Ambient CO Pressure Research Articles

Ambient-pressure alkoxycarbonylation for sustainable synthesis of ester

Alkoxycarbonylation reactions are common in the chemical industry, yet process sustainability is limited by the inefficient utilization of CO. In this study, we address this issue and demonstrate that significant improvements can be achieved by adopting a heterogeneously catalyzed process, using a Ru/NbOx catalyst. The Ru/NbOx catalyst enables the direct synthesis of methyl propionate, a key industrial commodity, with over 98% selectivity from CO, ethylene and methanol, without any ligands or acid/base promoters. Under ambient CO pressure, a high CO utilization efficiency (336 mmolestermolCO−1h−1) is achieved. Mechanistic investigations reveal that CO undergoes a methoxycarbonyl (COOCH3) intermediate pathway, attacking the terminal carbon atom of alkene and yielding linear esters. The origins of prevailing linear regioselectivity in esters are revealed. The infrared spectroscopic feature of the key COOCH3 species is observed at 1750 cm−1 (C=O vibration) both experimentally and computationally. The broad substrate applicability of Ru/NbOx catalyst for ester production is demonstrated. This process offers a sustainable and efficient approach with high CO utilization and atom economy for the synthesis of esters.

Ligand-Free Palladium-Catalyzed Substoichiometric Base ­Mediated Carbonylation of Aryl Iodides with Alkenylboronic Acids under Ambient Conditions

AbstractA highly efficient, practical, and ligand-free palladium-catalyzed carbonylation of aryl iodides with alkenylboronic acids has been developed. A variety of chalcones and α-branched enones were isolated in satisfactory to good yields with good substrate compatibilities under an ambient pressure of CO at room temperature. Moreover, the transformation proceeds well in the presence of a substoichiometric amount of base. The merit of this strategy as a late-stage functionalization platform has been demonstrated by modifications of complex substrates derived from estrone and 3-phenyl-l-alanine.

Palladium‐Catalyzed Carbonylative Cross‐Coupling of Aryl Iodides and Alkenyl Bromides with Benzyl Halides under Reductive Conditions

AbstractA direct and convenient method for the palladium‐catalyzed reductive cross‐coupling of aryl iodides or alkenyl bromides and secondary benzyl halides under ambient CO pressure to generate a diverse array of aryl/alkenyl alkyl ketones has been developed. This strategy successfully achieves a three‐component carbonylative reaction with Zn as the reducing agent for C−C bond formation, overcoming the well‐known homocoupling of aryl or alkenyl halides, direct cross‐coupling between two different electrophiles and other carbonylative coupling reactions. In addition, this method avoids use of preformed organometallic nucleophiles, such as organo‐magnesium, zinc and boron reagents. This approach enables the construction of valuable aryl alkyl/alkenyl ketone derivatives (60 examples, 56–95% yields). Reactivity studies indicate that in situ formed benzylic zinc reagents are intermediates in the catalytic system.

Dual Roles of Co2(CO)8 Enable Carbonylative Ring Expansion of Thietane under Ambient CO Pressure

AbstractCobalt‐catalyzed carbonylative ring expansion of thietane under ambient CO pressure was developed, affording a variety of thioacetones in moderate to high yields. dual roles of Co2(CO)8 as the precursor of both carbonylation catalyst and Lewis acid was revealed by control experiments and spectroscopic characterization. The carbonylative ring expansion under CO gas‐free conditions was demonstrated by using Co2(CO)8 as both CO surrogate and pre‐catalyst.

Co2(CO)8-Catalyzed Reactions of Acetals or Lactones with Hydrosilanes and Carbon Monoxide. A New Access to the Preparation of 1,2-Diol Derivatives through Siloxymethylation

Abstract The Co2(CO)8-catalyzed reaction of acetals with hydrosilanes and CO under mild reaction conditions (an ambient temperature under an ambient CO pressure), leading to the production of vicinal diols is reported. A siloxymethyl group can be introduced via the cleavage of one of two alkoxy groups in the acetal. The effects of the types of hydrosilanes, acetals, solvents, and reaction temperatures on the yield of siloxymethylation products were examined in detail. The reactivity for hydrosilanes is as follows; HSiMe3 > HSiEtMe2 > HSiEt2Me > HSiEt3. Hemiacetal esters are more reactive than dimethyl acetals. The polarity of the solvent used also has a significant effect on both the course of the reaction as well as the reaction rate. The site-selective siloxymethylation can be achieved in the case of cyclic acetals such as tetrahydrofuran (THF) and tetrahydropyrane (THP) derivatives, depending on the nature of the oxygen substituent attached adjacent to the oxygen atom in the ring. When 2-alkoxy THF or THP derivatives are used as substrates, the siloxymethylation takes place with cleavage of the ring C-O bond. In contrast, the reaction of 2-acetoxy THF or THP derivatives results in siloxymethylation with the cleavage of C-OAc bond. The ring-opening siloxymethylation of lactones was also examined.

Enhanced Stability of Pt-Cu Single-Atom Alloy Catalysts: In Situ Characterization of the Pt/Cu(111) Surface in an Ambient Pressure of CO

The interaction between a catalyst and reactants often induces changes in the surface structure and composition of the catalyst, which, in turn, affect its reactivity. Therefore, it is important to study such changes using in situ techniques under well-controlled conditions. We have used ambient pressure X-ray photoelectron spectroscopy to study the surface stability of a Pt/Cu(111) single-atom alloy in an ambient pressure of CO. By directly probing the Pt atoms, we found that CO causes a slight surface segregation of Pt atoms at room temperature. In addition, while the Pt/Cu(111) surface demonstrates poor thermal stability in ultrahigh vacuum conditions, where surface Pt starts to diffuse to the subsurface layer above 400 K, the presence of adsorbed CO enhances the thermal stability of surface Pt atoms. However, we also found that temperatures above 450 K cause restructuring of the subsurface layer, which consequently strengthens the CO binding to the surface Pt sites, likely because of the presence of n...

Carbonylative Suzuki cross-coupling reaction catalyzed by bimetallic Pd-Pt nanodendrites under ambient CO pressure

Pd-catalyzed reactions between aryl boronic acids and aryl halides have undergone rapid development since the pioneering work of Suzuki and co-workers in 1979. In this paper, we described a high-efficient and cost-effective bimetallic Pd-Pt nanodendrites catalyst based on a ligand-free strategy to synthesize diaryl ketones via CO direct insertion to boronic acids and aryl halides. A variety of aryl boronic acids and aryl halides were investigated, which showed great functional group tolerance and versatile aryl ketone products in high yield.

Covalent triazine framework-supported palladium as a ligand-free catalyst for the selective double carbonylation of aryl iodides under ambient pressure of CO.

Carbonylation of aryl iodides with amines under atmospheric pressure of CO, catalyzed by Pd/CTFs (covalent triazine frameworks) without any specific additives, leads to the highly selective synthesis of α-ketoamides.

ChemInform Abstract: Copper(I)/Phosphine‐Catalyzed Tandem Carboxylation/Annulation of Terminal Alkynes under Ambient Pressure of CO2: One‐Pot Access to 3a‐Hydroxyisoxazolo[3,2‐a]isoindol‐8(3aH)‐ones.

An efficient method for the synthesis of 3a-hydroxyisoxazolo[3,2-a]isoindol-8(3aH)-ones from CO2, terminal alkynes, EtBr, and NHPI (N-hydroxyphthalimide) was developed through a tandem carboxylation/annulation strategy catalyzed by a copper(I)/phosphine system. This one-pot multicomponent reaction was conducted at atmospheric CO2 pressure to afford the target products in good to excellent yields under mild conditions. Notably, a wide range of functional groups were tolerated in this procedure. This protocol with simultaneous formation of four novel bonds i.e. two C–C bonds and two C–O bonds represents an efficient methodology for upgrading CO2 into heterocycles.

Intermolecular [2+2+1] Carbonylative Cycloaddition of Aldehydes with Alkynes, and Subsequent Oxidation to γ-Hydroxybutenolides by a Supported Ruthenium Catalyst.

Intermolecular [2+2+1] carbonylative cycloaddition of aldehydes with alkynes and subsequent oxidation to γ-hydroxybutenolides is achieved using a supported ruthenium catalyst. A ceria-supported ruthenium catalyst promotes the reaction efficiently, even with an ambient pressure of CO or without external CO, thus giving the corresponding γ-hydroxybutenolide derivatives in good to high yields. Moreover this catalyst can be reused with no loss of activity.

Intermolecular [2+2+1] Carbonylative Cycloaddition of Aldehydes with Alkynes, and Subsequent Oxidation to γ‐Hydroxybutenolides by a Supported Ruthenium Catalyst

AbstractIntermolecular [2+2+1] carbonylative cycloaddition of aldehydes with alkynes and subsequent oxidation to γ‐hydroxybutenolides is achieved using a supported ruthenium catalyst. A ceria‐supported ruthenium catalyst promotes the reaction efficiently, even with an ambient pressure of CO or without external CO, thus giving the corresponding γ‐hydroxybutenolide derivatives in good to high yields. Moreover this catalyst can be reused with no loss of activity.

ChemInform Abstract: Copper‐Catalyzed Carbonylative Suzuki Coupling of Aryl Iodides with Arylboronic Acids under Ambient Pressure of Carbon Monoxide.

An efficient and ligandless nanocopper-catalyzed carbonylative cross-coupling of aryl iodides with arylboronic acids at ambient CO pressure in poly(ethylene glycol), has been developed. This protocol is general, practical, and recyclable, and offers an attractive alternative to the corresponding palladium-mediated carbonylative Suzuki process for the construction of biaryl ketone scaffolds.

In situ generated nickel nanoparticle-catalyzed carbonylative Suzuki reactions of aryl iodides with arylboronic acids at ambient CO pressure in poly(ethylene glycol)

A general in situ generated nickel nanoparticle-catalyzed carbonylative Suzuki reactions of aryl iodides with arylboronic acids at atmospheric CO pressure in poly(ethylene glycol) has been demonstrated. A wide range of aryl iodides and arylboronic acids can be coupled to the corresponding biarylketones with high yields even in the absence of an added ligand and at low catalyst loading. The nature of the active catalytic species is discussed.

Copper-catalyzed carbonylative Suzuki coupling of aryl iodides with arylboronic acids under ambient pressure of carbon monoxide

An efficient and ligandless nanocopper-catalyzed carbonylative cross-coupling of aryl iodides with arylboronic acids at ambient CO pressure in poly(ethylene glycol), has been developed.

ChemInform Abstract: Alkoxycarbonylation Reactions Using Aryl Fluorosulfonates.

Abstract Aryl fluorosulfonates are shown to undergo palladium catalysed alkoxycarbonylation with a variety of alcohols under mild basic conditions at ambient CO pressure.

Pd(0)-catalyzed reaction of alkynes with trifurylgermane and CO providing acylgermanes: the example of hydrometalcarbonylation of alkynes.

A direct synthesis of acylmetals from alkynes with group 14 metal hydride and CO is reported. The Pd(0)-catalyzed reaction of alkynes with tri(2-furyl)germane under ambient pressure of CO provides alpha,beta-unsaturated acylgermanes in good yields. Conversion of acylgermanes to the corresponding amides is achieved.

{M 3S 2} heterometallic aggregates derived from Pt 2(PPh 3) 4( μ-S) 2: structural analysis of [MPt 2X(PPh 3) 5( μ3-S) 2] + (M=Pd and Pt, X=Cl; M=Rh and Ir, X=CO) by X-ray single-crystal crystallography

Heterometallic addition of d 8 complexes of Pd(II), Pt(II), Rh(I) and Ir(I) to Pt 2(PPh 3) 4( μ-S) 2 results in triangular aggregates [MPt 2X(PPh 3) 5( μ 3-S) 2] + (M=Pd and Pt, X=Cl; M=Rh and Ir, X=CO) characterized by 31P-NMR spectroscopy and X-ray single-crystal crystallography. They show a trigonal bipyramidal {MPt 2S 2} core with three d 8 sq-planar metal atoms aligned at close proximity but without direct M–M bonds. Unlike their d 10 counterparts [Ag(I) and Cu(I)], these aggregates resist desulfurization under ambient pressure of CO.

HREELS study on the effect of iodine on the bonding of CO on Rh(111)

The adsorption of CO on I-covered Rh(111) surface has been investigated by TDS and HREELS. Adsorbed iodine was produced by decomposition of adsorbed CH 3I. The uptake of CO significantly decreased in the presence of I adlayer. At high I coverage ( Θ I=0.33) the maximum amount of CO adsorbed was only one third of that measured for clean Rh(111). Preadsorbed I lowered the stability of adsorbed CO. HREELS measurements revealed that the I adlayer reduced the intensity of the vibration loss for the on-top bonded CO and caused a new loss feature at 1700–1800 cm −1 due to the bridge-bonded CO. At ambient CO pressure, a high frequency CO peak was detected by RAIRS, which was attributed to a short range CO–I interaction.

Alkoxycarbonylation Reactions Using Aryl Fluorosulfonates

Abstract Aryl fluorosulfonates are shown to undergo palladium catalysed alkoxycarbonylation with a variety of alcohols under mild basic conditions at ambient CO pressure.

Adsorption-desorption kinetics of carbon monoxide on a palladium (100) single crystal surface modified with sulfur

The thermal desorption spectra, the adsorption isotherms, and the absolute rates of adsorption and desorption of carbon monoxide were measured on the (100) plane of palladium modified with sulfur adatoms. A small amount of S adatoms reduced the thermal desorption energy from ~ 34 kcal mol −1 to ~ 9 kcal mol −1. During adsorption, the absolute desorption rate increased with increasing ambient CO pressure. This kind of pressure dependency was depressed by a quarter monolayer of S. The absolute adsorption rate as a function of CO coverage did not depend on the crystal temperature of the clean surface, but it showed a negative temperature-dependence with increasing sulfur coverage.