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Mechanism for microwave heating of 1-(4′-cyanophenyl)-4-propylcyclohexane characterized by in situ microwave irradiation NMR spectroscopy.

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Title: Mechanism for microwave heating of 1-(4′-cyanophenyl)-4-propylcyclohexane characterized by in situ microwave irradiation NMR spectroscopy.
Authors: Tasei, Yugo1, Yamakami, Takuya2, Kawamura, Izuru1, Fujito, Teruaki3, Ushida, Kiminori2, Sato, Motoyasu4, Naito, Akira1 naito@ynu.ac.jp
Source: Journal of Magnetic Resonance. May2015, Vol. 254, p27-34. 8p.
Subjects: Microwave heating, Cyclohexane, Nuclear magnetic resonance spectroscopy, Irradiation, Chemical reactions
Abstract: Microwave heating is widely used to accelerate organic reactions and enhance the activity of enzymes. However, the detailed molecular mechanism for the effect of microwave on chemical reactions is not yet fully understood. To investigate the effects of microwave heating on organic compounds, we have developed an in situ microwave irradiation NMR spectroscopy. 1 H NMR spectra of 1-(4′-cyanophenyl)-4-propylcyclohexane (PCH3) in the liquid crystalline and isotropic phases were observed under microwave irradiation. When the temperature was regulated at slightly higher than the phase transition temperature ( T c = 45 °C) under a gas flow temperature control system, liquid crystalline phase mostly changed to the isotropic phase. Under microwave irradiation and with the gas flow temperature maintained at 20 °C, which is 25 °C below the T c , the isotropic phase appeared stationary as an approximately 2% fraction in the liquid crystalline phase. The temperature of the liquid crystalline state was estimated to be 38 °C according to the line width, which is at least 7 °C lower than the T c . The temperature of this isotropic phase should be higher than 45 °C, which is considered to be a non-equilibrium local heating state induced by microwave irradiation. Microwaves at a power of 195 W were irradiated to the isotropic phase of PCH3 at 50 °C and after 2 min, the temperature reached 220 °C. The temperature of PCH3 under microwave irradiation was estimated by measurement of the chemical shift changes of individual protons in the molecule. These results demonstrate that microwave heating generates very high temperature within a short time using an in situ microwave irradiation NMR spectrometer. [ABSTRACT FROM AUTHOR]
Copyright of Journal of Magnetic Resonance is the property of Academic Press Inc. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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DbLabel: Engineering Source
An: 102458737
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  Data: Mechanism for microwave heating of 1-(4′-cyanophenyl)-4-propylcyclohexane characterized by in situ microwave irradiation NMR spectroscopy.
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  Data: <searchLink fieldCode="AR" term="%22Tasei%2C+Yugo%22">Tasei, Yugo</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Yamakami%2C+Takuya%22">Yamakami, Takuya</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Kawamura%2C+Izuru%22">Kawamura, Izuru</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Fujito%2C+Teruaki%22">Fujito, Teruaki</searchLink><relatesTo>3</relatesTo><br /><searchLink fieldCode="AR" term="%22Ushida%2C+Kiminori%22">Ushida, Kiminori</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Sato%2C+Motoyasu%22">Sato, Motoyasu</searchLink><relatesTo>4</relatesTo><br /><searchLink fieldCode="AR" term="%22Naito%2C+Akira%22">Naito, Akira</searchLink><relatesTo>1</relatesTo><i> naito@ynu.ac.jp</i>
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  Data: <searchLink fieldCode="JN" term="%22Journal+of+Magnetic+Resonance%22">Journal of Magnetic Resonance</searchLink>. May2015, Vol. 254, p27-34. 8p.
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  Data: <searchLink fieldCode="DE" term="%22Microwave+heating%22">Microwave heating</searchLink><br /><searchLink fieldCode="DE" term="%22Cyclohexane%22">Cyclohexane</searchLink><br /><searchLink fieldCode="DE" term="%22Nuclear+magnetic+resonance+spectroscopy%22">Nuclear magnetic resonance spectroscopy</searchLink><br /><searchLink fieldCode="DE" term="%22Irradiation%22">Irradiation</searchLink><br /><searchLink fieldCode="DE" term="%22Chemical+reactions%22">Chemical reactions</searchLink>
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  Data: Microwave heating is widely used to accelerate organic reactions and enhance the activity of enzymes. However, the detailed molecular mechanism for the effect of microwave on chemical reactions is not yet fully understood. To investigate the effects of microwave heating on organic compounds, we have developed an in situ microwave irradiation NMR spectroscopy. 1 H NMR spectra of 1-(4′-cyanophenyl)-4-propylcyclohexane (PCH3) in the liquid crystalline and isotropic phases were observed under microwave irradiation. When the temperature was regulated at slightly higher than the phase transition temperature ( T c = 45 °C) under a gas flow temperature control system, liquid crystalline phase mostly changed to the isotropic phase. Under microwave irradiation and with the gas flow temperature maintained at 20 °C, which is 25 °C below the T c , the isotropic phase appeared stationary as an approximately 2% fraction in the liquid crystalline phase. The temperature of the liquid crystalline state was estimated to be 38 °C according to the line width, which is at least 7 °C lower than the T c . The temperature of this isotropic phase should be higher than 45 °C, which is considered to be a non-equilibrium local heating state induced by microwave irradiation. Microwaves at a power of 195 W were irradiated to the isotropic phase of PCH3 at 50 °C and after 2 min, the temperature reached 220 °C. The temperature of PCH3 under microwave irradiation was estimated by measurement of the chemical shift changes of individual protons in the molecule. These results demonstrate that microwave heating generates very high temperature within a short time using an in situ microwave irradiation NMR spectrometer. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Journal of Magnetic Resonance is the property of Academic Press Inc. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
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      – Type: doi
        Value: 10.1016/j.jmr.2015.02.002
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      – Code: eng
        Text: English
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        PageCount: 8
        StartPage: 27
    Subjects:
      – SubjectFull: Microwave heating
        Type: general
      – SubjectFull: Cyclohexane
        Type: general
      – SubjectFull: Nuclear magnetic resonance spectroscopy
        Type: general
      – SubjectFull: Irradiation
        Type: general
      – SubjectFull: Chemical reactions
        Type: general
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      – TitleFull: Mechanism for microwave heating of 1-(4′-cyanophenyl)-4-propylcyclohexane characterized by in situ microwave irradiation NMR spectroscopy.
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            NameFull: Tasei, Yugo
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            NameFull: Yamakami, Takuya
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            NameFull: Kawamura, Izuru
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            NameFull: Fujito, Teruaki
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            NameFull: Ushida, Kiminori
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              M: 05
              Text: May2015
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              Y: 2015
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              Value: 254
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