24704-57-2Relevant academic research and scientific papers
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.
On the solvolysis kinetics of amidoesters derived from β-aminoalcohols
Hankins, Jamilah N.,Gouws, Michele,Mahajer, Amir,Kim, Ethan S.,Gwaltney, Kevin P.,Haseltine, John
, p. 2450 - 2453 (2012)
To better understand reactivity in such systems, fifteen amidoesters derived from β-aminoalcohols were solvolyzed at the ester group in mildly basic methanol-d4. All trials showed pseudo-first-order kinetics by 1H NMR. The rate constants are about 2 to 140-fold larger than those found with simple alkyl esters. The least bulky N-acyl groups generally sponsor the largest rate constants, and strongly so in two cases, but apparently not as a result of lesser steric crowding between the amide and ester groups. Rate constants are also greater for those amidoesters favoring an anti conformation at the amide linkage.
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.
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.
Oxidative functionalization of methane in the presence of a homogeneous rhodium-copper-chloride catalytic system: Transformation of acetic and propionic acids as solvent components
Chepaikin,Bezruchenko,Menchikova,Moiseeva,Gekhman,Moiseev
scheme or table, p. 133 - 142 (2012/01/13)
The oxidative functionalization of methane (O2, CO, 95°C, Rh III/CuI, II/Cl- catalytic system) was studied in an aqueous acetic or propionic acid medium. It was shown that oxidative decarbonylation of carboxylic acids takes place along with methanol and methyl carboxylate formation.
Structure dependence in the solvolysis kinetics of amino acid esters
Haseltine, John,Runyon, Jason W.
scheme or table, p. 3280 - 3283 (2010/07/18)
To better understand acyl transfer reactions of oligopeptides, seventeen N-acyl amino acid esters were solvolyzed in mildly basic methanol-d4. All show pseudo-first-order kinetics by 1H NMR. The rate constant varies up to 400-fold with the identity of the amino acid and up to 6200-fold with the identity of the N-acyl group. The impact of the N-acyl group on the rate constant is discussed in terms of crowding, amide conformation, and amide C{double bond, long}O bond character.
Gold-catalyzed oxidative cleavage of aryl-substituted alkynyl ethers using molecular oxygen. Simultaneous degradation of C-H and single and triple carbon-carbon bonds under ambient conditions
Das, Arindam,Chaudhuri, Rupsha,Liu, Rai-Shung
scheme or table, p. 4046 - 4048 (2009/12/08)
We report the gold-catalyzed oxidative cleavage of aryl-substituted alkynyl ethers using molecular oxygen under ambient conditions; the transformation involves a remarkable cleavage of C-H, C-C and CC bonds simultaneously.
Concave reagents: Part 40 - The copper(ii) complex of a concave reagent as a selective catalyst for ester methanolysis
Cacciapaglia, Roberta,Di Stefano, Stefano,Fahrenkrug, Frank,Luening, Ulrich,Mandolini, Luigi
, p. 350 - 355 (2007/10/03)
We have shown that the CuII complexes of the concave ligand 1 and its model compound 2 are efficient catalysts of ester methanolysis under conditions close to neutrality. Turnover catalysis without product inhibition was demonstrated by the clean first-order release of a greater than stoichiometric amount of product. Compared with background methanolysis, the metal catalysts give greater rate accelerations for methyl acetate methanolysis than for the p-nitrophenyl acetate methanolysis. Analysis of electronic and steric effects on rates of metal-mediated vs metal-free methoxide addition to the esters has provided compelling evidence that transfer of methoxide from the metal to the carbonyl carbon is accompanied by extensive Lewis acid activation of the carbonyl via a four-membered chelate transition state that includes the metal ion. Copyright
Catalysis of transesterification reactions by lanthanides - Unprecedented acceleration of methanolysis of aryl and alkyl esters promoted by La(OTf)3 at neutral sspH and ambient temperatures
Neverov, Alexei A.,McDonald, Todd,Gibson, Graham,Brown
, p. 1704 - 1710 (2007/10/03)
La3+ catalysis of the methanolysis of the esters p-nitrophenyl, 2,4-dinitrophenyl, and phenyl acetate (1-3), phenyl benzoate (4), and ethyl, i-propyl, cyclohexyl, and tert-butyl acetate (5, 6a, 6b, 7) was studied at 25°C as a function of sspH and [La(OTf)3]. The active form of the catalyst is attributed to a dimethoxy-bridged dimer of stoichiometry (La3+)2(-OCH3)2, having maximum activity atsspH 8 to 9. For preparative reactions, the active catalyst can be made in situ simply by adding 0.01 equiv of La(OTf)3, and 0.01 equiv of NaOCH3 to a methanol solution containing the ester (1 M). Strong catalysis of methanolysis of both aryl and alkyl esters was observed, although tert-butyl acetate was inert. At sspH 8.5, where the catalyst is maximally active, the transesterification reactions are accelerated by 40 000-fold to 18 000 000-fold in the presence of as little as 5 mM catalyst relative to the background reaction depending on the ester structure. A mechanism for catalysis of transesterification is presented wherein the reactive species is generated by breaking a single La-OCH3 bond of the dimethoxy-bridged dimer to reveal a nucleophilic metal-bound methoxide - Lewis acid La3+ electrophilic pair.
Analysis of the Mechanism of Photolysis of Methanol-d4 Solutions of Acetylpropionyl Peroxide With the Use of Chemically Induced Dynamic Nuclear Polarization
Skakovskii, E. D.,Stankevich, A. I.,Lamotkin, S. A.,Tychinskaya, L. Yu.,Avrinskii, G. S.,Rykov, S. V.
, p. 770 - 777 (2007/10/03)
On the basis of the effects of chemically induced dynamic nuclear polarization of 1H and 13C and the yields of reaction products, the photolysis of methanol-d4 solutions of acetylpropionyl peroxide is investigated within the. temperature interval 193-333
