scholarly journals Thermoregulated phase-separable rhodium nanoparticle catalyst for selective hydrogenation of α,β-unsaturated aldehydes and ketones

RSC Advances ◽  
2017 ◽  
Vol 7 (79) ◽  
pp. 50343-50346 ◽  
Author(s):  
Xiuru Xue ◽  
Mingming Niu ◽  
Yicheng Xu ◽  
Yanhua Wang
Keyword(s):  
Selective Hydrogenation ◽  
Unsaturated Aldehydes ◽  
Highly Efficient ◽  
Aldehydes And Ketones ◽  
Rhodium Nanoparticle ◽  
Nanoparticle Catalyst

Highly efficient and recyclable thermoregulated phase-separable Rhnano catalysts applied for the selective hydrogenation of α,β-unsaturated aldehydes and ketones are presented.

Thermoregulated phase-transfer iridium nanoparticle catalyst: highly selective hydrogenation of the CO bond for α,β-unsaturated aldehydes and the CC bond for α,β-unsaturated ketones

2016 ◽  
Vol 6 (20) ◽  
pp. 7386-7390 ◽  
Author(s):  
Wenjiang Li ◽  
Yanhua Wang ◽  
Pu Chen ◽  
Min Zeng ◽  
Jingyang Jiang ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
Phase Transfer ◽  
Unsaturated Ketones ◽  
Iridium Nanoparticles ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Nanoparticle Catalyst

Thermoregulated phase-transfer iridium nanoparticles exhibited a totally different hydrogenation orientation for α,β-unsaturated aldehydes and ketones.

scholarly journals Chemoselective reduction of heteroarenes with a reduced graphene oxide supported rhodium nanoparticle catalyst

2018 ◽  
Vol 8 (19) ◽  
pp. 5091-5097 ◽  
Author(s):  
Alena Karakulina ◽  
Aswin Gopakumar ◽  
Zhaofu Fei ◽  
Paul J. Dyson
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Selective Hydrogenation ◽  
Rhodium Nanoparticles ◽  
Reduced Graphene ◽  
Rhodium Nanoparticle ◽  
Nanoparticle Catalyst

Rhodium nanoparticles immobilized on reduced graphene oxide catalyze the selective hydrogenation of N- and O-containing heteroarenes.

Gold Promotion of MCM-41 Supported Ruthenium Catalysts for Selective Hydrogenation of α,β-Unsaturated Aldehydes and Ketones

2017 ◽  
Vol 148 (1) ◽  
pp. 267-276 ◽  
Author(s):  
Rongrong Li ◽  
Jia Zhao ◽  
Zhixing Gan ◽  
Wenping Jia ◽  
Chenglin Wu ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
Ruthenium Catalysts ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Mcm 41

Selective Hydrogenation of α,β-Unsaturated Aldehydes and Ketones by Air-Stable Ruthenium NNS Complexes

2017 ◽  
Vol 23 (35) ◽  
pp. 8473-8481 ◽  
Author(s):  
Pim Puylaert ◽  
Richard van Heck ◽  
Yuting Fan ◽  
Anke Spannenberg ◽  
Wolfgang Baumann ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones

Selective hydrogenation of the CC bond in α,β-unsaturated aldehydes and ketones over ultra-small Pd–Au clusters

Nanoscale ◽  
2016 ◽  
Vol 8 (44) ◽  
pp. 18626-18629 ◽  
Author(s):  
Yifei Zhang ◽  
Xiujuan Yang ◽  
Yan Zhou ◽  
Gao Li ◽  
Zhimin Li ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
Unsaturated Aldehydes ◽  
Au Clusters ◽  
Aldehydes And Ketones

Hafnium(IV) Chloride Catalyzes Highly Efficient Acetalization of Carbonyl Compounds

2019 ◽  
Vol 16 (6) ◽  
pp. 913-920 ◽  
Author(s):  
Israel Bonilla-Landa ◽  
Emizael López-Hernández ◽  
Felipe Barrera-Méndez ◽  
Nadia C. Salas ◽  
José L. Olivares-Romero
Keyword(s):  
Microwave Heating ◽  
Reaction Times ◽  
Protecting Groups ◽  
Catalyst Loading ◽  
Selective Protection ◽  
Highly Efficient ◽  
Aldehydes And Ketones ◽  
High Yields ◽  
Novel Catalyst ◽  
Acid Labile

Background: Hafnium(IV) tetrachloride efficiently catalyzes the protection of a variety of aldehydes and ketones, including benzophenone, acetophenone, and cyclohexanone, to the corresponding dimethyl acetals and 1,3-dioxolanes, under microwave heating. Substrates possessing acid-labile protecting groups (TBDPS and Boc) chemoselectively generated the corresponding acetal/ketal in excellent yields. Aim and Objective: In this study. the selective protection of aldehydes and ketones using a Hafnium(IV) chloride, which is a novel catalyst, under microwave heating was observed. Hence, it is imperative to find suitable conditions to promote the protection reaction in high yields and short reaction times. This study was undertaken not only to find a novel catalyst but also to perform the reaction with substrates bearing acid-labile protecting groups, and study the more challenging ketones as benzophenone. Materials and Methods: Using a microwave synthesis reactor Monowave 400 of Anton Paar, the protection reaction was performed on a raging temperature of 100°C ±1, a pressure of 2.9 bar, and an electric power of 50 W. More than 40 substrates have been screened and protected, not only the aldehydes were protected in high yields but also the more challenging ketones such as benzophenone were protected. All the products were purified by simple flash column chromatography, using silica gel and hexanes/ethyl acetate (90:10) as eluents. Finally, the protected substrates were characterized by NMR 1H, 13C and APCI-HRMS-QTOF. Results: Preliminary screening allowed us to find that 5 mol % of the catalyst is enough to furnish the protected aldehyde or ketone in up to 99% yield. Also it was found that substrates with a variety of substitutions on the aromatic ring (aldehyde or ketone), that include electron-withdrawing and electrondonating group, can be protected using this methodology in high yields. The more challenging cyclic ketones were also protected in up to 86% yield. It was found that trimethyl orthoformate is a very good additive to obtain the protected acetophenone. Finally, the protection of aldehydes with sensitive functional groups was performed. Indeed, it was found that substrates bearing acid labile groups such as Boc and TBDPS, chemoselectively generated the corresponding acetal/ketal compound while keeping the protective groups intact in up to 73% yield. Conclusion: Hafnium(IV) chloride as a catalyst provides a simple, highly efficient, and general chemoselective methodology for the protection of a variety of structurally diverse aldehydes and ketones. The major advantages offered by this method are: high yields, low catalyst loading, air-stability, and non-toxicity.

scholarly journals Theoretical Insight into the Reversal of Chemoselectivity in Diels-Alder Reactions of α,β-Unsaturated Aldehydes and Ketones Catalyzed by Brønsted and Lewis Acids

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 38-49
Author(s):  
Lakhdar Benhamed ◽  
Sidi Mohamed Mekelleche ◽  
Wafaa Benchouk
Keyword(s):  
Lewis Acids ◽  
Major Product ◽  
Diels Alder ◽  
Unsaturated Ketone ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Theoretical Insight ◽  
Insight Into ◽  
Good Agreement

Experimentally, a reversal of chemoselectivity has been observed in catalyzed Diels–Alder reactions of α,β-unsaturated aldehydes (e.g., (2E)-but-2-enal) and ketones (e.g., 2-hexen-4-one) with cyclopentadiene. Indeed, using the triflimidic Brønsted acid Tf2NH as catalyst, the reaction gave a Diels–Alder adduct derived from α,β-unsaturated ketone as a major product. On the other hand, the use of tris(pentafluorophenyl)borane B(C6F5)3 bulky Lewis acid as catalyst gave mainly the cycloadduct of α,β-unsaturated aldehyde as a major product. Our aim in the present work is to put in evidence the role of the catalyst in the reversal of the chemoselectivity of the catalyzed Diels–Alder reactions of (2E)-but-2-enal and 2-Hexen-4-one with cyclopentadiene. The calculations were performed at the ωB97XD/6-311G(d,p) level of theory and the solvent effects of dichloromethane were taken into account using the PCM solvation model. The obtained results are in good agreement with experimental outcomes.

Sign in / Sign up

Export Citation Format

Share Document