Mechanism of Potassiumtert-Butoxide-Catalyzed Ketones Hydrogenation in the Solution Phase

The Journal of Physical Chemistry A, Journal Year: 2021, Volume and Issue: 125(26), P. 5726 - 5737

Published: June 29, 2021

The mechanism of ketones homogeneous hydrogenation with t-BuOK in tert-butanol is currently portrayed as the one proceeding via a six-membered [2 + 2 2] cyclic transition state involving H2 molecule, base, and ketone. However, concerted nature reaction inconsistent number experimental observations. Here we reanalyze available data revise this paradigmatic based on static dynamic density functional theory (DFT) calculations solution phase. In contrast to gas-phase profile where overall occurs two elementary steps, there are three consecutive steps solution: cleavage H–H bond basic afford potassium hydride, addition hydride across C═O ketone through rate-determining state, rapid product formation K/H exchange. Potassium therefore an important intermediate catalytic process. free energy for prophetic ester also computed herein. seems be kinetically possible, but slightly harsher conditions need applied, consistent addition.

Language: Английский

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Historical and contemporary perspectives on metal–organic frameworks for gas sensing applications: a review

RSC Sustainability, Journal Year: 2023, Volume and Issue: 1(5), P. 1125 - 1149

Published: Jan. 1, 2023

A metal–organic framework (MOF) has the ability to effectively and environmentally friendly store gas through process of capture separation.

Language: Английский

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Biomimetic Frustrated Lewis Pair Catalysts for Hydrogenation of CO to Methanol at Low Temperatures

ACS Organic & Inorganic Au, Journal Year: 2024, Volume and Issue: 4(2), P. 258 - 267

Published: Jan. 31, 2024

The industrial production of methanol through CO hydrogenation using the Cu/ZnO/Al2O3 catalyst requires harsh conditions, and development new catalysts with low operating temperatures is highly desirable. In this study, organic biomimetic FLP good tolerance to poison are theoretically designed. base-free catalytic reaction contains 1,1-addition into a formic acid intermediate methanol. Low-energy spans (25.6, 22.1, 20.6 kcal/mol) achieved, indicating that can be hydrogenated at temperatures. extended aromatization–dearomatization effect involving multiple rings proposed effectively facilitate rate-determining step, activation model for catalysts.

Language: Английский

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Homogeneous Hydrogenation of CO₂ and CO to Methanol: The Renaissance of Low‐Temperature Catalysis in the Context of the Methanol Economy

Angewandte Chemie, Journal Year: 2022, Volume and Issue: 134(42)

Published: Aug. 3, 2022

Abstract The traditional economy based on carbon‐intensive fuels and materials has led to an exponential rise in anthropogenic CO 2 emissions. Outpacing the natural carbon cycle, atmospheric levels increased by 50 % since pre‐industrial age can be directly linked global warming. Being at core of proposed methanol pioneered late George A. Olah, chemical recycling produce methanol, a green fuel feedstock, is prime channel achieve neutrality. In this direction, homogeneous catalytic systems have lately been major focus for synthesis from , their derivatives as potential low‐temperature alternatives commercial processes. This Review provides account rapidly growing field over past decade, its resurgence 2011. Based critical assessment progress thus far, present key challenges highlighted directions suggested practically viable applications.

Language: Английский

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Hydrogenation of CO₂ to MeOH Catalyzed by Highly Robust (PNNP)Ir Complexes Activated by Alkali Bases in Alcohol

Inorganic Chemistry, Journal Year: 2023, Volume and Issue: 62(34), P. 14116 - 14123

Published: Aug. 17, 2023

Despite receiving significant attention, well-defined homogeneous complexes for hydrogenation of carbon dioxide (CO2) to methanol (MeOH) are scarce and suffer issues low catalyst turnover numbers (TONs) at high concentrations deactivation in the presence CO elevated temperatures. Herein, we disclose a system deploying sterically demanded (PNNP)Ir sustained activity CO2 MeOH temperatures ∼200 °C an alcohol solvent. Through reaction optimization, achieved TON ∼9000 formation, which exceeds most active systems reported date, robustness on par with or exceeding reactive utilizing amine additives was demonstrated. The key achieving catalytic amount alkali base additive, serves dual purpose facilitating more efficient outer-sphere reduction HCO2Et enhancing selectivity over situ formed CO.

Language: Английский

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