- Sustainable catalysts for methanol carbonylation
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Methanol carbonylation is the most important process for manufacturing C2 molecules from methanol. The present industrial carbonylation has been proven to be the most successful process on economical grounds. However, there is a request to develop more sustainable and 'green' processes to overcome the inherent drawbacks. Well-designed cross-linked copolymers were prepared and used as support for the simultaneous immobilization of rhodium and iodide species. The resulting catalyst was proven to be highly active in CH3I-free methanol carbonylation and methyl acetate was the main product. Approximately 90% of methanol was converted after a two-hour reaction time at 120 °C under a CO pressure of 3.0 MPa. The immobilization strategy of the active species works efficiently and the present methanol carbonylation catalyst shows good recyclability. After regenerating the catalyst twice over a fifteen-batches test, the catalyst keeps an acceptable activity. The process based on the present catalyst is evidently a promising sustainable methanol carbonylation.
- Li, Fengbo,Chen, Bingfeng,Huang, Zhijun,Lu, Tao,Yuan, Yin,Yuan, Guoqing
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- Ketyl radical reactivity via atom transfer catalysis
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Single-electron reduction of a carbonyl to a ketyl enables access to a polarity-reversed platform of reactivity for this cornerstone functional group. However, the synthetic utility of the ketyl radical is hindered by the strong reductants necessary for its generation, which also limit its reactivity to net reductive mechanisms.We report a strategy for net redox-neutral generation and reaction of ketyl radicals.The in situ conversion of aldehydes to a-acetoxy iodides lowers their reduction potential by more than 1 volt, allowing for milder access to the corresponding ketyl radicals and an oxidative termination event. Upon subjecting these iodides to a dimanganese decacarbonyl precatalyst and visible light irradiation, an atom transfer radical addition (ATRA) mechanism affords a broad scope of vinyl iodide products with high Z-selectivity.
- Wang, Lu,Lear, Jeremy M.,Rafferty, Sean M.,Fosu, Stacy C.,Nagib, David A.
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- Cross-Selective Aza-Pinacol Coupling via Atom Transfer Catalysis
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A cross-selective aza-pinacol coupling of aldehydes and imines has been developed to afford valuable β-amino alcohols. This strategy enables chemoselective conversion of aliphatic aldehydes to ketyl radicals, in the presence of more easily reduced imines and other functional groups. Upon carbonyl-specific activation by AcI, a photoinitiated Mn catalyst selectively reduces the resulting α-oxy iodide by an atom transfer mechanism. The ensuing ketyl radical selectively couples to imines, precluding homodimerization by a classical reductive approach. In this first example of reductive, ketyl coupling by atom transfer catalysis, Zn serves as a terminal reductant to facilitate Mn catalyst turnover. This new strategy also enables ketyl radical couplings to alkenes, alkynes, aldehydes, propellanes, and chiral imines.
- Nagib, David A.,Rafferty, Sean M.,Rutherford, Joy E.,Wang, Lu,Zhang, Lumin
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supporting information
p. 5622 - 5628
(2021/05/07)
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- Mapping-Out Catalytic Processes in a Metal–Organic Framework with Single-Crystal X-ray Crystallography
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Single-crystal X-ray crystallography is employed to characterize the reaction species of a full catalytic carbonylation cycle within a MnII-based metal–organic framework (MOF) material. The structural insights explain why the Rh metalated MOF is catalytically competent toward the carbonylation of MeBr but only affords stoichiometric turn-over in the case of MeI. This work highlights the capability of MOFs to act as platform materials for studying single-site catalysis in heterogeneous systems.
- Burgun, Alexandre,Coghlan, Campbell J.,Huang, David M.,Chen, Wenqian,Horike, Satoshi,Kitagawa, Susumu,Alvino, Jason F.,Metha, Gregory F.,Sumby, Christopher J.,Doonan, Christian J.
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supporting information
p. 8412 - 8416
(2017/07/11)
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- A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
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α-Chloro-, bromo- and iodoenamines, which are readily prepared from the corresponding isobutyramides have been found to be excellent reagents for the transformation of a wide variety of alcohols or carboxylic acids into the corresponding halides. Yields are high and conditions are very mild thus allowing for the presence of sensitive functional groups. The reagents can be easily tuned allowing therefore the selective monohalogenation of polyhydroxylated molecules. The scope and chemoselectivity of the reactions have been studied and reaction mechanisms have been proposed.
- Munyemana, Fran?ois,George, Isabelle,Devos, Alain,Colens, Alain,Badarau, Eduard,Frisque-Hesbain, Anne-Marie,Loudet, Aurore,Differding, Edmond,Damien, Jean-Marie,Rémion, Jeanine,Van Uytbergen, Jacqueline,Ghosez, Léon
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p. 420 - 430
(2015/12/31)
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- Acyl iodides in organic synthesis: V. Reactions with carboxylic acid esters
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Acyl iodides react with alkyl, alkenyl, and aralkyl esters derived from saturated, unsaturated, and aromatic mono- and dicarboxylic acids in the absence of a catalyst. The reaction involves cleavage of the OR bond and formation of organic iodide RI (including CH2=CHI) and one or two symmetric carboxylic acid anhydrides. Phenyl acetate reacts with benzoyl iodide to give acetyl iodide and phenyl benzoate as a result of cleavage of the (O=)C-O bond. The reaction of diethyl fumarate with acetyl iodide is accompanied by cis- trans isomerization to afford maleic anhydride. In the reactions of acetyl iodide with diethyl oxalate and diethyl malonate, CO and CO2 and CO 2 and polyketene are formed, respectively, in addition to ethyl iodide and acetic anhydride. Ethyl esters of strong organic acids, e.g., ethyl trihaloacetates, failed to react with acyl iodides under analogous conditions.
- Voronkov,Trukhina,Vlasova
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p. 357 - 359
(2007/10/03)
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- Diiodosilane. 3. Direct Synthesis of Acyl Iodides from Carboxylic Acids, Esters, Lactones, Acyl Chlorides, and Anhydrides
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Diiodosilane (SiH2I2, DIS) is a very useful reagent for direct, high yield synthesis of acyl iodides from variety of carboxylic acid derivatives, such as carboxylic acids, esters, lactones, anhydrides, and acyl chlorides.These transformations are remarkably accelerated by iodine.In the absence of iodine DIS reacts with carboxylic acids and esters, much as does iodotrimethylsilane (TMSI), to form the corresponding silyl carboxylates.However, in contrast to TMSI, DIS and iodine react further with silyl carboxylates to produce acyl iodides.This reaction, when followed by addition of an appropriate alcohol, represents an esterification and transesterification method that is useful even for sterically hindered and/or poorly nucleophilic alcohols.Lactones react with DIS to produce either silyl ω-iodo carboxylates or ω-iodoacyl iodides, depending on the reaction conditions.The reaction between DIS and 1 equiv of a carboxylic anhydride affords, in the presence of iodine, 2 equiv of acyl iodide.
- Keinan, E.,Sahai, M.
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p. 3922 - 3926
(2007/10/02)
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- Formation of carboxylic acid halides by the reactions of halogens with acetyl-, (phenylacetyl)-, and benzoylchlorobis(triphenylphosphine)platinum(II) and acetyl-, (phenylacetyl)-, and benzoylchloro(triphenylphosphine)palladium(II) complexes
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The reactions of the acylmetal complexes trans-[M(PPh3)2Cl(RCO)] where M is Pt or Pd and R is CH3, C6H5CH2, or C6H5 with the halogens (X2) chlorine, bromine
- Kubota, Mitsuru,Boegeman, Scott C.,Keil, Robert N.,Webb, Carl G.
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p. 1616 - 1620
(2008/10/08)
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- Novel basic Ligands for the Homogeneous Catalytic Carbonylation of Methanol, XVI. - (Ether-Phosphane)-Rhodium Complexes as Model Compounds in the Carbonylation of Methanol
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The cationic complexes (4a, b) are obtained from 2 (1), AgSbF6/THF, and the (etherphosphane) ligands 3a, b via (2).In 4a, b COD is easily displaced by CO formation of (5a, b).When a THF solution of 5a, b is flushed with argon, only 5b eliminates carbon monoxide; in the resulting complex (7b) a Rh-O bond is present.The reaction is reversible.With rapid methyl migration via the non-detectable intermediates 9a, b and 8a, b oxidative addition of CH3I to 5a and 7b, respectively, affords the acyl complexes (6a, b) containing two Rh-O bonds.Heating of 6b in the presence of CO results in the reductive elimination of CH3C(O)I which upon hydrolysis is transformed to CH3CO2H.With cleavage of both Rh-O bonds back reaction occurs to give 5b.The formation of the individual complexes within the reaction cycle is promoted by the opening and closing mechanism of the (ether-phosphane) ligands 3a, b.
- Lindner, Ekkehard,Andres, Berthold
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p. 829 - 832
(2007/10/02)
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- Carbon-Halogen Bonding Studies. Halogen Redistribution Reactions between Alkyl or Acetyl Halides and Tri-n-butyltin Halides
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The equilibrium positions have been determined for the halogen redistribution reactions of tri-n-butyltin halides with a variety of structurally different types of alkyl halides and with acetyl halides.These have been related through the reaction ΔGo values to carbon-halogen bond dissociation energy differences.It is suggested that the trends observed in the latter may provide evidence for the existence of a small steric bond weakening effect in the order C-I > C-Br > C-Cl bonds on going from methyl to primary, secondary, and tertiary alkyl halides.On the other hand, with the 2,3-? bond containing allyl, benzyl, and propargyl halides , α-haloacetones, and haloacetonitriles, there may be some type of electronic carbon-halogen bond strengthening effect which lies in order C-I > C-Br > C-Cl.Finally, for the acetyl halides, the data are in agreement with increases in bond strengths resulting from ? contributions being in the order C-Cl > C-Br > C-I.
- Friedrich, Edwin C.,Abma, Charles B.
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p. 1367 - 1371
(2007/10/02)
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- 2-Acyl-3-substituted cyclopentan-1-ones and process for their preparation
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1,3-Dicarbonyl compounds useful as medicines, agricultural chemicals, perfumes, and their intermediates are prepared by reacting a specific α,β-unsaturated carbonyl compound with a specific organic copper lithium compound in the presence of an aprotic inert organic solvent, and then reacting the reaction product with an organic carboxylic acid halide or anhydride. In particular, novel 2-acyl-3-substituted cyclopentan-1-ones and 2-acyl-3-substituted cyclohexan-1-ones having important physiological activities are provided.
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- Optical brightening agents of naphthalimide derivatives
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A naphthalimide derivative having the formula STR1 wherein R is an alkyl, or cycloalkyl, an aralkyl, a haloalkyl, an alkoxyalkyl, a hydroxyalkyl, an N,N-dialkylaminoalkyl, an unsubstituted or halogen-, alkyl-, alkoxy- or hydroxy-substituted aryl, or an ammoniumalkyl; X is a group of the formula, STR2 wherein A is STR3 or an unsubstituted or halogen-substituted arylene, or a group of the formula, STR4 wherein R1 is hydrogen, an alkyl, phenyl, a hydroxyalkyl, or an alkoxyalkyl; Y is --CO--, --COO--, --CONR3 -- (where R3 is hydrogen or an alkyl), or --SO2 --; R2 is hydrogen, an alkyl, a cycloalkyl, an aralkyl, a haloalkyl, an alkyl- or aryl-substituted amino-alkyl, an unsubstituted or halogen-, alkyl-, alkoxy-, hydroxy-, amino- or alkylamino-substituted aryl, a group of the formula, STR5 (where R, R1 and Y are as defined above and R4 is a bivalent group), or a group of the formula, (where R5 is direct linkage or a bivalent group; Q+ is a substituted ammonium, a cycloammonium or a hydrazinium; and α- is an anion), Which is useful for optically brightening an organic polymer material.
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