947-91-1Relevant academic research and scientific papers
Diphenylacetaldehyde and Its Enol: Determination of the Keto-Enol and Hydration Equilibrium Constants and the pKa's of the Aldehyde, Enol, and Hydrate. Comparison with Sterically Hindered System
Chiang, Y.,Kresge, A.J.,Krogh, E.T.
, p. 2600 - 2607 (1988)
The enol isomer of diphenylacetaldehyde was generated in aqueous solution from its potassium salt, formed by treating the aldehyde, with potassium hydride, and rates of ketonization of this enol were measured at 25 deg C in perchloric acid and sodium hydroxide solutions and acetic acid and bicarbonate ion buffers.These data, coupled with rates of enolization of the aldehyde measured at 25 deg C in acetic acid buffer and sodium hydroxide solutions, lead to duplicate independent determinations of the keto-enol equilibrium constant, , , the acid dissociation constant of the enol ionizing as an oxygen acid, , , and the acid dissociation constant of the aldehyde ionizing as a carbon acid, , .The equilibrium constant for formation of the aldehyde hydrate, Kh=4.7+/-0.2, was also determined by two independent methods, and the acid dissociation constant of the hydrate ionizing as an oxygen acid, , , was evaluated from kinetic data.The unusually large values of KE and for this system are attributed to stabilization of the carbon-carbon double bonds of the enol and enolate ion by the phenyl substituents.Comparison with literature data on sterically hindered, stable, "Fuson" enols bearing mesityl substituents suggests that a substantial portion of the thermodynamic stability of Fuson enols is provided by similar phenyl group stabilization of their double bonds; the methyls of the mesityl substituents of Fuson enols, however, do appear to play a critical role in conferring kinetic stability upon these substances.
Pd(0)-catalyzed amphiphilic allylation of aldehydes with vinyl epoxide
Kimura, Masanari,Mukai, Ryutaro,Tamaki, Takato,Horino, Yoshikazu,Tamaru, Yoshinao
, p. 4122 - 4123 (2007)
Under Pd(0)-Et3B catalysis, vinyl epoxide serves as a formal 3-butenyl 2-anion-1-cation equivalent, and the cation reacts with aldehydes at the α-position, and the anion, at the carbonyl carbon, furnishing 2-vinylcyclobutanols in one pot. Copyright
Palladium-Catalyzed Allenamide Carbopalladation/Allylation with Active Methine Compounds
Zhu, Xiaoyi,Li, Ruibo,Yao, Hequan,Lin, Aijun
, p. 4630 - 4634 (2021/06/28)
A palladium-catalyzed allenamide carbopalladation/allylation with active methine compounds has been developed. Various indoles and isoquinolinones bearing a quaternary carbon center were achieved with good efficiency, a broad substrate scope and good functional group tolerance. This reaction underwent cascade oxidative addition, carbopalladation, and allylic alkylation, and two new C-C bonds were formed in one pot.
Competition Between Cα-S and Cα-Cβ Bond Cleavage in β-Hydroxysulfoxides Cation Radicals Generated by Photoinduced Electron Transfer?
Lapi, Andrea,D'Alfonso, Claudio,Del Giacco, Tiziana,Lanzalunga, Osvaldo
, p. 1310 - 1321 (2021/06/07)
A kinetic and product study of the 3-cyano-N-methyl-quinolinium photoinduced monoelectronic oxidation of a series of β-hydroxysulfoxides has been carried out to investigate the competition between Cα-S and Cα-Cβ bond cleavage within the corresponding cation radicals. Laser flash photolysis experiments unequivocally established the formation of sulfoxide cation radicals showing their absorption band (λmax ≈ 520?nm) and that of 3-CN-NMQ? (λmax ≈ 390?nm). Steady-state photolysis experiments suggest that, in contrast to what previously observed for alkyl phenyl sulfoxide cation radicals that exclusively undergo Cα-S bond cleavage, the presence of a β-hydroxy group makes, in some cases, the Cα-Cβ scission competitive. The factors governing this competition seem to depend on the relative stability of the fragments formed from the two bond scissions. Substitution of the β-OH group with -OMe did not dramatically change the reactivity pattern of the cation radicals thus suggesting that the observed favorable effect of the hydroxy group on the Cα-Cβ bond cleavage mainly resides on its capability to stabilize the carbocation formed upon this scission.
B(C6F5)3-catalyzed tandem protonation/deuteration and reduction of: In situ -formed enamines
Wu, Rongpei,Gao, Ke
supporting information, p. 4032 - 4036 (2021/05/19)
A highly efficient B(C6F5)3-catalyzed tandem protonation/deuteration and reduction of in situ-formed enamines in the presence of water and pinacolborane was developed. Regioselective β-deuteration of tertiary amines was achieved with high chemo- and regioselectivity. D2O was used as a readily available and cheap source of deuterium. Mechanistic studies indicated that B(C6F5)3 could activate water to promote the protonation and reduction of enamines. This journal is
A Bifunctional Iron Nanocomposite Catalyst for Efficient Oxidation of Alkenes to Ketones and 1,2-Diketones
Ma, Zhiming,Ren, Peng,Song, Tao,Xiao, Jianliang,Yang, Yong,Yuan, Youzhu
, p. 4617 - 4629 (2020/05/19)
We herein report the fabrication of a bifunctional iron nanocomposite catalyst, in which two catalytically active sites of Fe-Nx and Fe phosphate, as oxidation and Lewis acid sites, were simultaneously integrated into a hierarchical N,P-dual doped porous carbon. As a bifunctional catalyst, it exhibited high efficiency for direct oxidative cleavage of alkenes into ketones or their oxidation into 1,2-diketones with a broad substrate scope and high functional group tolerance using TBHP as the oxidant in water under mild reaction conditions. Furthermore, it could be easily recovered for successive recycling without appreciable loss of activity. Mechanistic studies disclose that the direct oxidation of alkenes proceeds via the formation of an epoxide as intermediate followed by either acid-catalyzed Meinwald rearrangement to give ketones with one carbon shorter or nucleophilic ring-opening to generate 1,2-diketones in a cascade manner. This study not only opens up a fancy pathway in the rational design of Fe-N-C catalysts but also offers a simple and efficient method for accessing industrially important ketones and 1,2-diketones from alkenes in a cost-effective and environmentally benign fashion.
Method for preparing substituted carbonyl compound by catalyzing pinacol rearrangement reaction through molecular sieve
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Paragraph 0015-0020, (2020/09/12)
The invention discloses a method for preparing a substituted carbonyl compound by catalyzing pinacol rearrangement reaction through a molecular sieve. The method is characterized in that substituted pinacol as a substrate and toluene as solvent are subjected to a rearrangement reaction for 2-5h under the catalysis of an MCM-41, SBA-15, USY, Beta ZSM-5 or other aluminum-containing H-type acidic molecular sieve, the reaction temperature is 80-110 DEG C, the mass ratio of the substituted pinacol to the toluene to the catalyst is 100: 100: (10-50), the catalyst is filtered out after the reaction is finished, and purifying is performed to obtain a product, namely, the substituted carbonyl compound. Compared with the prior art, the method provided by the invention has the advantages of wide substrate application range, cheap catalyst, easy preparation, stability, no pollution to the environment, recyclability, realization of gram-scale preparation, and high reaction yield.
Formal [3+2] cycloaddition reactions of electron-rich aryl epoxides with alkenes under Lewis acid catalysis affording tetrasubstituted tetrahydrofurans
Macías-Villamizar, Víctor E.,Cuca-Suárez, Luís,Rodríguez, Santiago,González, Florenci V.
supporting information, (2020/02/18)
We report on the regio- and stereoselective synthesis of tetrahydrofurans by reaction between epoxides and alkenes in the presence of a Lewis acid. This is an unprecedented formal [3+2] cycloaddition reaction between an epoxide and an alkene. The chemical reaction represents a very concise synthesis of tetrahydrofurans from accessible starting compounds.
Silica-supported orthophosphoric acid (OPA/SiO2): preparation, characterization, and evaluation as green reusable catalyst for pinacolic rearrangement
Billamboz, Muriel,Banaszak, Estelle
, p. 1029 - 1040 (2019/04/10)
In this paper, we report an easy-to-prepare, cost-effective, efficient, and reusable silica-supported orthophosphoric acid (OPA) catalyst for pinacolic rearrangement. The surface properties of this catalyst were successfully characterized with the help of 31P NMR, TGA, DSC, FT-IR, titration, and microscopy. OPA, hydrogen bonded on the surface, is actually the active species and the reaction seems to occur in the liquid phase embedded in the silica support. As a consequence, the extracting solvent should be chosen with cautious to guarantee the recyclability of the catalyst. As example, pinacol rearrangement reactions were successfully realized with this catalyst and OPA/SiO2 proved to be as efficient as homogeneous orthophosphoric acid to promote the reaction of pinacol derivatives. When using dichloromethane as extracting solvent, OPA/SiO2 can be reuse up to ten times without a significant loss of activity. After ten runs, no physical damage of the catalyst has been observed by microscopy proving its suitability for such application.
Epoxidation of Cyclooctene Using Water as the Oxygen Atom Source at Manganese Oxide Electrocatalysts
Jin, Kyoungsuk,Maalouf, Joseph H.,Lazouski, Nikifar,Corbin, Nathan,Yang, Dengtao,Manthiram, Karthish
supporting information, p. 6413 - 6418 (2019/05/02)
Epoxides are useful intermediates for the manufacture of a diverse set of chemical products. Current routes of olefin epoxidation either involve hazardous reagents or generate stoichiometric side products, leading to challenges in separation and significant waste streams. Here, we demonstrate a sustainable and safe route to epoxidize olefin substrates using water as the oxygen atom source at room temperature and ambient pressure. Manganese oxide nanoparticles (NPs) are shown to catalyze cyclooctene epoxidation with Faradaic efficiencies above 30%. Isotopic studies and detailed product analysis reveal an overall reaction in which water and cyclooctene are converted to cyclooctene oxide and hydrogen. Electrokinetic studies provide insights into the mechanism of olefin epoxidation, including an approximate first-order dependence on the substrate and water and a rate-determining step which involves the first electron transfer. We demonstrate that this new route can also achieve a cyclooctene conversion of ～50% over 4 h.
