the turnover number (TON) of this transformation can be up to 1740, presumably being attributed to the cooperative effect of the cobalt and IL. Furthermore, the existence of IL enables the catalytic system to be easily recycled to 10 times without losing its activity.

Diversity-Oriented Metal Decoration on UiO-Type Metal-Organic Frameworks: an Efficient Approach to Increase CO2 Uptake and Catalytic Conversion to Cyclic Carbonates.

A library of metallo-bipyridine UiO-type metal–organic frameworks (MOFs) has been successfully synthesized by postmetallation of a wide range of metal complexes into bidentate bipyridine moieties. Then, a systematic investigation is devoted to a catalytic evaluation of the resultant MOFs containing a binary Lewis acid function for the synthesis of cyclic carbonates from epoxides and carbon dioxide (CO2). The result indicated that the metal-grafted MOFs exhibit improvement in terms of CO2 uptake capacity and catalytic activity in comparison with their nonmetallated counterparts. The comprehensive investigation provides a valuable insight into the synergetic effects of MOF functionalities including metal node, grafted metal, and its counterion in the cycloaddition reaction. Furthermore, the metal coordination modulation due to its benefits such as being a solvent-free process, nearly full conversion to cyclic carbonates, high selectivity and high CO2 uptake, applying atmospheric CO2 pressure, and excellent stability and easy recyclability of the catalyst demonstrates them as promising candidates for practical utilization of CO2 conversion into value-added chemicals.

The Fabrication of Rigid Crosslinker-Decorated Gold Nanoparticle Array Film for Catalyzing CO2 Cycloaddition

Abstract In order to precisely design the active sites in two-dimensional (2D) gold-based catalysts, we have developed a convenient and versatile plasma-assisted droplet evaporation-rigid crosslinking method for the fabrication of gold nanoparticle (Au NP) array film. Four kinds of Au NP arrays have been decorated respectively with rigid sulfurated crosslinkers i.e. thieno[3,2-b]thiophene, 2,2′-bithiophene, 1,4-benzenedithiol and 4,4′-thiodibenzenethiol, and the density of crosslinkers can be adjusted under plasma treatment. Particularly, the utilization of 4,4′-thiodibenzenethiol gave uniform particle sizes to form a periodical 2D structure, which provides multiple exposed active sites of gold nanoparticles rather than enwinding by the alkyl chains. Meanwhile, the weaker electron-donating effect and steric hindrance of rigid groups in the crosslinkers could also enhance the catalytic activity. In addition, the Au NP array film can be transferred from the glass substrate and further composited with polymers and metal organic framework (MOF) into self-standing composite membrane. Therefore, this rigid crosslinked array film can serve as an environmentally friendly catalyst for CO2 cycloaddition under atmospheric CO2 pressure, which offers a novel application of Au NPs array film, and opens up a new way for the design and fabrication of 2D hybrid materials.

Catalytic CO2 Fixation over a Robust Lactam-Functionalized Cu(II) Metal Organic Framework

A porous, Cu(II)-metal organic framework (Cu-MOF) constituted of a rigid lactam functionalized ditopic ligand (H2L) was synthesized at room temperature under slow evaporation conditions {H2L = (5-(1-oxo-2,3-dihydro-1H-inden-2-yl)isophthalic acid)}. The single crystal X-ray structure revealed the formation of a 3D framework of Cu-MOF with one-dimensional (1D) channels decorated with lactam groups and exposed metal centers in the crystallographic c-axis. Interestingly, Cu(II) coordinated DMF molecules were eliminated from the Cu(II) metal center on activation of Cu-MOF at a temperature of 150 °C under high vacuum to generate a solvent free framework with pores lined with unsaturated Lewis acidic Cu(II) ions, i.e., Cu-MOF'. The lactam functionalized channels inclined toward the CO2, which interact with the Cu(II) metal sites lined in the channels of Cu-MOF' and exhibit fascinating solvent-free heterogeneous catalytic conversion of CO2 to cyclic carbonates at atmospheric pressure of CO2, under mild conditions. Furthermore, the Cu-MOF' catalyst was easily recycled and reused for several cycles without a significant loss in catalytic activity.

Functionalisation of the uracil ring via palladium-catalysed aminocarbonylation

Iodouracil derivatives (5-iodouracil, 5-iodo-1,3-dimethyluracil) were aminocarbonylated using a set of primary and secondary amines in the presence of in situ palladium(0) catalysts. The formation of carboxamides via single CO insertion was favoured at atmospheric CO pressure. The chemoselectivity toward double CO insertion can be increased by using 40 bar of CO pressure, in this way up to 60% selectivity toward 2-ketocarboxamide was achieved. In the case of 5-iodouracil the corresponding 5-glyoxylamido-uracil derivatives were exclusively formed at 40 bar CO pressure. The only exception is the less basic aniline nucleophile which provided the corresponding carboxamide exclusively. A typical side-reaction took place when 5-iodouracil was used as substrate: this heterocycle, existing in lactam-lactim tautomeric forms, underwent deiodination providing the parent uracil as side-product.

Copper-Catalyzed Carboxylation of C–F Bonds with CO2

An effective Cu-catalyzed selective formal carboxylation of C–F bonds with an atmospheric pressure of CO2 is reported. A variety of gem-difluoroalkenes, gem-difluorodienes, and α-trifluoro-methyl a...

Palladium-catalyzed carbonylative synthesis of indoloisoindoloquinazolinone derivatives by using CO as a carbonyl source

An efficient synthesis of indolo[1,2-c]isoindolo[2,1-a]quinazolin-5(16aH)-one derivatives through palladium-catalyzed cyclocarbonylation reaction of 6-(2-bromoaryl)-5,6-dihydroindolo[1,2-c]quinazolines with the use of CO as a carbonyl source under atmospheric pressure has been disclosed. More intriguingly, the above-mentioned products can also be obtained directly from a one-pot two-step tandem reaction of 2-(1H-indol-2-yl)anilines and 2-bromobenzaldehydes, which are the precursors of 6-(2-bromoaryl)-5,6-dihydroindolo[1,2-c]quinazolines, under an atmospheric CO pressure in modest yields.

Deep Atlantic Ocean carbon storage and the rise of 100,000-year glacial cycles

Over the past three million years, Earth’s climate oscillated between warmer interglacials with reduced terrestrial ice volume and cooler glacials with expanded polar ice sheets. These climate cycles, as reflected in benthic foraminiferal oxygen isotopes, transitioned from dominantly 41-kyr to 100-kyr periodicities during the mid-Pleistocene 1,250 to 700 kyr ago (ka). Because orbital forcing did not shift at this time, the ultimate cause of this mid-Pleistocene transition remains enigmatic. Here we present foraminiferal trace element (B/Ca, Cd/Ca) and Nd isotope data that demonstrate a close linkage between Atlantic Ocean meridional overturning circulation and deep ocean carbon storage across the mid-Pleistocene transition. Specifically, between 950 and 900 ka, carbonate ion saturation decreased by 30 µmol kg−1 and phosphate concentration increased by 0.5 µmol kg−1 coincident with a 20% reduction of North Atlantic Deep Water contribution to the abyssal South Atlantic. These results demonstrate that the glacial deep Atlantic carbon inventory increased by approximately 50 Gt during the transition to 100-kyr glacial cycles. We suggest that the coincidence of our observations with evidence for increased terrestrial ice volume reflects how weaker overturning circulation and Southern Ocean biogeochemical feedbacks facilitated deep ocean carbon storage, which lowered the atmospheric partial pressure of CO2 and thereby enabled expanded terrestrial ice volume at the mid-Pleistocene transition. Deep Atlantic carbon storage increased and the meriodional overturning circulation weakened at the mid-Pleistocene transition to 100,000-year glacial–interglacial cycles, according to analyses of foraminifera trace elements and Nd isotopes.

An efficient morpholinium ionic liquid based catalyst system for cycloaddition of CO2 and epoxides under mild conditions

In recent decades, global warming has affected human society greatly and drawn worldwide attention. CO2 chemical fixation was proved to be a promising methodology in slowing down the warming process, but efforts are still needed to make it more effective and green. Here in, we reported a binary catalyst system composed of morpholinium ionic liquids and zinc bromide. This catalyst could turn CO2 and epoxides into corresponding carbonates quantitatively under extremely mild conditions (R.T., atmospheric CO2 pressure). Since it was environmentally benign and could reduce the carbon footprint, this catalyst would make the cycloaddition reaction a more reliable artificial carbon sink.

Synergistic Ag(I)/nBu4NBr-catalyzed fixation of CO2 to β-oxopropyl carbonates via propargylic alcohols and monohydric alcohols

Chemical fixation of carbon dioxide under mild reaction conditions e.g. atmospheric pressure and low temperature depends upon the ability of catalyst. Herein, a synergistic catalytic scheme of silver sulfadiazine/nBu4NBr was described for the three-component reaction of propargylic alcohols, CO2, and monohydric alcohols. This catalytic system was demonstrated effectively to provide β-oxopropyl carbonates in excellent yields (up to 99% yield with 5 mol% catalyst). The method tolerated a wide scope of propargylic alcohols and monohydric alcohols under atmospheric CO2 pressure and solvent-free conditions. The excellent catalytic performance was attributed to the synergistic catalysis confirmed by the careful experiments.

Copper-Catalyzed C-H Carbamoyloxylation of Aryl Carboxamides with CO2 and Amines at Ambient Conditions.

A copper-catalyzed, 8-aminoquinoline-assisted, one-pot three-component coupling of aryl carboxamides, CO2, and amines has been developed. This protocol proceeds smoothly in the presence of inexpensive CuI and MnO2 at room temperature under atmospheric CO2 pressure, leading to simultaneous construction of C-O and C-N bonds. The reaction displays a broad substrate scope, high functional group tolerance, and excellent monoselectivity, providing an operationally simple method for the synthesis of various O-aryl carbamates.