586-76-5Relevant articles and documents
Selective conversion of aldehydes to carboxylic acids by hemoglobin and air
Hajimohammadi, Mahdi,Verjani, Maryam Khalaji,Ghasemi, Hoda,Safari, Nasser,Kn?r, Günther
, p. 679 - 685 (2018)
A new green, environmentally friendly and economically feasible method for the oxygenation of benzaldehyde, cinnamaldehyde, 4-chlorobenzaldehyde and 4-bromobenzaldehyde to the corresponding carboxylic acids using air in the presence of hemoglobin as a water-soluble catalyst in aqueous media at room temperature is illustrated. The resulting products were obtained with (77-100%) conversion and 100% selectivity within a reasonable amount of time. In addition, the first direct characterization of a high-valent iron intermediate (HbFeIV+ =O) measured using Mass Spectroscopy (MS) and UV-vis spectroscopy proved that the major route for oxidation of aldehydes is (HbFeIV+ =O) production.
Mesoporous silica-supported Pd catalysts: An investigation into structure, activity, leaching and heterogeneity
Webb, Jonathan D.,MacQuarrie, Stephanie,McEleney, Kevin,Crudden, Cathleen M.
, p. 97 - 109 (2007)
Mesoporous silica functionalized by mercaptopropyl trimethoxysilane can be loaded with palladium and the resulting material used as a catalyst for a variety of coupling reactions. The ordered silicate reacts with levels of Pd leaching in the low ppm to ppb range. The catalyst can be re-used multiple times with only moderate loss of activity or structure, depending on the method of incorporation of the thiol. A grafting approach gives a significantly more stable material which is likely insulated from attack by the aqueous base, while incorporation of the thiol by co-condensation gives a material with minimal stability under the reaction conditions. Several heterogeneity tests are performed on the catalyst including three-phase tests and poisoning studies. These indicate that the effective heterogeneity depends strongly on the solvent employed and the reaction conditions. Under non-aerobic conditions with a controlled ratio of sulfur ligand to palladium, low levels of reaction due to homogeneous species are observed, but as the organic content of the solvent is increased, more reaction on an immobilized reagent (as judged through the three-phase test) is observed. In addition, these studies highlight the constraints within which the three-phase test can be an accurate assessment of heterogeneity.
Formation, Oxidation, and Fate of the Breslow Intermediate in the N-Heterocyclic Carbene-Catalyzed Aerobic Oxidation of Aldehydes
Bortolini, Olga,Chiappe, Cinzia,Fogagnolo, Marco,Massi, Alessandro,Pomelli, Christian Silvio
, p. 302 - 312 (2017)
The reaction paths and intermediate structures related to the formation of the Breslow intermediate and its oxidation along the oxidative/oxygenative lanes have been studied from a mechanistic point of view, with the support of gas-phase and computational studies. The results confirm the occurrence of a single-electron transfer from the Breslow intermediate to the molecular oxygen with formation of a radical couple that recombines either as a peroxide anion 7′ to afford the aldehyde-to-carboxylic acid product or as a hydroperoxy derivative 7″ that evolved into an electrophilic acyl azolium, opening to the aldehyde-to-ester conversion. Steric factors enter into determining the different reactivity. All of the intermediates of both catalytic paths have been observed and characterized under mass spectrometric conditions. In particular, for the imidazoline catalyst, the (+)ESI-MS/(MS) detection of the genuine Breslow intermediate was made possible in virtue of its limited reactivity. Mechanistic aspects of the N-heterocyclic carbenes catalyzed aerobic oxidation of aldehydes shares important similarities with that one of the recently revisited benzoin condensation.
Experimental and theoretical studies of (4?+?1) annulations between α-oxoketenes and stable phosphorous, nitrogen, or sulfur ylides
Pierrot, David,Rajzmann, Michel,Carissan, Yannick,Rodriguez, Jean,Bonne, Damien,Coquerel, Yoann
, (2019)
α-Oxoketenes generated in situ by a microwave-assisted Wolff rearrangement at 170°C were found to react with stabilized sulfur ylides in (4?+?1) annulation processes to afford functionalized 3-hydroxyfurans. Theoretical mechanistic investigations revealed that the reaction proceeds in two steps via a short-lived betaine intermediate, a general feature of the reactions of α-oxoketenes with stable phosphorous, nitrogen, and sulfur ylides.
Palladium(II) complex of an organotellurium ligand as a catalyst for Suzuki Miyaura coupling: Generation and role of nano-sized Pd3Te 2
Rao, Gyandshwar Kumar,Kumar, Arun,Singh, Mahabir Pratap,Singh, Ajai K.
, p. 1 - 6 (2014)
Organotellurium ligand (L = (C6H5)(2-HOC 6H4)CHNH(CH2)3Te-C6H 4-4-OMe) and its palladium complex [PdCl(L-H)](1) have been synthesized and characterized by multinuclei NMR and mass spectra. The L coordinates with Pd(II) in a (N,Te,C-) mode. The complex 1 has been used to catalyze Suzuki-Miyaura coupling (SMC) reaction. The conversions at 0.1 mol% loading of the complex catalyst were good for coupling of phenylboronic acid with various aryl bromides. In case of 4-formylphenylboronic acid catalyst loading needed was higher. In the course of catalysis nanoparticles (NPs) were generated. They were isolated and characterized as Pd3Te2 species (～1-2 nm size). Catalytic activity of 1 has been ascribed via these NPs. A cocktail process involving both homogeneous and heterogeneous routes appears to carry out catalysis.
Synthesis, catalytic activity, and leaching studies of a heterogeneous Pd-catalyst including an immobilized bis(oxazoline) ligand
Gruber-Woelfler,Radaschitz,Feenstra,Haas,Khinast
, p. 30 - 40 (2012)
The synthesis and characterization of a novel catalytic system including Pd(OAc)2 attached to a bis(oxazoline) (=BOX) ligand that is covalently bonded to 3-mercaptopropyl-functionalized silica gel is presented. The catalyst was tested for Suzuki-Miyaura reactions of different aryl halides with phenylboronic acid. The heterogeneity of the catalytic system was investigated using different approaches, indicating that there is virtually no Pd leaching into the reaction solution under the applied reaction conditions. Furthermore, our results show that the catalytic system can be reused multiple times without significant loss of stability or structure.
ROMP-spheres: A novel high-loading polymer support using cross metathesis between vinyl polystyrene and norbornene derivatives
Barrett, Anthony G. M.,Cramp, Susan M.,Roberts, Richard S.
, p. 1083 - 1086 (1999)
(matrix presented) The preparation of a polymer-supported ruthenium alkylidene metathesis catalyst has described. This immobilized catalyst has been used to initiate a ring-opening metathesis polymerization of norbornene derivatives onto a polymer support to prepare novel high-loading resins for use in combinatorial chemistry.
Transformation of Thioacids into Carboxylic Acids via a Visible-Light-Promoted Atomic Substitution Process
Fu, Qiang,Liang, Fu-Shun,Lou, Da-Wei,Pan, Gao-Feng,Wang, Rui,Wu, Min,Xie, Kai-Jun
supporting information, p. 2020 - 2024 (2022/03/31)
A visible-light-promoted atomic substitution reaction for transforming thiocacids into carboxylic acids with dimethyl sulfoxide (DMSO) as the oxygen source has been developed, affording various alkyl and aryl carboxylic acids in over 90% yields. The atomic substitution process proceeds smoothly through the photochemical reactivity of the formed hydrogen-bonding adduct between thioacids and DMSO. A DMSO-involved proton-coupled electron transfer (PCET) and the simultaneous generation of thiyl and hydroxyl radicals are proposed to be key steps for realizing the transformation.
Cleavage of Carboxylic Esters by Aluminum and Iodine
Sang, Dayong,Yue, Huaxin,Fu, Yang,Tian, Juan
, p. 4254 - 4261 (2021/03/09)
A one-pot procedure for deprotecting carboxylic esters under nonhydrolytic conditions is described. Typical alkyl carboxylates are readily deblocked to the carboxylic acids by the action of aluminum powder and iodine in anhydrous acetonitrile. Cleavage of lactones affords the corresponding ω-iodoalkylcarboxylic acids. Aryl acetylates undergo deacetylation with the participation of the neighboring group. This method enables the selective cleavage of alkyl carboxylic esters in the presence of aryl esters.
Amide Bond Formation via Aerobic Photooxidative Coupling of Aldehydes with Amines Catalyzed by a Riboflavin Derivative
Hassan Tolba, Amal,Krupi?ka, Martin,Chudoba, Josef,Cibulka, Radek
supporting information, p. 6825 - 6830 (2021/09/11)
We report an effective, operationally simple, and environmentally friendly system for the synthesis of tertiary amides by the oxidative coupling of aromatic or aliphatic aldehydes with amines mediated by riboflavin tetraacetate (RFTA), an inexpensive organic photocatalyst, and visible light using oxygen as the sole oxidant. The method is based on the oxidative power of an excited flavin catalyst and the relatively low oxidation potential of the hemiaminal formed by amine to aldehyde addition.
