79-31-2Relevant articles and documents
Time-Dependent Self-Assembly of Copper(II) Coordination Polymers and Tetranuclear Rings: Catalysts for Oxidative Functionalization of Saturated Hydrocarbons
Costa, Ines F. M.,Kirillova, Marina V.,André, Vania,Fernandes, Tiago A.,Kirillov, Alexander M.
supporting information, p. 14491 - 14503 (2021/07/19)
This study describes a time-dependent self-assembly generation of new copper(II) coordination compounds from an aqueous-medium reaction mixture composed of copper(II) nitrate, H3bes biobuffer (N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid), ammonium hydroxide, and benzenecarboxylic acid, namely, 4-methoxybenzoic (Hfmba) or 4-chlorobenzoic (Hfcba) acid. Two products were isolated from each reaction, namely, 1D coordination polymers [Cu3(μ3-OH)2(μ-fmba)2(fmba)2(H2O)2]n (1) or [Cu2(μ-OH)2(μ-fcba)2]n (2) and discrete tetracopper(II) rings [Cu4(μ-Hbes)3(μ-H2bes)(μ-fmba)]·2H2O (3) or [Cu4(μ-Hbes)3(μ-H2bes)(μ-fcba)]·4H2O (4), respectively. These four compounds were obtained as microcrystalline air-stable solids and characterized by standard methods, including the single-crystal X-ray diffraction. The structures of 1 and 2 feature distinct types of metal-organic chains driven by the μ3- or μ-OH- ligands along with the μ-benzenecarboxylate linkers. The structures of 3 and 4 disclose the chairlike Cu4 rings assembled from four μ-bridging and chelating aminoalcoholate ligands along with μ-benzenecarboxylate moieties playing a core-stabilizing role. Catalytic activity of 1-4 was investigated in two model reactions, namely, (a) the mild oxidation of saturated hydrocarbons with hydrogen peroxide to form alcohols and ketones and (b) the mild carboxylation of alkanes with carbon monoxide, water, and peroxodisulfate to generate carboxylic acids. Cyclohexane and propane were used as model cyclic and gaseous alkanes, while the substrate scope also included cyclopentane, cycloheptane, and cyclooctane. Different reaction parameters were investigated, including an effect of the acid cocatalyst and various selectivity parameters. The obtained total product yields (up to 34% based on C3H8 or up to 47% based on C6H12) in the carboxylation of propane and cyclohexane are remarkable taking into account an inertness of these saturated hydrocarbons and low reaction temperatures (50-60 °C). Apart from notable catalytic activity, this study showcases a novel time-dependent synthetic strategy for the self-assembly of two different Cu(II) compounds from the same reaction mixture.
A 3D MOF based on Adamantoid Tetracopper(II) and Aminophosphine Oxide Cages: Structural Features and Magnetic and Catalytic Properties
?liwa, Ewelina I.,Nesterov, Dmytro S.,Kirillova, Marina V.,K?ak, Julia,Kirillov, Alexander M.,Smoleński, Piotr
supporting information, p. 9631 - 9644 (2021/06/30)
This work describes an unexpected generation of a new 3D metal-organic framework (MOF), [Cu4(μ-Cl)6(μ4-O)Cu(OH)2(μ-PTAO)4]n·2nCl-EtOH·2.5nH2O, from copper(II) chloride and 1,3,5-triaza-7-phosphaadamantane 7-oxide (PTAO). The obtained product is composed of diamandoid tetracopper(II) [Cu4(μ-Cl)6(μ4-O)] cages and monocopper(II) [Cu(OH)2] units that are assembled, via the diamandoid μ-PTAO linkers, into an intricate 3D net with an nbo topology. Magnetic susceptibility measurements on this MOF in the temperature range of 1.8-300 K reveal a ferromagnetic interaction (J = +20 cm-1) between the neighboring copper(II) ions. Single-point DFT calculations disclose a strong delocalization of the spin density over the tetranuclear unit. The magnitude of exchange coupling, predicted from the broken-symmetry DFT studies, is in good agreement with the experimental data. This copper(II) compound also acts as an active catalyst for the mild oxidation and carboxylation of alkanes. The present study provides a unique example of an MOF that is assembled from two different types of adamantoid Cu4 and PTAO cages, thus contributing to widening a diversity of functional metal-organic frameworks.
(Hexamethylbenzene)Ru catalysts for the Aldehyde-Water Shift reaction
Phearman, Alexander S.,Moore, Jewelianna M.,Bhagwandin, Dayanni D.,Goldberg, Jonathan M.,Heinekey, D. Michael,Goldberg, Karen I.
supporting information, p. 1609 - 1615 (2021/03/09)
The Aldehyde-Water Shift (AWS) reaction uses H2O as a benign oxidant to convert aldehydes to carboxylic acids, producing H2, a valuable reagent and fuel, as its sole byproduct. (Hexamethylbenzene)RuIIcomplexes are demonstrated to have higher activity and selectivity (up to 95%) for AWS over disproportionation than previously reported catalysts.
Aqueous Persistent Noncovalent Ion-Pair Cooperative Coupling in a Ruthenium Cobaltabis(dicarbollide) System as a Highly Efficient Photoredox Oxidation Catalyst
Guerrero, Isabel,Vi?as, Clara,Fontrodona, Xavier,Romero, Isabel,Teixidor, Francesc
, p. 8898 - 8907 (2021/06/28)
An original cooperative photoredox catalytic system, [RuII(trpy)(bpy)(H2O)][3,3′-Co(1,2-C2B9H11)2]2 (C4; trpy = terpyridine and bpy = bipyridine), has been synthesized. In this system, the photoredox metallacarborane catalyst [3,3′-Co(1,2-C2B9H11)2]- ([1]-) and the oxidation catalyst [RuII(trpy)(bpy)(H2O)]2+ (C2′) are linked by noncovalent interactions and not through covalent bonds. The noncovalent interactions to a large degree persist even after water dissolution. This represents a step ahead in cooperativity avoiding costly covalent bonding. Recrystallization of C4 in acetonitrile leads to the substitution of water by the acetonitrile ligand and the formation of complex [RuII(trpy)(bpy)(CH3CN)][3,3′-Co(1,2-C2B9H11)2]2 (C5), structurally characterized. A significant electronic coupling between C2′ and [1]- was first sensed in electrochemical studies in water. The CoIV/III redox couple in water differed by 170 mV when [1]- had Na+ as a cation versus when the ruthenium complex was the cation. This cooperative system leads to an efficient catalyst for the photooxidation of alcohols in water, through a proton-coupled electron-transfer process. We have highlighted the capacity of C4 to perform as an excellent cooperative photoredox catalyst in the photooxidation of alcohols in water at room temperature under UV irradiation, using 0.005 mol % catalyst. A high turnover number (TON = 20000) has been observed. The hybrid system C4 displays a better catalytic performance than the separated mixtures of C2′ and Na[1], with the same concentrations and ratios of Ru/Co, proving the history relevance of the photocatalyst. Cooperative systems with this type of interaction have not been described and represent a step forward in getting cooperativity avoiding costly covalent bonding. A possible mechanism has been proposed.
Low-Flammable Parahydrogen-Polarized MRI Contrast Agents
Ariyasingha, Nuwandi M.,Chekmenev, Eduard Y.,Chukanov, Nikita V.,Gelovani, Juri G.,Joalland, Baptiste,Koptyug, Igor V.,Kovtunov, Kirill V.,Nantogma, Shiraz,Salnikov, Oleg G.,Younes, Hassan R.
, p. 2774 - 2781 (2021/01/18)
Many MRI contrast agents formed with the parahydrogen-induced polarization (PHIP) technique exhibit biocompatible profiles. In the context of respiratory imaging with inhalable molecular contrast agents, the development of nonflammable contrast agents would nonetheless be highly beneficial for the biomedical translation of this sensitive, high-throughput and affordable hyperpolarization technique. To this end, we assess the hydrogenation kinetics, the polarization levels and the lifetimes of PHIP hyperpolarized products (acids, ethers and esters) at various degrees of fluorine substitution. The results highlight important trends as a function of molecular structure that are instrumental for the design of new, safe contrast agents for in vivo imaging applications of the PHIP technique, with an emphasis on the highly volatile group of ethers used as inhalable anesthetics.
The Size-Accelerated Kinetic Resolution of Secondary Alcohols
P?lloth, Benjamin,Sibi, Mukund P.,Zipse, Hendrik
supporting information, p. 774 - 778 (2020/12/01)
The factors responsible for the kinetic resolution of alcohols by chiral pyridine derivatives have been elucidated by measurements of relative rates for a set of substrates with systematically growing aromatic side chains using accurate competitive linear regression analysis. Increasing the side chain size from phenyl to pyrenyl results in a rate acceleration of more than 40 for the major enantiomer. Based on this observation a new catalyst with increased steric bulk has been designed that gives enantioselectivity values of up to s=250. Extensive conformational analysis of the relevant transition states indicates that alcohol attack to the more crowded side of the acyl-catalyst intermediate is favoured due to stabilizing CH-π-stacking interactions. Experimental and theoretical results imply that enantioselectivity enhancements result from accelerating the transformation of the major enantiomer through attractive non-covalent interactions (NCIs) rather than retarding the transformation of the minor isomer through repulsive steric forces.
Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
, p. 803 - 808 (2021/07/20)
Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
FLOW CHEMISTRY SYNTHESIS OF ISOCYANATES
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Paragraph 0175; 0336-0338, (2021/06/22)
The disclosure provides, inter alia, safe and environmentally-friendly methods, such as flow chemistry, to synthesize isocyanates, such as methylene diphenyl diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and tetramethylxylene diisocyanate.
PROCESSES FOR PRODUCING CARBOXYLIC ACIDS
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Page/Page column 0042, (2020/10/20)
Processes are disclosed for preparing carboxylic acids from organic esters, the processes comprising contacting an ester with water in the presence of an acid catalyst and a homogenizing solvent at conditions effective to form a carboxylic acid. The homogenizing solvent is present in an amount sufficient to form a single-phase reaction mixture comprising the ester, water, and homogenizing solvent. The homogenizing solvent may be selected from acetonitrile, dimethyl sulfoxide, and 1,4-dioxane.
Oxidation of aromatic and aliphatic aldehydes to carboxylic acids by Geotrichum candidum aldehyde dehydrogenase
Hoshino, Tomoyasu,Yamabe, Emi,Hawari, Muhammad Arisyi,Tamura, Mayumi,Kanamaru, Shuji,Yoshida, Keisuke,Koesoema, Afifa Ayu,Matsuda, Tomoko
, (2020/07/20)
Oxidation reaction is one of the most important and indispensable organic reactions, so that green and sustainable catalysts for oxidation are necessary to be developed. Herein, biocatalytic oxidation of aldehydes was investigated, resulted in the synthesis of both aromatic and aliphatic carboxylic acids using a Geotrichum candidum aldehyde dehydrogenase (GcALDH). Moreover, selective oxidation of dialdehydes to aldehydic acids by GcALDH was also successful.
