774-65-2Relevant academic research and scientific papers
Silver(I)-carbene complexes/ionic liquids: Novel N-heterocyclic carbene delivery agents for organocatalytic transformations
Sentman, Alan C.,Csihony, Szilard,Waymouth, Robert M.,Hedrick, James L.
, p. 2391 - 2393 (2005)
(Chemical Equation Presented) N-Heterocyclic carbene (NHC) complexes with silver were investigated as sources of unsaturated NHC carbene catalysts via thermal decomposition. The NHC complex (1-ethyl-3-methylimidazol-2-ylidene) silver(I) chloride is an ionic liquid, and was found to catalyze the ring-opening polymerization of lactide at elevated temperatures to give narrowly dispersed polylactide of predictable molecular weight. Silver-carbene complexes can also be used for the catalysis of small molecule transesterification reactions. Thermolysis of the silver complexes in the presence of CS2 yielded the zwitter-ionic CS2 adducts of the carbene, implicating the intermediacy of the free carbene in these reactions.
Synthesis, characterization, and catalytic properties of SiPW-X mesoporous silica with heteropolyacid encapsulated into their framework
Shi, Chunfeng,Wang, Runwei,Zhu, Guangshan,Qiu, Shilun,Long, Jun
, p. 4801 - 4807 (2005)
A series of SiPW-X mesoporous silica with Keggin-type heteropolyacids (HPAs) encapsulated into their framework have been synthesized under strong acidic conditions. During hydrolysis of tetraethyl orthosilicate (TEOS), Na 2HPO4 (P source) and Na2WO4 (W Source) are added into the initial sol-gel system to form Keggin type HPAs. The final products have been intensively characterized by various techniques, such as XRD, TEM, N2 adsorption isotherm analysis, and by IR, UV/Visible, and 31P Magic Angle Spinning (MAS) NMR spectroscopy. Characterization results suggest that samples with an HPA weight percent of 13.3-20.7 % show very ordered hexagonal mesostructures. In addition, HPAs incorporated in the mesosilica are insoluble during catalysis. Results of catalytic tests show that SiPW-X materials have catalytic activities that are comparable to bulk HPA in catalytic tests implementing chemical reactions of both small (cumene cracking and esterification of ethanol with acetic acid) and bulky (1,3,5- triisopropylbenzene cracking and esterification of benzoic acid with tert-butanol) molecules. It can be readily separated from the reaction system for reuse, which suggests the potential industrial application. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
A one-pot and two-stage Baeyer-Villiger reaction using 2,2′-diperoxyphenic acid under biomolecule-compatible conditions?
Gan, Shaoyan,Shi, Lei,Song, Lijuan,Yin, Jingru,Yu, Zhiyou
supporting information, p. 2232 - 2239 (2022/04/03)
An efficient oxidant named 2,2′-diperoxyphenic acid was newly developed, and it exhibited high stability as revealed by thermogravimetric analysis (TGA) coupled with differential scanning calorimetry (DSC). On applying this reagent in the Baeyer-Villiger oxidation, the reaction featured a markedly broad substrate scope and good functional group tolerance, giving rise to the corresponding products in good to excellent yields. Particularly, in the case of pure water or 1× Phosphate Buffered Saline (1× PBS) serving as the solvent, the protocol could work well, resulting in yields ranging from 81% to 98%. Moreover, the catalytic asymmetric version of the BV reaction was explored as well, affording the corresponding products in good yields and medium ee. Remarkably, the corresponding biological compatibility and greenness assessment indicated that this reagent had favorable application prospects in the biomedical and green manufacturing fields. Meanwhile, mechanistic studies including 18O isotope effect experiments and DFT computations suggested that this reaction followed the generally accepted mechanism of BV oxidation.
Alkali-modified heterogeneous Pd-catalyzed synthesis of acids, amides and esters from aryl halides using formic acid as the CO precursor
Fapojuwo, Dele Peter,Maqunga, Nomathamsanqa Prudence,Meijboom, Reinout,Mogudi, Batsile M.,Molokoane, Pule Petrus,Onisuru, Oluwatayo Racheal,Oseghale, Charles O.
, p. 26937 - 26948 (2021/08/17)
To establish an environmentally friendly green chemical process, we minimized and resolved a significant proportion of waste and hazards associated with conventional organic acids and molecular gases, such as carbon monoxide (CO). Herein, we report a facile and milder reaction procedure, using low temperatures/pressures and shorter reaction time for the carboxyl- and carbonylation of diverse arrays of aryl halides over a newly developed cationic Lewis-acid promoted Pd/Co3O4catalyst. Furthermore, the reaction proceeded in the absence of acid co-catalysts, and anhydrides for CO release. Catalyst reusability was achievedviascalable, safer, and practical reactions that provided moderate to high yields, paving the way for developing a novel environmentally benign method for synthesizing carboxylic acids, amides, and esters.
Oxidative esterification of alcohols by a single-side organically decorated Anderson-type chrome-based catalyst
Wang, Jingjing,Jiang, Feng,Tao, Chaofu,Yu, Han,Ruhlmann, Laurent,Wei, Yongge
supporting information, p. 2652 - 2657 (2021/04/21)
The direct esterification of alcohols with non-noble metal-based catalytic systems faces great challenges. Here, we report a new chrome-based catalyst stabilized by a single pentaerythritol decorated Anderson-type polyoxometalate, [N(C4H9)4]3[CrMo6O18(OH)3C{(OCH2)3CH2OH}], which can realize the efficient transformation from alcohols to esters by H2O2oxidation in good yields and high selectivity without extra organic ligands. A variety of alcohols with different functionalities including some natural products and pharmaceutical intermediates are tolerated in this system. The chrome-based catalyst can be recycled several times and still keep the original configuration and catalytic activity. We also propose a reasonable catalytic mechanism and prove the potential for industrial applications.
Direct Amidation of Esters by Ball Milling**
Barreteau, Fabien,Battilocchio, Claudio,Browne, Duncan L.,Godineau, Edouard,Leitch, Jamie A.,Nicholson, William I.,Payne, Riley,Priestley, Ian
supporting information, p. 21868 - 21874 (2021/09/02)
The direct mechanochemical amidation of esters by ball milling is described. The operationally simple procedure requires an ester, an amine, and substoichiometric KOtBu and was used to prepare a large and diverse library of 78 amide structures with modest to excellent efficiency. Heteroaromatic and heterocyclic components are specifically shown to be amenable to this mechanochemical protocol. This direct synthesis platform has been applied to the synthesis of active pharmaceutical ingredients (APIs) and agrochemicals as well as the gram-scale synthesis of an active pharmaceutical, all in the absence of a reaction solvent.
Gram-Scale Preparation of Acyl Fluorides and Their Reactions with Hindered Nucleophiles
Barbasiewicz, Micha?,Tryniszewski, Micha?
, (2021/11/30)
A series of acyl fluorides was synthesized at 100 mmol scale using phase-transfer-catalyzed halogen exchange between acyl chlorides and aqueous bifluoride solution. The convenient procedure consists of vigorous stirring of the biphasic mixture at room temperature, followed by extraction and distillation. Isolated acyl fluorides (usually 7-20 g) display excellent purity and can be transformed into sterically hindered amides and esters when treated with lithium amide bases and alkoxides under mild conditions.
N-Aroylbenzotriazoles as Efficient Reagents for o-Aroylation in Absence of Organic Solvent
Hahnvajanawong, Viwat,Phungpis, Baramee
, p. 2671 - 2674 (2021/10/25)
N-Aroylbenzotriazoles have been shown to be efficient reagents for esterification in the absence of organic solvent. Grinding of N-aroylbenzoytiazoles with twofold excess of alcohols for a couple of hours at room temperature gave corresponding esters in high percentage of yields.
Enolate-Based Regioselective Anti-Beckmann C-C Bond Cleavage of Ketones
Jahn, Ullrich,Ma?ek, Tomá?
, p. 11608 - 11632 (2021/09/02)
The Baeyer-Villiger or Beckmann rearrangements are established methods for the cleavage of ketone derivatives under acidic conditions, proceeding for unsymmetrical precursors selectively at the more substituted site. However, the fragmentation regioselectivity cannot be switched and fragmentation at the less-substituted terminus is so far not possible. We report here that the reaction of ketone enolates with commercial alkyl nitrites provides a direct and regioselective way of fragmenting ketones into esters and oximes or ω-hydroxyimino esters, respectively. A comprehensive study of the scope of this reaction with respect to ketone classes and alkyl nitrites is presented. Control over the site of cleavage is gained through regioselective enolate formation by various bases. Oxidation of kinetic enolates of unsymmetrical ketones leads to the otherwise unavailable "anti-Beckmann"cleavage at the less-substituted side chain, while cleavage of thermodynamic enolates of the same ketones represents an alternative to the Baeyer-Villiger oxidation or the Beckmann rearrangement under basic conditions. The method is suited for the transformation of natural products and enables access to orthogonally reactive dicarbonyl compounds.
Metal nitrate-catalyzed one-pot oxidative esterification of benzaldehyde with hydrogen peroxide in alcoholic solutions at room temperature
Da Silva, Márcio José,De Oliveira, Cesar Macedo
, p. 3683 - 3691 (2021/03/03)
The activity of metal nitrate catalysts was investigated in the oxidative esterification reactions of benzaldehyde with hydrogen peroxide. Several types of metal nitrates (alkaline, alkaline earth, and transition metals) were evaluated as catalysts. Among the assessed salts, Fe(NO3)3 was the most efficient catalyst toward the formation of the target product (i.e., benzoic alkyl ester). In methyl alcohol, benzaldehyde was selectively oxidized to benzoic acid and then esterified to methyl benzoate. The efficiency of the catalyst was correlated with its higher Lewis acidity character, which was established through the pH measurements of methanolic solutions of the soluble metal nitrate salts. The influence of main variables of the reaction, such as catalyst load, temperature, and reactant stoichiometry, was investigated. The size of the carbon chain and steric hindrance played an essential role in the reaction selectivity. While methyl and ethyl alcohols selectively provided ester as the main product (ca. 70-75%) and acetal as the subproduct, the other alcohols gave ester, hemiacetal, and benzoic acid, which was formed in the least amount. The use of an inexpensive catalyst, a green oxidant, mild conditions, and short reaction times were the positive aspects of this one-pot process. The high TON (ca. 900) is evidence of the high catalytic activity of Fe(NO3)3. It is noteworthy that this methodology does not rely upon ligands and other additives.
