24704-57-2Relevant articles and documents
Stepwise Iodide-Free Methanol Carbonylation via Methyl Acetate Activation by Pincer Iridium Complexes
Yoo, Changho,Miller, Alexander J. M.
, p. 12633 - 12643 (2021)
Iodide is an essential promoter in the industrial production of acetic acid via methanol carbonylation, but it also contributes to reactor corrosion and catalyst deactivation. Here we report that iridium pincer complexes mediate the individual steps of methanol carbonylation to methyl acetate in the absence of methyl iodide or iodide salts. Iodide-free methylation is achieved under mild conditions by an aminophenylphosphinite pincer iridium(I) dinitrogen complex through net C-O oxidative addition of methyl acetate to produce an isolable methyliridium(III) acetate complex. Experimental and computational studies provide evidence for methylation via initial C-H bond activation followed by acetate migration, facilitated by amine hemilability. Subsequent CO insertion and reductive elimination in methanol solution produced methyl acetate and acetic acid. The net reaction is methanol carbonylation to acetic acid using methyl acetate as a promoter alongside conversion of an iridium dinitrogen complex to an iridium carbonyl complex. Kinetic studies of migratory insertion and reductive elimination reveal essential roles of the solvent methanol and distinct features of acetate and iodide anions that are relevant to the design of future catalysts for iodide-free carbonylation.
Uncommon oxidative transformations of acetic and propionic acids
Chepaikin,Bezruchenko,Menchikova,Moiseeva,Gekhman,Moiseev
scheme or table, p. 49 - 54 (2011/09/15)
The oxidative decarbonylation of acetic and propionic acids with the formation of the corresponding alcohol and alkyl carboxylate is observed in the RhIII/CuI,II/Cl- catalytic system in the presence of O2 and CO. The decarbonylation of propionic acid in a deuterated solvent results in the substitution of hydrogen atoms by deuterium in the alkyl part of the products to form CH2DCOOD (CHD 2COOH) and CHD2COOD (CD3COOH). The subsequent decarbonylation of deuterated acetic acids affords the corresponding deuteromethanols detected as esters with propionic and deuteroacetic acids. The substitution of the hydrogen atom by deuterium in the alkyl part of molecules of the products of oxidative decarbonylation of propionic acid, when the reaction is carried out in a deuterated solvent, indicates that propionic acid behaves as saturated hydrocarbon and blocks the oxidation of poorly soluble methane. Unlike propionic acid, acetic acid enters only the oxidative decarbonylation reaction and does not block methane oxidation.
Divergent synthesis and chemical reactivity of bicyclic lactone fragments of complex rearranged spongian diterpenes
Schnermann, Martin J.,Beaudry, Christopher M.,Genung, Nathan E.,Canham, Stephen M.,Untiedt, Nicholas L.,Karanikolas, Breanne D. W.,Suetterlin, Christine,Overman, Larry E.
supporting information; experimental part, p. 17494 - 17503 (2011/12/04)
The synthesis and direct comparison of the chemical reactivity of the two highly oxidized bicyclic lactone fragments found in rearranged spongian diterpenes (8-substituted 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one and 6-substituted 7-acetoxy-2,8-dioxabicyclo[3.3.0]octan-3-one) are reported. Details of the first synthesis of the 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3- one ring system, including an examination of several possibilities for the key bridging cyclization reaction, are described. In addition, the first synthesis of 7-acetoxy-2,8-dioxabicyclo[3.3.0]octanones containing quaternary carbon substituents at C6 is disclosed. Aspects of the chemical reactivity and Golgi-modifying properties of these bicyclic lactone analogs of rearranged spongian diterpenes are also reported. Under both acidic and basic conditions, 8-substituted 2,7-dioxabicyclo[3.2.1]octanones are converted to 6-substituted-2,8-dioxabicyclo[3.3.0]octanones. Moreover, these dioxabicyclic lactones react with primary amines and lysine side chains of lysozyme to form substituted pyrroles, a conjugation that could be responsible for the unique biological properties of these compounds. These studies demonstrate that acetoxylation adjacent to the lactone carbonyl group, in either the bridged or fused series, is required to produce fragmented Golgi membranes in the pericentriolar region that is characteristic of macfarlandin E.
