Accelerated reactions of amines with carbon dioxide driven by superacid at the microdroplet interface.

This paper is part of a larger investigation of the role of amines in the adhesion of polybutadiene to glass substrates. It describes near infrared, infrared and nuclear magnetic resonance spectroscopy studies of the interaction of amines with silanol groups usually under ambient conditions but sometimes when heated in air. Additional supporting evidence was obtained from gas liquid chromatography, mass spectrometry and elemental analyses. In order to assure a sufficiently high concentration of silanol groups, triethylsilanol and fused silica were used as models for the glass surface. The mechanism of interaction of aliphatic amines and of the aminosilane was different from that of aromatic amines. Most notably, reaction of aliphatic amines with carbon dioxide in the air and/or dissolved/adsorbed in/on the silanol occurred almost instantaneously, whereas the corresponding reaction of the aromatic amines with carbon dioxide was not observed under the experimental conditions used. The carbamates formed underwent further reactions much more rapidly than either the simple aromatic amines or the unmodified aliphatic amines.

DFT calculations indicate that the key activation barriers in the reaction of ethylene oxide and amines play an important role in determining the yields of products.

Sprayed water microdroplets act as open-air microreactors, unlocking reaction pathways that are often inaccessible in bulk solution. Here, we present that aerosolizing aqueous solutions of reducing sugars (d-glucose and l-fructose) spontaneously yield 5-hydroxymethylfurfural (HMF), a versatile platform chemical for biofuels, bioplastics, and pharmaceuticals. Mechanistic studies reveal that the super acidic and "water-starved microenvironment" at the microdroplet interface intrinsically activates sugars, driving the sequential loss of three water molecules via cyclic or acyclic pathways to form HMF. The reaction proceeds without the need for external reagents, catalysts, heat, or harsh conditions, unlike bulk-phase processes required for HMF production. The facile formation of HMF from glucose in water microdroplets under ambient conditions not only offers a sustainable route to a renewable chemical building block but also provides prebiotic insight, highlighting how such interfacial chemistry could have contributed to the molecular diversity essential for the origin of life.

Water microdroplets containing 100 μM HAuCl4 have been shown to reduce gold ions into gold nanoparticles spontaneously. It has been suggested that this chemical transformation takes place exclusively at the air-water interface of microdroplets, albeit without mechanistic insights. We compared the fate of several metallic salts in water, methanol, ethanol, and acetonitrile in the bulk phase and microdroplet geometry (sprays). Experiments revealed that when HAuCl4 (or PtCl4) is added to bulk water (or methanol or ethanol), metal NPs appear spontaneously. Over time, the nanoparticles grow, evidenced by the bulk solutions' changing colors. If the bulk solution is sprayed pneumatically and microdroplets are collected, the NP size distribution is not significantly enhanced. We find that the reduction of metal ions is accompanied by the oxidation of water (or alcohols); however, these redox reactions are minimal in acetonitrile. This establishes that the spontaneous reduction of metal ions is (i) a bulk phase phenomenon in water and several non-aqueous solutions, (ii) minimally affected by the air-water interface or the microdroplet geometry, and (iii) is not limited to Au3+ ions and can be explained via the electrochemical series. These results advance our understanding of aquatic chemistry and liquids in general and should be relevant in soil chemistry, biogeochemistry, electrochemistry, and green chemistry.

AIM: We have recently developed a microscopic Monte Carlo approach to study surface chemistry on interstellar grains and the morphology of ice mantles. The method is designed to eliminate the problems inherent in the rate-equation formalism to surface chemistry. Here we report the first use of this method in a chemical model of cold interstellar cloud cores that includes both gas-phase and surface chemistry. The surface chemical network consists of a small number of diffusive reactions that can produce molecular oxygen, water, carbon dioxide, formaldehyde, methanol and assorted radicals. METHOD: The simulation is started by running a gas-phase model including accretion onto grains but no surface chemistry or evaporation. The starting surface consists of either flat or rough olivine. We introduce the surface chemistry of the three species H, O and CO in an iterative manner using our stochastic technique. Under the conditions of the simulation, only atomic hydrogen can evaporate to a significant extent. Although it has little effect on other gas-phase species, the evaporation of atomic hydrogen changes its gas-phase abundance, which in turn changes the flux of atomic hydrogen onto grains. The effect on the surface chemistry is treated until convergence occurs. We neglect all non-thermal desorptive processes. RESULTS: We determine the mantle abundances of assorted molecules as a function of time through 2x10^5 yr. Our method also allows determination of the abundance of each molecule in specific monolayers. The mantle results can be compared with observations of water, carbon dioxide, carbon monoxide, and methanol ices in the sources W33A and Elias 16. Other than a slight underproduction of mantle CO, our results are in very good agreement with observations.

The stereoselective synthesis of (E)-bromovinyloxazolidinones was developed by the three-component reaction of propargylic amines, carbon dioxide, and N-bromosuccinimide in the presence of a silver...

A Cu-catalyzed oxidative coupling reaction of arylboronic acids, amines and carbon dioxide is described, providing a route to O-aryl carbamates.

Noble metal free double helix binuclear Cu(I) complex as catalyst for carboxylative cyclization of propargylamines with atmospheric carbon dioxide toward oxazolidinones synthesis under mild conditions

The transformation of carbon dioxide into value-added fine chemicals via homogeneous catalysis has gained much attention since carbon dioxide is an abundant, nontoxic, and inexpensive C1 feedstock. Silver catalysis has emerged as important synthetic methods for a wide range of organic transformations in the last two decades. In silver-catalyzed carboxylation reactions using carbon dioxide as a carboxylative reagent, silver(I) salts or complexes generally serve as a π-Lewis acid catalyst to activate unsaturated systems, especially alkynes, or in situ generate silver acetylides or arylsilver intermediates as reactive carbon nucleophiles. In this chapter, silver-catalyzed cyclization reactions of propargylic alcohols or amines, o-alkynylanilines, and alkynyl ketones with carbon dioxide are reviewed. Also, silver-catalyzed carboxylation of terminal alkynes and arylboronic esters with carbon dioxide is documented.

Carbamates (N-carboxy derivatives) are formed when solutions of primary or secondary amino compounds in strong alkali are exposed on paper strips to carbon dioxide, and may be separated by paper ionophoresis and detected as additional, anionic components. The formation of mono-, di-, tricarbamates, and so on, from a polyamino compound occurs concurrently, and when an amino compound containing n reactive groups is submitted to paper ionophoresis in 0.lN sodium hydroxide at 18-20° after exposure to carbon dioxide, it affords n additional spots. Most primary and secondary amino groups in saturated compounds, and some aromatic amino groups, are reactive, but highly hindered amino groups are not. Some unreactive groups become reactive when the ionophoresis is conducted at 1-2°. The procedure is analytically useful, and may be used to gain information about the structure of amino compounds. The conditions favouring the formation of carbamates have been defined by paper ionophoresis. The primary reaction in the formation of carbamates is the addition of carbon dioxide to the amino nitrogen atom; carbamates are not formed directly from the carbonate ion. The rate of reaction with carbon dioxide and the stability of the carbamates may be correlated with the steric and electronic environment of the amino groups. Low temperature and high alkalinity are essential for the stability of carbamates in solution. The "basic mercury carbamates" described by Neuberg and Kerb (Biochem. Z., 1912, 40, 498) do not seem to have the structure assigned by these authors. Dithiocarbamates obtained by reaction of amines with carbon disulphide in alkaline solution are easily identified by paper ionophoresis, but they cannot readily be formed on the paper strip. Attempts to prepare N-sulphinates by reaction of amino compounds with sulphur dioxide on paper strips have been unsuccessful.

The kinetic Monte Carlo method as a way to solve the master equation for interstellar grain chemistry.

Interfaces or phase boundaries are a unique chemical environment relative to individual gas, liquid, or solid phases. Interfacial reaction mechanisms and kinetics are often at variance with homogeneous chemistry due to mass transfer, molecular orientation, and catalytic effects. Aqueous interfaces are a common subject of environmental science and engineering research, and three environmentally relevant aqueous interfaces are investigated in this thesis: 1) fluorochemical sonochemistry (bubble-water), 2) aqueous aerosol ozonation (gas-water droplet), and 3) electrolytic hydrogen production and simultaneous organic oxidation (water-metal/semiconductor). Direct interfacial analysis under environmentally relevant conditions is difficult, since most surface-specific techniques require relatively ‘extreme’ conditions. Thus, the experimental investigations here focus on the development of chemical reactors and analytical techniques for the completion of time/concentration-dependent measurements of reactants and their products. Kinetic modeling, estimations, and/or correlations were used to extract information on interfacially relevant processes. We found that interfacial chemistry was determined to be the rate-limiting step to a subsequent series of relatively fast homogeneous reactions, for example: 1) Pyrolytic cleavage of the ionic headgroup of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) adsorbed to cavitating bubble-water interfaces during sonolysis was the rate-determining step in transformation to their inorganic constituents carbon monoxide, carbon dioxide, and fluoride; 2) ozone oxidation of aqueous iodide to hypoiodous acid at the aerosol-gas interface is the rate-determining step in the oxidation of bromide and chloride to dihalogens; 3) Electrolytic oxidation of anodic titanol surface groups is rate-limiting for the overall oxidation of organics by the dichloride radical. We also found chemistry unique to the interface, for example: 1) Adsorption of dilute PFOS(aq) and PFOA(aq) to acoustically cavitating bubble interfaces was greater than equilibrium expectations due to high-velocity bubble radial oscillations; 2) Relative ozone oxidation kinetics of aqueous iodide, sulfite, and thiosulfate were at variance with previously reported bulk aqueous kinetics; 3) Organics that directly chelated with the anode surface were oxidized by direct electron transfer, resulting in immediate carbon dioxide production but slower overall oxidation kinetics. Chemical reactions at aqueous interfaces can be the rate-limiting step of a reaction network and often display novel mechanisms and kinetics as compared to homogeneous chemistry.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetal atom chemistry and surface chemistry: (carbon dioxide)silver, Ag(CO2). A localized bonding model for weakly chemisorbed carbon dioxide on bulk silverGeoffrey A. Ozin, Helmut Huber, and Douglas McIntoshCite this: Inorg. Chem. 1978, 17, 6, 1472–1476Publication Date (Print):June 1, 1978Publication History Published online1 May 2002Published inissue 1 June 1978https://doi.org/10.1021/ic50184a016RIGHTS & PERMISSIONSArticle Views378Altmetric-Citations39LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (614 KB) Get e-Alerts Get e-Alerts

In this work, a series of highly porous sulfur-doped carbons are prepared through physical activation methods by using polythiophene as a precursor. The morphology, structure, and physicochemical properties are revealed by a variety of characterization methods, such as scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and nitrogen sorption measurement. Their porosity parameters and chemical compositions can be well-tuned by changing the activating agents (steam and carbon dioxide) and reaction temperature. These sulfur-doped porous carbons possess specific surface area of 670-2210 m2 g-1, total pore volume of 0.31-1.26 cm3 g-1, and sulfur content of 0.6-4.9 atom %. The effect of porosity parameters and surface chemistry on carbon dioxide adsorption in sulfur-doped porous carbons is studied in detail. After a careful analysis of carbon dioxide uptake at different temperatures (273 and 293 K), pore volumes from small pore size (less than 1 nm) play an important role in carbon dioxide adsorption at 273 K, whereas surface chemistry is the key factor at a higher adsorption temperature or lower relative pressure. Furthermore, sulfur-doped porous carbons also possess good gas adsorption selectivity and excellent recyclability for regeneration.

Via Ammonium Carbamates by Reaction of Amines and Carbon Dioxide