Continuous-Flow Alkane Dehydrogenation by Supported Pincer-Ligated Iridium Catalysts at Elevated Temperatures

ACS Catalysis ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 7828-7841 ◽  
Author(s):  
Boris Sheludko ◽  
Molly T. Cunningham ◽  
Alan S. Goldman ◽  
Fuat E. Celik
Keyword(s):  
Continuous Flow ◽  
Elevated Temperatures ◽  
Iridium Catalysts ◽  
Alkane Dehydrogenation

scholarly journals The Eschenmoser coupling reaction under continuous-flow conditions

2011 ◽  
Vol 7 ◽  
pp. 1164-1172 ◽  
Author(s):  
Sukhdeep Singh ◽  
J Michael Köhler ◽  
Andreas Schober ◽  
G Alexander Groß
Keyword(s):  
Continuous Flow ◽  
Elevated Temperatures ◽  
Reaction Times ◽  
Coupling Reaction ◽  
Flow Chemistry ◽  
Flow Conditions ◽  
Reaction Conditions ◽  
Bond Forming ◽  
Carbon Carbon Bond ◽  
Reaction Proceeds

The Eschenmoser coupling is a useful carbon–carbon bond forming reaction which has been used in various different synthesis strategies. The reaction proceeds smoothly if S-alkylated ternary thioamides or thiolactames are used. In the case of S-alkylated secondary thioamides or thiolactames, the Eschenmoser coupling needs prolonged reaction times and elevated temperatures to deliver valuable yields. We have used a flow chemistry system to promote the Eschenmoser coupling under enhanced reaction conditions in order to convert the demanding precursors such as S-alkylated secondary thioamides and thiolactames in an efficient way. Under pressurized reaction conditions at about 220 °C, the desired Eschenmoser coupling products were obtained within 70 s residence time. The reaction kinetics was investigated and 15 examples of different building block combinations are given.

Temperature-Controlled Bidirectional Enantioselectivity in Asymmetric Hydrogenation Reactions Utilizing Stereodynamic Iridium Complexes

Synthesis ◽  
2017 ◽  
Vol 49 (15) ◽  
pp. 3485-3494 ◽  
Author(s):  
Max Siebert ◽  
Golo Storch ◽  
Frank Rominger ◽  
Oliver Trapp
Keyword(s):  
Elevated Temperatures ◽  
Asymmetric Hydrogenation ◽  
Iridium Complexes ◽  
Chirality Transfer ◽  
Iridium Catalysts ◽  
Thermal Equilibration ◽  
Hydrogenation Reactions ◽  
Temperature Controlled ◽  
First Time ◽  
Solid State Structures

Stereochemically flexible 2,2(-bis(diphenylphosphino)biphenyl (BIPHEP) ligands were modified with chiral α-substituted carboxylic acid auxiliaries in the 3- and 3′-position. The resulting central-to-axial chirality transfer to the stereochemically flexible chiral axis of the BIPHEP­ core was investigated as well as complexation of these diastereomeric ligands to iridium(I). Solid-state structures of both ligand diastereomers and a diastereomerically pure iridium(I) BIPHEP complex were obtained. Thermal equilibration of the resulting iridium(I) complexes was studied to investigate the stereodynamic properties of the BIPHEP ligands. The iridium(I) complexes without and after pre-catalysis warming in solution — which induces a shift of the diastereomeric ratio — were applied for asymmetric hydrogenation of a prochiral α-substituted acrylic acid, resulting in temperature-controlled bidirectional enantioselectivity of iridium catalysts for the first time. In both cases, enantioenriched (R)-naproxen as well as (S)-naproxen — after re-equilibration of the catalyst at elevated temperatures — was obtained by using the same catalyst.

Rational Design and Synthesis of Highly Active Pincer-Iridium Catalysts for Alkane Dehydrogenation

2009 ◽  
Vol 28 (18) ◽  
pp. 5432-5444 ◽  
Author(s):  
Sabuj Kundu ◽  
Yuriy Choliy ◽  
Gao Zhuo ◽  
Ritu Ahuja ◽  
Thomas J. Emge ◽  
...  
Keyword(s):  
Rational Design ◽  
Iridium Catalysts ◽  
Alkane Dehydrogenation ◽  
Design And Synthesis ◽  
Highly Active

Thermal Resistance of Listeria monocytogenes, Salmonella Heidelberg, and Escherichia coli O157:H7 at Elevated Temperatures†

2004 ◽  
Vol 67 (8) ◽  
pp. 1666-1670 ◽  
Author(s):  
LIHAN HUANG
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Continuous Flow ◽  
Elevated Temperatures ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Flow Apparatus ◽  
D Values ◽  
Salmonella Heidelberg

A continuous-flow apparatus was developed to measure thermal resistance (D- and z-values) of microorganisms at temperatures above 65°C. This apparatus was designed to test whether vegetative microorganisms exhibited unusually high thermal resistance that prevented them from being completely eliminated at temperatures applicable to vacuum-steam-vacuum processes (116 to 157°C). The apparatus was composed of a high-pressure liquid chromatography pump, a heating unit, and a cooling unit. It was designed to measure small D-values (<1 s). Three randomly selected organisms, Listeria monocytogenes, Salmonella Heidelberg, and Escherichia coli O157:H7 suspended in deionized water were tested in the continuous-flow apparatus at temperatures ranging from 60 to 80°C. Studies showed that the D-values of these organisms ranged from 0.05 to 20 s. Heating at 80°C was found to be basically the physical limit of the system. Experimental results showed that L. monocytogenes, Salmonella Heidelberg, and E. coli O157:H7 did not exhibit unusual heat resistance. The conditions used in the vacuum-steam-vacuum processes should have completely inactivated organisms such as L. monocytogenes, Salmonella Heidelberg, and E. coli O157:H7 if present on food surfaces. The complete destruction of bacteria during vacuum-steam-vacuum processes might not occur because the surface temperatures never reached those of the steam temperatures and because bacteria might be hidden beneath the surface and was thus never exposed to the destructive effects of the steam.

Opportunities and Challenges for Nanoparticle Synthesis using Continuous Flow Systems: A Magnetite Nanocluster Case Study

2019 ◽  
Author(s):  
Erika Fong ◽  
Jinkyu Han ◽  
C. Cameron Cornell ◽  
Yong Han
Keyword(s):  
Continuous Flow ◽  
Solvothermal Synthesis ◽  
Elevated Temperatures ◽  
Nanoparticle Synthesis ◽  
Reaction Times ◽  
Reaction Chamber ◽  
Flow Speed ◽  
Magnetite Nanoparticle ◽  
Flow Synthesis ◽  
Nanoparticle Clusters

<div>In this study, we demonstrate a new high temperature flow synthesis system for magnetite nanoparticle clusters. We find that successful synthesis of nanoparticle clusters is dependent on residence time in the reaction chamber and linear flow speed. The long reaction times and elevated temperatures required, combined with the resulting slurry formed with successful magnetite nanocluster synthesis, made this reaction challenging to adapt to a flow system. However, proper design of a continuous flow synthesis platform and synthesis parameter control allows for the adoption of even difficult solvothermal synthesis processes. We discuss the importance of reaction pressure control and reaction duration for successful synthesis of magnetite nanoclusters and address opportunities and challenges associated with adopting solvothermal synthesis to continuous flow synthesis platforms.</div>

Highly Active Iridium Catalysts for Alkane Dehydrogenation. Synthesis and Properties of Iridium Bis(phosphine) Pincer Complexes Based on Ferrocene and Ruthenocene

2006 ◽  
Vol 25 (22) ◽  
pp. 5466-5476 ◽  
Author(s):  
Sergey A. Kuklin ◽  
Alexey M. Sheloumov ◽  
Fedor M. Dolgushin ◽  
Mariam G. Ezernitskaya ◽  
Alexander S. Peregudov ◽  
...  
Keyword(s):  
Pincer Complexes ◽  
Iridium Catalysts ◽  
Alkane Dehydrogenation ◽  
Highly Active

Opportunities and Challenges for Nanoparticle Synthesis using Continuous Flow Systems: A Magnetite Nanocluster Case Study

2019 ◽  
Author(s):  
Erika Fong ◽  
Jinkyu Han ◽  
C. Cameron Cornell ◽  
Yong Han
Keyword(s):  
Continuous Flow ◽  
Solvothermal Synthesis ◽  
Elevated Temperatures ◽  
Nanoparticle Synthesis ◽  
Reaction Times ◽  
Reaction Chamber ◽  
Flow Speed ◽  
Magnetite Nanoparticle ◽  
Flow Synthesis ◽  
Nanoparticle Clusters

<div>In this study, we demonstrate a new high temperature flow synthesis system for magnetite nanoparticle clusters. We find that successful synthesis of nanoparticle clusters is dependent on residence time in the reaction chamber and linear flow speed. The long reaction times and elevated temperatures required, combined with the resulting slurry formed with successful magnetite nanocluster synthesis, made this reaction challenging to adapt to a flow system. However, proper design of a continuous flow synthesis platform and synthesis parameter control allows for the adoption of even difficult solvothermal synthesis processes. We discuss the importance of reaction pressure control and reaction duration for successful synthesis of magnetite nanoclusters and address opportunities and challenges associated with adopting solvothermal synthesis to continuous flow synthesis platforms.</div>

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