823-22-3Relevant articles and documents
Efficient hydrogenation of levulinic acid catalysed by spherical NHC-Ir assemblies with atmospheric pressure of hydrogen
Liu, Yaoqi,Lu, Zeye,Shen, Lingyun,Tu, Tao,Wu, Jiajie,Zheng, Qingshu
supporting information, p. 5037 - 5042 (2021/07/29)
A practical, efficient, and mild hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) under 1 atm H2was realized by single-sited 3D porous self-supported N-heterocyclic carbene iridium catalysts. Quantitative yields and selectivities were achieved at 0.02 mol% catalyst loading, and the catalyst could be reused for 9 runs without obvious loss of selectivity or activity.
STRONGLY LEWIS ACIDIC METAL-ORGANIC FRAMEWORKS FOR CONTINUOUS FLOW CATALYSIS
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Paragraph 0230-0232; 0236; 0239; 0259, (2021/02/26)
Lewis acidic metal-organic framework (MOF) materials comprising triflate-coordinated metal nodes are described. The materials can be used as heterogenous catalysts in a wide range of organic group transformations, including Diels-Alder reactions, epoxide-ring opening reactions, Friedel-Crafts acylation reactions and alkene hydroalkoxylation reactions. The MOFs can also be prepared with metallated organic bridging ligands to provide heterogenous catalysts for tandem reactions and/or prepared as composites with support particles for use in columns of continuous flow reactor systems. Methods of preparing and using the MOF materials and their composites are also described.
Preparation method of delta-caprolactone
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Paragraph 0077; 0083; 0085-0086; 0088, (2021/08/25)
The invention relates to a preparation method of delta-caprolactone. The method comprises the following steps: dissolving a beta-dicarbonyl compound and a basic catalyst in a solvent, and conducting preheating; dropwise adding alkyl acrylate into a reaction system for a Michael addition reaction; cooling the system, adding alkali, and then heating the reaction system for saponification reaction; adding water, cooling the system, and adding a reducing agent for reaction; and cooling the system, adjusting the pH value with acid, and carrying out post-treatment to obtain the delta-caprolactone. The method disclosed by the invention is simple in process operation, high in safety, high in raw material utilization rate, short in total consumed time and free of generation of carbon dioxide.
Synthesis method of delta-caprolactone spice
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Paragraph 0016; 0023; 0027-0028; 0032-0033; 0037-0038; 0042, (2021/02/06)
The invention discloses a synthesis method of delta-caprolactone spice, which comprises the following steps of by taking ethyl acetoacetate and methyl acrylate as initial raw materials, adding an alkaline substance with the mass fraction of 0.1-1%, controlling the temperature to be 30-100 DEG C, reacting for 1-8 hours, reacting to obtain acetyl succinate, stirring, heating and washing an acidic substance and acetyl succinate to obtainacetobutyric acid, adding the acetylbutyric acid and hydrogen into a hydrogenation kettle, and performing hydrogenation under the conditions that the temperatureis 60-120 DEG C and the pressure intensity is 0.4-1.2 MPa to obtain delta-caprolactone. The method is simple in process step, high in yield, free of side reaction and simple to separate from impurities, and delta-caprolactone is an important organic compound and an intermediate; the method has a wide application and development prospect in the field of synthesis of essences, fragrances and medicines, and natural products exist in coconut oil, hot milk fat and the like and are widely applied to edible essences and tobacco essences.
Photo-induced radical borylation of hemiacetals via C–C bond cleavage
Liu, Qianyi,Zhang, Jianning,Zhang, Lei,Mo, Fanyang
supporting information, (2021/01/05)
In this study, we reported a photo-induced radical borylation of hemiacetal derivatives via C–C bond cleavage. This transformation can be realized under mild conditions with simple reaction settings and irradiation of visible light. A series of substrates, including both cyclic and linear hemiacetal derivatives, were effectively transformed to the borylation product in moderate to good yields. Finally, the mechanism was studied in detail by DFT calculations, suggesting insight of the radical borylation process.
(Cyclopentadienone)iron-Catalyzed Transfer Dehydrogenation of Symmetrical and Unsymmetrical Diols to Lactones
Tang, Yidan,Meador, Rowan I. L.,Malinchak, Casina T.,Harrison, Emily E.,McCaskey, Kimberly A.,Hempel, Melanie C.,Funk, Timothy W.
, p. 1823 - 1834 (2020/02/04)
Air-stable iron carbonyl compounds bearing cyclopentadienone ligands with varying substitution were explored as catalysts in dehydrogenative diol lactonization reactions using acetone as both the solvent and hydrogen acceptor. Two catalysts with trimethylsilyl groups in the 2- A nd 5-positions, [2,5-(SiMe3)2-3,4-(CH2)4(δ4-C4C= O)]Fe(CO)3 (1) and [2,5-(SiMe3)2-3,4-(CH2)3(δ4-C4C= O)]Fe(CO)3 (2), were found to be the most active, with 2 being the most selective in the lactonization of diols containing both primary and secondary alcohols. Lactones containing five-, six-, and seven-membered rings were successfully synthesized, and no over-oxidations to carboxylic acids were detected. The lactonization of unsymmetrical diols containing two primary alcohols occurred with catalyst 1, but selectivity was low based on alcohol electronics and modest based on alcohol sterics. Evidence for a transfer dehydrogenation mechanism was found, and insight into the origin of selectivity in the lactonization of 1°/2° diols was obtained. Additionally, spectroscopic evidence for a trimethylamine-ligated iron species formed in solution during the reaction was discovered.
Strongly Lewis Acidic Metal-Organic Frameworks for Continuous Flow Catalysis
Ji, Pengfei,Feng, Xuanyu,Oliveres, Pau,Li, Zhe,Murakami, Akiko,Wang, Cheng,Lin, Wenbin
supporting information, p. 14878 - 14888 (2019/10/02)
The synthesis of highly acidic metal-organic frameworks (MOFs) has attracted significant research interest in recent years. We report here the design of a strongly Lewis acidic MOF, ZrOTf-BTC, through two-step transformation of MOF-808 (Zr-BTC) secondary building units (SBUs). Zr-BTC was first treated with 1 M hydrochloric acid solution to afford ZrOH-BTC by replacing each bridging formate group with a pair of hydroxide and water groups. The resultant ZrOH-BTC was further treated with trimethylsilyl triflate (Me3SiOTf) to afford ZrOTf-BTC by taking advantage of the oxophilicity of the Me3Si group. Electron paramagnetic resonance spectra of Zr-bound superoxide and fluorescence spectra of Zr-bound N-methylacridone provided a quantitative measurement of Lewis acidity of ZrOTf-BTC with an energy splitting (?E) of 0.99 eV between the ?x? and ?y? orbitals, which is competitive to the homogeneous benchmark Sc(OTf)3. ZrOTf-BTC was shown to be a highly active solid Lewis acid catalyst for a broad range of important organic transformations under mild conditions, including Diels-Alder reaction, epoxide ring-opening reaction, Friedel-Crafts acylation, and alkene hydroalkoxylation reaction. The MOF catalyst outperformed Sc(OTf)3 in terms of both catalytic activity and catalyst lifetime. Moreover, we developed a ZrOTf-BTC?SiO2 composite as an efficient solid Lewis acid catalyst for continuous flow catalysis. The Zr centers in ZrOTf-BTC?SiO2 feature identical coordination environment to ZrOTf-BTC based on spectroscopic evidence. ZrOTf-BTC?SiO2 displayed exceptionally high turnover numbers (TONs) of 1700 for Diels-Alder reaction, 2700 for epoxide ring-opening reaction, and 326 for Friedel-Crafts acylation under flow conditions. We have thus created strongly Lewis acidic sites in MOFs via triflation and constructed the MOF?SiO2 composite for continuous flow catalysis of important organic transformations.
Calcium(II)- And Triflimide-Catalyzed Intramolecular Hydroacyloxylation of Unactivated Alkenes in Hexafluoroisopropanol
Qi, Chenxiao,Yang, Shengwen,Gandon, Vincent,Leb?uf, David
supporting information, p. 7405 - 7409 (2019/10/02)
We report an efficient intramolecular hydroacyloxylation of unactivated alkenes, offering a streamlined access to relevant γ-lactones, which features the utilization of either a calcium(II) salt or triflimide as a catalyst in hexafluoroisopropanol. This method could be applied to the synthesis of natural products and the late-stage functionalization of natural and bioactive molecules. Additionally, DFT computations were used to elucidate the twist of reactivity observed between the hydroamidation and hydroacyloxylation of unactivated alkenes regarding the formation of 5- and 6-membered rings.
W(OTf)6-Catalyzed Synthesis of Γ-Lactones by Ring Contraction of Macrolides or Ring Closing of Terminal Hydroxyfatty Acids in Ionic Liquid
Xie, Zhong-Yu,Deng, Jin,Fu, Yao
, p. 2332 - 2339 (2018/07/31)
γ-Lactones are an important class of fine chemical products and are widely used in perfumes, medicines, pesticides, dyes, and other fields. Herein, a new method for γ-lactones preparation based on ring contraction was developed. Starting from macrolides, W(OTf)6 was used to catalyze the ring-opening polymerization then depolymerization. The depolymerization step was not a common ring-closing process, and the carbon number of the ring was reduced one by one by rearrangement to form the most thermodynamically stable five-membered ring compounds. γ-Caprolactone (180 °C for 10 h) was obtained in a yield of 94 % when [EMIM]OTf was used as the solvent, and the yield of isolated product was up to 85 %. The interaction of various components and the reaction mechanism were studied by FTIR spectroscopy and 1H NMR spectroscopy, respectively. Furthermore, γ-lactones could be produced when the substrate was extended to terminal hydroxyfatty acids. Unexpectedly, the catalyst was poisoned by 1 equivalent of H2O added during the process and thus the yield decreased greatly. The reaction is green and simple, and proceeds in one pot with high atom economy (100 % for macrolides and with water as the only byproduct for terminal hydroxyfatty acid), which provides a promising approach to synthesizing γ-lactones.
Aldol condensation among acetaldehyde and ethanol reactants on TiO2: Experimental evidence for the kinetically relevant nucleophilic attack of enolates
Zhang, Hongbo,Ibrahim, Malek Y.S.,Flaherty, David W.
, p. 290 - 302 (2018/04/02)
Combinations of rate measurements as functions of reactant pressures, in situ infrared spectroscopy, comparisons of kinetic isotope effects, and rate inhibition effects provide experimental evidence that aldol condensation of acetaldehyde proceeds by kinetically relevant nucleophilic attack of a reactive enolate upon an acetaldehyde molecule over anatase TiO2. Steady-state turnover rates of aldol condensation measured as a function of the pressures of C2H4O, C2H5OH, H2O, and H2 between 503 K and 537 K show that rates reflect a second order dependence on C2H4O pressure and an inverse second order dependence on the C2H5OH pressure at the lowest C2H4O-to-C2H5OH ratios. Infrared spectra obtained in situ show that the exposed cationic Ti-atoms that facilitate aldol addition on TiO2 surfaces are saturated with C2H5OH? species and C2H4O? coverages are much smaller. In addition, aldol rates increase when C2D4O replaces C2H4O as a reactant, which likely reflects an inverse, secondary isotope effect caused by rehybridization of C-atoms at the transition state that forms a C–C bond between two reactive intermediates derived from acetaldehyde. These results suggest that the kinetically relevant step is a bimolecular surface reaction, specifically the nucleophilic attack of an enolate onto a vicinal C2H4O? species. This conclusion is consistent also with aldol condensation rates that decrease with an inverse second order dependence on pyridine (C5H5N) pressure, because C5H5N displaces C2H4O from the two Lewis acid sites involved in the kinetically relevant step (confirmed by in situ FTIR). Comparisons to recent reports on the mechanism of this reaction on anatase TiO2 indicate that the presence of high coverages of C2H5OH? causes nucleophilic attack to become the kinetically relevant step by significantly reducing the number of enolate-acetaldehyde reactant pairs upon the surface.
