6688-11-5Relevant academic research and scientific papers
Kinetics of cyclooctene hydroformylation for continuous homogeneous catalysis
Gueven, Sabriye,Hamers, Bart,Franke, Robert,Priske, Markus,Becker, Marc,Vogt, Dieter
, p. 524 - 530 (2014)
The kinetics of Rh-catalysed cyclooctene hydroformylation were investigated, based on the mechanism described for a single tris(2,4-di-tert- butylphenyl)phosphite ligand coordinated to a rhodium center. The rate limiting step was found to be the coordination of cyclooctene to the metal center as suggested in literature. Parameters of the corresponding rate equation were estimated by nonlinear regression. Experimental data obtained from semi-batch reactions were compared with model predictions and shown to be in good agreement. A continuous jet-loop reactor with coupled nanofiltration was designed and the kinetics were validated. The Royal Society of Chemistry.
Methylene C(sp3)-H β,β′-Diarylation of Cyclohexanecarbaldehydes Promoted by a Transient Directing Group and Pyridone Ligand
Bull, James A.,St John-Campbell, Sahra,White, Andrew J. P.
supporting information, (2020/03/10)
A hindered β-amino amide transient directing group effects di-trans-arylation of cyclohexanecarbaldehydes. The amide N-substituents are shown to affect yield and can enhance the rate of arylation compared with the α-amino acid. Addition of a pyridone ligand further enhanced reactivity. The reaction is successful for a range of aryl iodides, and various substituted cyclohexane carboxaldehydes, providing functionalized products from simple feedstocks. A mechanism is proposed evoking a transient enamine.
Binuclear Pd(I)-Pd(I) Catalysis Assisted by Iodide Ligands for Selective Hydroformylation of Alkenes and Alkynes
Zhang, Yang,Torker, Sebastian,Sigrist, Michel,Bregovi?, Nikola,Dydio, Pawe?
supporting information, p. 18251 - 18265 (2020/11/02)
Since its discovery in 1938, hydroformylation has been thoroughly investigated and broadly applied in industry (>107 metric ton yearly). However, the ability to precisely control its regioselectivity with well-established Rh- or Co-catalysts has thus far proven elusive, thereby limiting access to many synthetically valuable aldehydes. Pd-catalysts represent an appealing alternative, yet their use remains sparse due to undesired side-processes. Here, we report a highly selective and exceptionally active catalyst system that is driven by a novel activation strategy and features a unique Pd(I)-Pd(I) mechanism, involving an iodide-assisted binuclear step to release the product. This method enables β-selective hydroformylation of a large range of alkenes and alkynes, including sensitive starting materials. Its utility is demonstrated in the synthesis of antiobesity drug Rimonabant and anti-HIV agent PNU-32945. In a broader context, the new mechanistic understanding enables the development of other carbonylation reactions of high importance to chemical industry.
Boosting the hydrolytic stability of phosphite ligand in hydroformylation by the construction of superhydrophobic porous framework
Tang, Yongquan,Dong, Ke,Wang, Sai,Sun, Qi,Meng, Xiangju,Xiao, Feng-Shou
, (2019/06/05)
The development of a catalyst that delivers high activities and selectivities with excellent durability is of great importance. Numerous efficient catalysts suffer from the inherent hydrolysis liabilities, plaguing their practical applications. Herein, we show that this challenge can be tackled by constructing them into superhydrophobic porous frameworks, as exemplified by a water-sensitive phosphite ligand, tris(2-tert-butylphenyl) phosphite. The efficiency and long-term stability of the developed system are remarkably high in the hydroformylation of internal olefins after metalation with Rh species, superior to the corresponding homogeneous analogues. The significantly boosted hydrolytic stability allows for catalytic transformations using water as a green solvent, which not only facilitates the isolation of the products, but also furnishes the aldehydes with higher regioselectivities for the desired linear form in comparison with that operated under benchmark conditions using toluene as a reaction medium. Given these promising results, we anticipate the strategy advanced herein will form the basis for constructive perspectives in the enhancement of the water resistance of catalysts and the development of high performance hydroformylation catalysts.
Determining the necessity of phenyl ring π-character in warfarin
Xing, Hui,Houston, Sevan D.,Chen, Xuejie,Jin, Da-Yun,Savage, G. Paul,Tie, Jian-Ke,Williams, Craig M.
supporting information, p. 1954 - 1956 (2019/06/04)
Despite the difficulty in administering a safe dose regimen and reports of emerging resistance, warfarin (1) remains the most widely-used oral anticoagulant for the prevention and treatment of thrombosis in humans globally. Systematic substitution of the warfarin phenyl ring with either 1,3,5,7-cyclooctatetraene (COT) (2), cubane (3), cyclohexane (4) or cyclooctane (5) and subsequent evaluation against the target enzyme, vitamin K epoxide reductase (VKOR), facilitated interrogation of both steric and electronic properties of the phenyl pharmacophore. The tolerance of VKOR to further functional group modification (carboxylate 14, PTAD adduct 15) was also investigated. The results demonstrate the importance of both annulene conferred π-interactions and ring size in the activity of warfarin.
Supported rhodium liquid metal catalysts for the hydroformylation of olefins
Sun, Hao,Guo, Wanwan,Liu, Junmei,Feng, Zhipeng,Li, Ruyue,Zhou, Xuyang,Huang, Jun
, (2018/09/25)
The hydroformylation of olefins in supported room temperature liquid metals was developed, and the supported Rh liquid metal catalysts (Rh SLMCs) showed unprecedented activity and high selectivity for the hydroformylation of olefins to aldehydes. The turnover frequency is up to 7000?h?1, much higher than that of homogeneous RhCl3?+?3PPh3 catalyst. Moreover, the Rh SLMCs can be recovered conveniently without obvious deactivation, and the total turnover number is up to 250?000. The active Rh(I) catalyst formed in situ can be reduced back to Rh(0) by the free electrons in liquid metal when H2/CO gas is emitted, and thus Rh is not leaked into the organic solvent. Long-chain olefins, cycloolefins and styrenes were applied, and the corresponding aldehydes were obtained in good to excellent yields.
Phosphonium-based aminophosphines as bifunctional ligands for sequential catalysis of one-pot hydroformylation-acetalization of olefins
Wang, Peng,Liu, Huan,Li, Yong-Qi,Zhao, Xiao-Li,Lu, Yong,Liu, Ye
, p. 3854 - 3861 (2016/06/14)
A series of ionic phosphonium-based aminophosphines L1-L3 were prepared and fully characterized, in each of which the involved bifunctional moieties of the phosphine fragment and Lewis acidic phosphonium were linked together by stable chemical bonds and bridged by one N-atom. The molecular structure of the L2-ligated Rh-complex (Rh-L2) indicated that such bifunctionalities were well retained without incompatibility problems. Investigations on co-catalysis over L1-L3 showed that L3 exhibited the best sequential catalysis for both hydroformylation and acetalization. The phosphine fragment in L3 was responsible for hydroformylation together with the Rh-complex and the phosphonium acted as the Lewis acidic catalyst in charge of acetalization. The L3-Rh(acac)(CO)2 system also exhibited good generality to hydroformylation-acetalization of a wide range of olefins in different alcohols.
An Effective Pd-Catalyzed Regioselective Hydroformylation of Olefins with Formic Acid
Ren, Wenlong,Chang, Wenju,Dai, Jie,Shi, Yuan,Li, Jingfu,Shi, Yian
supporting information, p. 14864 - 14867 (2016/11/29)
An effective palladium-catalyzed regioselective hydroformylation of olefins with formic acid is described. The ligand plays a crucial role in directing the reaction pathway. Linear aldehydes can be obtained in up to 93% yield with >20:1 regioselectivity using 1,3-bis(diphenylphosphino)propane (dppp) as the ligand. The reaction process is operationally simple and requires no syngas.
Selective oxidation of hydrocarbons under air using recoverable silver ferrite-graphene (AgFeO2-G) nanocomposite: A good catalyst for green chemistry
Hosseini, Seyed Majid,Hosseini-Monfared, Hassan,Abbasi, Vahideh,Khoshroo, Mohammad Reza
, p. 72 - 79 (2016/04/10)
The selective oxidation of hydrocarbons is a main academic and industrial research challenge. A lot of researches have been done about this issue, but till now relatively little attention has been paid to graphene-complex oxide nanocomposites. Herein, we report our studies on a new catalyst. Silver ferrite-graphene (AgFeO2-G) as a separable nanocomposite from the reaction solution, was used as an effective oxidizing agent for the oxidation of various hydrocarbons (1- decene, cyclohexene, cis-cycloctene, cyclohexane, cyclooctane etc.) under mild conditions (55 °C, 8 h) with high conversion and selectivity using air, that is proper for 'green' chemistry. Metal or metal oxide nanoparticles assembled on graphene sheets revealed high electrocatalytic activity. Indeed, AgFeO2 with graphene due to low band gap and graphene oxide with large amounts of oxygen-containing groups, provide facility catalytic activity of catalyst-supported system. We also found that, with this catalyst, selective oxidation could be achieved without the need for the addition of solvent, which is appropriate in particular for 'green' chemistry. The catalysts showed little deactivation and maintained their conversion and selectivity levels duration of the measurements.
Decreasing Side Products and Increasing Selectivity in the Tandem Hydroformylation/Acyloin Reaction
Ostrowski, Karoline A.,Fassbach, Thiemo A.,Vogelsang, Dennis,Vorholt, Andreas J.
, p. 2607 - 2613 (2015/09/15)
A highly selective catalyst system was developed for the recently discovered tandem hydroformylation/acyloin reaction by systematic investigations and changes of reaction conditions. This new catalyst system is characterized by an excellent selectivity of the desired reaction pathway with negligible amounts of side products. A successful application of the tandem hydroformylation/acyloin reaction to a variety of olefins is enabled with comparable excellent selectivities up to >99% for the first and second reaction step, therefore a general synthesis for the conversion of olefins into acyloins is found. Furthermore, very good to excellent yields for the intermediates and final acyloin products were observed within two catalysed reactions in one preparative step. The acyloin product was applied as a nonpolar precursor for surfactants. After attaching a polar head group to the acyloin and determination of tensiometric data, the molecule showed industrial relevant surface-active properties. Jointly successful: New catalyst systems for the tandem hydroformylation/acyloin reaction display excellent selectivities within two catalyzed reactions in one preparative step. A variety of olefins can be converted efficiently, and the acyloin product is applied successfully as a nonpolar precursor for surfactants.
