The Experts below are selected from a list of 147 Experts worldwide ranked by ideXlab platform

Dongju Zhang - One of the best experts on this subject based on the ideXlab platform.

  • theoretical elucidation of the mechanism and kinetic experimental phenomena on the esterification of α tocopherol with succinic anhydride catalysis of a Histidine Derivative vs an imidazolium based ionic liquid
    Journal of Organic Chemistry, 2017
    Co-Authors: Yaru Jing, Dongju Zhang
    Abstract:

    DFT calculations have been conducted to gain insight into the mechanism and kinetics of the esterification of α-tocopherol with succinic anhydride catalyzed by a Histidine Derivative or an imidazolium-based ionic liquid (IL). The two catalytic reactions involve an intrinsically consistent molecular mechanism: a rate-determining, concerted nucleophilic substitution followed by a facile proton-transfer process. The Histidine Derivative or the IL anion is shown to play a decisive role, acting as a Bronsted base by abstracting the hydroxyl proton of α-tocopherol to favor the nucleophilic substitution of the hydroxyl oxygen of α-tocopherol on succinic anhydride. The calculated free energy barriers of two reactions (15.8 kcal/mol for the histamine-catalyzed reaction and 22.9 kcal/mol for the IL-catalyzed reaction) together with their respective characteristic features, the catalytic reaction with a catalytic amount of histamine vs the catalytic reaction with an excessed amount of the IL, rationalize well the ex...

  • Theoretical Elucidation of the Mechanism and Kinetic Experimental Phenomena on the Esterification of α-Tocopherol with Succinic Anhydride: Catalysis of a Histidine Derivative vs an Imidazolium-Based Ionic Liquid
    Journal of Organic Chemistry, 2017
    Co-Authors: Yaru Jing, Chengbu Liu, Rongxiu Zhu, Dongju Zhang
    Abstract:

    © 2017 American Chemical Society. DFT calculations have been conducted to gain insight into the mechanism and kinetics of the esterification of α-tocopherol with succinic anhydride catalyzed by a Histidine Derivative or an imidazolium-based ionic liquid (IL). The two catalytic reactions involve an intrinsically consistent molecular mechanism: a rate-determining, concerted nucleophilic substitution followed by a facile proton-transfer process. The Histidine Derivative or the IL anion is shown to play a decisive role, acting as a Brönsted base by abstracting the hydroxyl proton of α-tocopherol to favor the nucleophilic substitution of the hydroxyl oxygen of α-tocopherol on succinic anhydride. The calculated free energy barriers of two reactions (15.8 kcal/mol for the histamine-catalyzed reaction and 22.9 kcal/mol for the IL-catalyzed reaction) together with their respective characteristic features, the catalytic reaction with a catalytic amount of histamine vs the catalytic reaction with an excessed amount of the IL, rationalize well the experimentally observed kinetics that the former has faster initial rate but longer reaction time while the latter is initiated slowly but completed in a much shorter time.

Yaru Jing - One of the best experts on this subject based on the ideXlab platform.

  • theoretical elucidation of the mechanism and kinetic experimental phenomena on the esterification of α tocopherol with succinic anhydride catalysis of a Histidine Derivative vs an imidazolium based ionic liquid
    Journal of Organic Chemistry, 2017
    Co-Authors: Yaru Jing, Dongju Zhang
    Abstract:

    DFT calculations have been conducted to gain insight into the mechanism and kinetics of the esterification of α-tocopherol with succinic anhydride catalyzed by a Histidine Derivative or an imidazolium-based ionic liquid (IL). The two catalytic reactions involve an intrinsically consistent molecular mechanism: a rate-determining, concerted nucleophilic substitution followed by a facile proton-transfer process. The Histidine Derivative or the IL anion is shown to play a decisive role, acting as a Bronsted base by abstracting the hydroxyl proton of α-tocopherol to favor the nucleophilic substitution of the hydroxyl oxygen of α-tocopherol on succinic anhydride. The calculated free energy barriers of two reactions (15.8 kcal/mol for the histamine-catalyzed reaction and 22.9 kcal/mol for the IL-catalyzed reaction) together with their respective characteristic features, the catalytic reaction with a catalytic amount of histamine vs the catalytic reaction with an excessed amount of the IL, rationalize well the ex...

  • Theoretical Elucidation of the Mechanism and Kinetic Experimental Phenomena on the Esterification of α-Tocopherol with Succinic Anhydride: Catalysis of a Histidine Derivative vs an Imidazolium-Based Ionic Liquid
    Journal of Organic Chemistry, 2017
    Co-Authors: Yaru Jing, Chengbu Liu, Rongxiu Zhu, Dongju Zhang
    Abstract:

    © 2017 American Chemical Society. DFT calculations have been conducted to gain insight into the mechanism and kinetics of the esterification of α-tocopherol with succinic anhydride catalyzed by a Histidine Derivative or an imidazolium-based ionic liquid (IL). The two catalytic reactions involve an intrinsically consistent molecular mechanism: a rate-determining, concerted nucleophilic substitution followed by a facile proton-transfer process. The Histidine Derivative or the IL anion is shown to play a decisive role, acting as a Brönsted base by abstracting the hydroxyl proton of α-tocopherol to favor the nucleophilic substitution of the hydroxyl oxygen of α-tocopherol on succinic anhydride. The calculated free energy barriers of two reactions (15.8 kcal/mol for the histamine-catalyzed reaction and 22.9 kcal/mol for the IL-catalyzed reaction) together with their respective characteristic features, the catalytic reaction with a catalytic amount of histamine vs the catalytic reaction with an excessed amount of the IL, rationalize well the experimentally observed kinetics that the former has faster initial rate but longer reaction time while the latter is initiated slowly but completed in a much shorter time.

Chengbu Liu - One of the best experts on this subject based on the ideXlab platform.

  • Theoretical Elucidation of the Mechanism and Kinetic Experimental Phenomena on the Esterification of α-Tocopherol with Succinic Anhydride: Catalysis of a Histidine Derivative vs an Imidazolium-Based Ionic Liquid
    Journal of Organic Chemistry, 2017
    Co-Authors: Yaru Jing, Chengbu Liu, Rongxiu Zhu, Dongju Zhang
    Abstract:

    © 2017 American Chemical Society. DFT calculations have been conducted to gain insight into the mechanism and kinetics of the esterification of α-tocopherol with succinic anhydride catalyzed by a Histidine Derivative or an imidazolium-based ionic liquid (IL). The two catalytic reactions involve an intrinsically consistent molecular mechanism: a rate-determining, concerted nucleophilic substitution followed by a facile proton-transfer process. The Histidine Derivative or the IL anion is shown to play a decisive role, acting as a Brönsted base by abstracting the hydroxyl proton of α-tocopherol to favor the nucleophilic substitution of the hydroxyl oxygen of α-tocopherol on succinic anhydride. The calculated free energy barriers of two reactions (15.8 kcal/mol for the histamine-catalyzed reaction and 22.9 kcal/mol for the IL-catalyzed reaction) together with their respective characteristic features, the catalytic reaction with a catalytic amount of histamine vs the catalytic reaction with an excessed amount of the IL, rationalize well the experimentally observed kinetics that the former has faster initial rate but longer reaction time while the latter is initiated slowly but completed in a much shorter time.

Rongxiu Zhu - One of the best experts on this subject based on the ideXlab platform.

  • Theoretical Elucidation of the Mechanism and Kinetic Experimental Phenomena on the Esterification of α-Tocopherol with Succinic Anhydride: Catalysis of a Histidine Derivative vs an Imidazolium-Based Ionic Liquid
    Journal of Organic Chemistry, 2017
    Co-Authors: Yaru Jing, Chengbu Liu, Rongxiu Zhu, Dongju Zhang
    Abstract:

    © 2017 American Chemical Society. DFT calculations have been conducted to gain insight into the mechanism and kinetics of the esterification of α-tocopherol with succinic anhydride catalyzed by a Histidine Derivative or an imidazolium-based ionic liquid (IL). The two catalytic reactions involve an intrinsically consistent molecular mechanism: a rate-determining, concerted nucleophilic substitution followed by a facile proton-transfer process. The Histidine Derivative or the IL anion is shown to play a decisive role, acting as a Brönsted base by abstracting the hydroxyl proton of α-tocopherol to favor the nucleophilic substitution of the hydroxyl oxygen of α-tocopherol on succinic anhydride. The calculated free energy barriers of two reactions (15.8 kcal/mol for the histamine-catalyzed reaction and 22.9 kcal/mol for the IL-catalyzed reaction) together with their respective characteristic features, the catalytic reaction with a catalytic amount of histamine vs the catalytic reaction with an excessed amount of the IL, rationalize well the experimentally observed kinetics that the former has faster initial rate but longer reaction time while the latter is initiated slowly but completed in a much shorter time.

Caroline Gaucher - One of the best experts on this subject based on the ideXlab platform.

  • Selenoneine: a Unique Reactive Selenium Species From the Blood of Tuna With Implications for Human Diseases
    Current Pharmacology Reports, 2019
    Co-Authors: Rama Alhasan, Muhammad Jawad Nasim, Claus Jacob, Caroline Gaucher
    Abstract:

    Purpose of Review The trace element selenium is found in many dietary components, from grains to Brazil nuts. In humans, this chalcogen is essential for many physiological processes. A couple of years ago, selenoneine, a rather unusual seleno-Histidine Derivative, has been isolated from tuna. Recent Findings Whilst there is a limited number of other naturally occurring small selenium compounds, large quantities of selenoneine can be generated in genetically engineered microorganisms and via chemical synthesis. Due to a rare selenol/selenone tautomerism, this compound exhibits unique redox properties and promising biological activities, which range of traditional antioxidant action to the interaction and subsequent protection of metal ions. Summary Selenoneine may indeed provide a promising lead for a new generation of selenium supplements and chemopreventive agents.

  • Selenoneine: a Unique Reactive Selenium Species From the Blood of Tuna With Implications for Human Diseases
    Current Pharmacology Reports, 2019
    Co-Authors: Rama Alhasan, Muhammad Jawad Nasim, Claus Jacob, Caroline Gaucher
    Abstract:

    The trace element selenium is found in many dietary components, from grains to Brazil nuts. In humans, this chalcogen is essential for many physiological processes. A couple of years ago, selenoneine, a rather unusual seleno-Histidine Derivative, has been isolated from tuna. Whilst there is a limited number of other naturally occurring small selenium compounds, large quantities of selenoneine can be generated in genetically engineered microorganisms and via chemical synthesis. Due to a rare selenol/selenone tautomerism, this compound exhibits unique redox properties and promising biological activities, which range of traditional antioxidant action to the interaction and subsequent protection of metal ions. Selenoneine may indeed provide a promising lead for a new generation of selenium supplements and chemopreventive agents.