60-35-5Relevant articles and documents
The 3rd degree of biomimetism: Associating the cavity effect, ZnII coordination and internal base assistance for guest binding and activation
Parrot,Collin,Bruylants,Reinaud
, p. 5479 - 5487 (2018)
The synthesis and characterization of a resorcinarene-based tetra(imidazole) ligand is reported. The properties of the corresponding ZnII complex are studied in depth, notably by NMR spectroscopy. In MeCN, acid-base titration reveals that one out of the four imidazole arms is hemi-labile and can be selectively protonated, thereby opening a coordination site in the exo position. Quite remarkably, the 4th imidazole arm promotes binding of an acidic molecule (a carboxylic acid, a β-diketone or acetamide), by acting as an internal base, which allows guest binding as an anion to the metal center in the endo position. Most importantly, the presence of this labile imidazole arm makes the ZnII complex active for the catalyzed hydration of acetonitrile. It is proposed that it acts as a general base for activating a water molecule in the vicinity of the metal center during its nucleophilic attack to the endo-bound MeCN substrate. This system presents a unique degree of biomimetism when considering zinc enzymes: a pocket for guest binding, a similar first coordination sphere, a coordination site available for water activation in the cis position relative to the substrate and finally an internal imidazole residue that plays the role of a general base.
Swift, E. H.,Butler, E. A.
, p. 146 - 153 (1956)
Measurement and calculation of the rate constant for the reaction of isopropyl isocyanate with hydroxyl radical
Parker, James K.,Espada-Jallad, Cyntia,Parker, Claudia L.,Witt, John D.
, p. 187 - 197 (2009)
The rate constant for the gas-phase reaction of hydroxyl radical with isopropyl isocyanate (IIC) has been measured, relative to toluene, in the T =287-321 K range at atmospheric pressure in air. Ultraviolet photolysis of methyl nitrite served as the sourc
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Paul
, (1937)
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EXAFS/FTIR Characterization and Selective Hydration of Acetonitrile on Silica-Supported *)4V6O19>
Yamaguchi, Masatsugu,Shido, Takafumi,Ohtani, Hiroko,Isobe, Kiyoshi,Ichikawa, Masaru
, p. 717 - 718 (1995)
Silica-supported *)4V6O19 exhibited high catalytic activities in the gas-phase hydration of acetonitrile towards acetamide at 350-473 K with selectivity of over 97percent and dehydrogenation of 2-propanol to acetone.EXAFS, XPS and FTIR studies suggested that thermal evacuation of silica-supported *)4V6O19> at 473 K led to the removal of the bridged oxygen atoms in the V6O19 framework.The resulting deoxygenated samples enhanced the acetonitrile hydration, while catalyzed the dehydration of 2-propanol to propene besides the dehydrogenation reaction, probably owing to the newly generated Lewis acid site.
Karrer,Haab
, p. 950,956 (1949)
Catalytic hydration of benzonitrile and acetonitrile using nickel(0)
Crestani, Marco G.,Arevalo, Alma,Garcia, Juventino J.
, p. 732 - 742 (2006)
The homogeneous catalytic hydration of benzo- and acetonitrile under thermal conditions was achieved using nickel(0) compounds of the type [(dippe)Ni(η2-NCR)] with R = phenyl or methyl (compounds 1 and 2, respectively), as the specific starting intermediates. Alternatively, the complexes may be prepared in situ by direct reaction of the precursor [(dippe)NiH]2 (3) with the respective nitrile. Hydration appears to occur homogeneously, as tested by mercury drop experiments, producing benzamide and acetamide, respectively. Addition of Bu4NI did not lead to catalysis inhibition, suggesting the prevalence of Ni(0) intermediates during catalysis. Hydration using analogous complexes of 3, such as [(dtbpe)NiH] 2 (4) and [(dcype)NiH]2 (5) was also addressed.
Unmasking the Action of Phosphinous Acid Ligands in Nitrile Hydration Reactions Catalyzed by Arene-Ruthenium(II) Complexes
Tomás-Mendivil, Eder,Cadierno, Victorio,Menéndez, María I.,L?pez, Ram?n
, p. 16874 - 16886 (2015)
The catalytic hydration of benzonitrile and acetonitrile has been studied by employing different arene-ruthenium(II) complexes with phosphinous (PR2OH) and phosphorous acid (P(OR)2OH) ligands as catalysts. Marked differences in activity were found, depending on the nature of both the P-donor and η6-coordinated arene ligand. Faster transformations were always observed with the phosphinous acids. DFT computations unveiled the intriguing mechanism of acetonitrile hydration catalyzed by these arene-ruthenium(II) complexes. The process starts with attack on the nitrile carbon atom of the hydroxyl group of the P-donor ligand instead of on a solvent water molecule, as previously suggested. The experimental results presented herein for acetonitrile and benzonitrile hydration catalyzed by different arene-ruthenium(II) complexes could be rationalized in terms of such a mechanism.
Hydration of Aliphatic Nitriles Catalyzed by an Osmium Polyhydride: Evidence for an Alternative Mechanism
Babón, Juan C.,Esteruelas, Miguel A.,López, Ana M.,O?ate, Enrique
, p. 7284 - 7296 (2021/05/29)
The hexahydride OsH6(PiPr3)2 competently catalyzes the hydration of aliphatic nitriles to amides. The main metal species under the catalytic conditions are the trihydride osmium(IV) amidate derivatives OsH3{κ2-N,O-[HNC(O)R]}(PiPr3)2, which have been isolated and fully characterized for R = iPr and tBu. The rate of hydration is proportional to the concentrations of the catalyst precursor, nitrile, and water. When these experimental findings and density functional theory calculations are combined, the mechanism of catalysis has been established. Complexes OsH3{κ2-N,O-[HNC(O)R]}(PiPr3)2 dissociate the carbonyl group of the chelate to afford κ1-N-amidate derivatives, which coordinate the nitrile. The subsequent attack of an external water molecule to both the C(sp) atom of the nitrile and the N atom of the amidate affords the amide and regenerates the κ1-N-amidate catalysts. The attack is concerted and takes place through a cyclic six-membered transition state, which involves Cnitrile···O-H···Namidate interactions. Before the attack, the free carbonyl group of the κ1-N-amidate ligand fixes the water molecule in the vicinity of the C(sp) atom of the nitrile.
A CO2-mediated base catalysis approach for the hydration of triple bonds in ionic liquids
Han, Buxing,Ke, Zhengang,Li, Ruipeng,Liu, Zhimin,Tang, Minhao,Wang, Yuepeng,Zeng, Wei,Zhang, Fengtao,Zhao, Yanfei
supporting information, p. 9870 - 9875 (2021/12/27)
Herein, we report a CO2-mediated base catalysis approach for the activation of triple bonds in ionic liquids (ILs) with anions that can chemically capture CO2 (e.g., azolate, phenolate, and acetate), which can achieve hydration of triple bonds to carbonyl chemicals. It is discovered that the anion-complexed CO2 could abstract one proton from proton resources (e.g., IL cation) and transfer it to the CN or CC bonds via a six-membered ring transition state, thus realizing their hydration. In particular, tetrabutylphosphonium 2-hydroxypyridine shows high efficiency for hydration of nitriles and CC bond-containing compounds under a CO2 atmosphere, affording a series of carbonyl compounds in excellent yields. This catalytic protocol is simple, green, and highly efficient and opens a new way to access carbonyl compounds via triple bond hydration under mild and metal-free conditions.
Metal-Free Solvent Promoted Oxidation of Benzylic Secondary Amines to Nitrones with H2O2
Adrio, Javier,Amarante, Giovanni Wilson,Granato, álisson Silva
, p. 13817 - 13823 (2021/10/01)
An environmentally benign protocol for the generation of nitrones from benzylic secondary amines via catalyst-free oxidation of secondary amines using H2O2 in MeOH or CH3CN is described. This methodology provides a selective access to a variety of C-aryl nitrones in yields of 60 to 93%. Several studies have been performed to shed light on the reaction mechanism and the role of the solvent.
