2548-87-0Relevant articles and documents
Pt-Catalyzed selective oxidation of alcohols to aldehydes with hydrogen peroxide using continuous flow reactors
Kon, Yoshihiro,Nakashima, Takuya,Yada, Akira,Fujitani, Tadahiro,Onozawa, Shun-Ya,Kobayashi, Shū,Sato, Kazuhiko
supporting information, p. 1115 - 1121 (2021/02/16)
The oxidation of alcohols to aldehydes is a powerful reaction pathway for obtaining valuable fine chemicals used in pharmaceuticals and biologically active compounds. Although many oxidants can oxidize alcohols, only a few hydrogen peroxide oxidations can be employed to continuously synthesize aldehydes in high yields using a liquid-liquid two-phase flow reactor, despite the possibility of the application toward a safe and rapid multi-step synthesis. We herein report the continuous flow synthesis of (E)-cinnamaldehyde from (E)-cinnamyl alcohol in 95%-98% yields with 99% selectivity for over 5 days by the selective oxidation of hydrogen peroxide using a catalyst column in which Pt is dispersed in SiO2. The active species for the developed selective oxidation is found to be zero-valent Pt(0) from the X-ray photoelectron spectroscopy measurements of the Pt surface before and after the oxidation. Using Pt black diluted with SiO2as a catalyst to retain the Pt(0) species with the optimal substrate and H2O2introduction rate not only enhances the catalytic activity but also maintains the activity during the flow reaction. Optimizing the contact time of the substrate with Pt and H2O2using a flow reactor is important to proceed with the selective oxidation to prevent the catalytic H2O2decomposition.
Radical induced disproportionation of alcohols assisted by iodide under acidic conditions
Huang, Yang,Jiang, Haiwei,Li, Teng,Peng, Yang,Rong, Nianxin,Shi, Hexian,Yang, Weiran
supporting information, p. 8108 - 8115 (2021/10/29)
The disproportionation of alcohols without an additional reductant and oxidant to simultaneously form alkanes and aldehydes/ketones represents an atom-economical transformation. However, only limited methodologies have been reported, and they suffer from a narrow substrate scope or harsh reaction conditions. Herein, we report that alcohol disproportionation can proceed with high efficiency catalyzed by iodide under acidic conditions. This method exhibits high functional group tolerance including aryl alcohol derivatives with both electron-withdrawing and electron-donating groups, furan ring alcohol derivatives, allyl alcohol derivatives, and dihydric alcohols. Under the optimized reaction conditions, a 49% yield of 5-methyl furfural and a 49% yield of 2,5-diformylfuran were obtained simultaneously from 5-hydroxymethylfurfural. An initial mechanistic study suggested that the hydrogen transfer during this redox disproportionation occurred through the inter-transformation of HI and I2. Radical intermediates were involved during this reaction.
Iodine-catalyzed alcohol disproportionation method
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Paragraph 0034-0035, (2021/06/13)
The invention relates to the technical field of catalysis, in particular to an iodine-catalyzed alcohol disproportionation method which comprises the following steps: sequentially adding alcohol, iodine and a solvent into a high-temperature and high-pressure reaction kettle, introducing a certain amount of nitrogen, conducting reacting for a certain time, collecting an organic phase after the reaction is ended, and conducting fractionating to obtain corresponding alkane and aldehyde/ketone. Alcohol disproportionation is efficient and atom-economical conversion without any additional oxidizing agent and reducing agent, and hydrocarbon and aldehyde/ketone molecules which are easy to separate can be formed at the same time. Meanwhile, the method has wide functional group tolerance, various substrate samples including aryl alcohol derivatives, heterocyclic alcohol derivatives, allyl alcohol derivatives and dihydric alcohol are tested, and the result shows that most of the substrate samples show good or extremely good yield.
Ligand coordination sphere effect of Schiff base cis-dioxomolybdenum(VI) complexes in selective catalytic oxidation of alcohols
Liu, Haiwen,Zhuo, Zihan,Zhang, Yan,Wei, Hang,Zhang, Wenxin,Li, Tong,Mao, Zuodong,Wang, Weili
, p. 1253 - 1261 (2021/08/13)
Several cis-dioxomolybdenum(VI) complexes with Schiff bases-derived ligands were synthesized and fully characterized. The catalytic performances of these complexes were tested in the alcohol oxidation under solvent-free condition using H2O2 as oxidant giving high results. The influence of the oxygen, sulfur, and nitrogen atom within the coordination sphere around the molybdenum center was studied (S?>?N?>?O). From this study, we suggest that there exists a relationship between the electronegativity of the atom and the catalytic performance in alcohol oxidation.
Rhodium-Catalyzed Regioselective Hydroformylation of Alkynes to α,β-Unsaturated Aldehydes Using Formic Acid
Fan, Chao,Hou, Jing,Chen, Yu-Jia,Ding, Kui-Ling,Zhou, Qi-Lin
supporting information, p. 2074 - 2077 (2021/04/05)
A rhodium-catalyzed hydroformylation of alkynes with formic acid was developed. The method provides α,β-unsaturated aldehydes in high yield and E-selectivity without the need to handle toxic CO gas.
Palladium/Copper-catalyzed Oxidation of Aliphatic Terminal Alkenes to Aldehydes Assisted by p-Benzoquinone
Komori, Saki,Yamaguchi, Yoshiko,Murakami, Yuka,Kataoka, Yasutaka,Ura, Yasuyuki
, p. 3946 - 3955 (2020/07/06)
The development of an anti-Markovnikov Wacker-type oxidation for simple aliphatic alkenes is a significant challenge. Herein, a variety of aldehydes can be selectively obtained from various unbiased aliphatic terminal alkenes using PdCl2(MeCN)2/CuCl in the presence of p-benzoquinone (BQ) under mild reaction conditions. Isomerization of the terminal alkene to the internal alkene was suppressed via slow addition of the starting material to the reaction mixture. In addition to the Pd catalyst, CuCl and BQ were essential in order to obtain the anti-Markovnikov product with high selectivity. Terminal alkenes bearing a halogen substituent afforded their corresponding aldehydes with high anti-Markovnikov selectivity. The halogen acts as a directing group in the reaction. DFT calculations indicate that a μ-chloro Pd(II)?Cu(I) bimetallic species with BQ coordinated to Cu is the catalytically active species in the case of a terminal alkene without a directing group.
Highly γ-Regioselective 1,2-Addition of α,β-Unsaturated Oxime Ethers with Allylzinc Bromides: A Straightforward Approach for the Synthesis of Homoallylic Amines
Yang, Bo,Zhang, Songlin
supporting information, p. 3736 - 3746 (2019/09/30)
A highly regioselective reaction between allylzinc bromide reagents and α,β-unsaturated oxime ethers for the one-step synthesis of the homoallylic amines is reported. This process is a regioselective 1,2-addition reaction providing a new γ-position with carbon-carbon bond formation. Furthermore, the reaction substrates are widely applicable and can be produced in a high yield.
Stereoselective Synthesis of C1–C7 and C6–C22 Fragments of Phostriecin, Goniothalamines, and Their Analogues
Purushotham Reddy,Vasudeva Reddy,Sabitha, Gowravaram
, p. 4389 - 4399 (2018/09/11)
The stereoselective synthesis of two fragments (C1–C7 and C6–C22) of the anti-tumor agent phostriecin has been achieved. The chiral hydroxy-vinyl-δ-lactone building block (fragment C1–C7) was subsequently utilized for the synthesis of 5-hydroxygoniothalamin, 5-acetoxygoniothalamin, and their derivatives.
Selective Aerobic Oxidation of Alcohols with NO3? Activated Nitroxyl Radical/Manganese Catalyst System
Lagerblom, Kalle,Keskiv?li, Juha,Parviainen, Arno,Mannisto, Jere,Repo, Timo
, p. 2908 - 2914 (2018/05/03)
A homogeneous Mn(NO3)2/2,2,6,6-tetramethylpiperidin-1-yl)oxyl/2-picolinic acid catalyst system is highly active and versatile for the selective aerobic oxidation of alcohols (2,2,6,6-tetramethylpiperidin-1-yl)oxyl=TEMPO, 2-picolinic acid=PyCOOH). The catalytic method enables near quantitative conversion of various primary alcohols to the respective aldehydes using a very simple reaction setup and workup. This study presents findings on the catalyst stability and mechanisms of deactivation. The results show that NO3? plays a crucial catalytic role in the reaction as a source of oxygen activating NOx species. Yet, disproportionation of NO3? to the volatile NO2 during the reaction leads to catalyst deactivation under open air conditions. Catalyst deactivation through this route can be overcome by adding a catalytic amount of nitrate salt, for example NaNO3 into the reaction. This stabilizes the Mn(NO3)2/TEMPO/PyCOOH catalyst and enables oxidation of various primary alcohols to the respective aldehydes using low catalyst loadings under ambient conditions. Secondary alcohols can be oxidized with a modified catalyst utilizing sterically accessible nitroxyl radical 9-azabicyclo[3.3.1]nonane N-oxyl (ABNO) instead of TEMPO. At the end of the alcohol oxidation, pure carbonyl products and the reusable catalyst can be recovered simply by extracting with organic solvent and dilute aqueous acid, followed by evaporation of both phases.
On the Use of Polyelectrolytes and Polymediators in Organic Electrosynthesis
Schille, Benjamin,Giltzau, Niels Ole,Francke, Robert
supporting information, p. 422 - 426 (2018/02/21)
Although organic electrosynthesis is generally considered to be a green method, the necessity for excess amounts of supporting electrolyte constitutes a severe drawback. Furthermore, the employment of redox mediators results in an additional separation problem. In this context, we have explored the applicability of soluble polyelectrolytes and polymediators with the TEMPO-mediated transformation of alcohols into carbonyl compounds as a test reaction. Catalyst benchmarking based on cyclic voltammetry studies indicated that the redox-active polymer can compete with molecularly defined TEMPO species. Alcohol oxidation was also highly efficient on a preparative scale, and our polymer-based approach allowed for the separation of both mediator and supporting electrolyte in a single membrane filtration step. Moreover, we have shown that both components can be reused multiple times.
