1993 Fiscal Year Final Research Report Summary
Mechanically-controlled Chemical Reaction
| Project/Area Number |
04453001
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
物理化学一般
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| Research Institution | (Faculty of Engineering) Hokkaido University |
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Principal Investigator |
ICHIKAWA Tsumeki Hokkaido Univ., fac. of Eng. Associate Professor, 工学部, 助教授 (10001942)
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| Co-Investigator(Kenkyū-buntansha) |
TACHIKAWA Hiroto Hokkaido Univ., fac. of Eng. Instructor, 工学部, 助手 (10207045)
KOIZUMI Hitoshi Hokkaido Univ., fac. of Eng. Instructor, 工学部, 助手 (00175324)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Hydrogen abstraction / Hydrogen addition / Low-temperature chemistry / Tunneling reaction / Non-adiabstic reaction / New reaction theory |
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| Research Abstract |
The rate of hydrogen-atom abstraction from a carbon atom in a organic molecules by a hydrogen atom in a cryogenic solid has been found to increase with the decrease of not only the activation energy for the abstraction but also the steric hindrance to relief of strain for a hydrogen-abstracted carbon atom from sp^3 to sp^2+p, which increases with increasing number and length of alkyl chains bounded to the hydrogen-abstracted carbon atom.
Intramolecular locatin of hydrogen-atom addition to alkenes in a deuterated methanol matrix at 77 K has been found to depend solely on the activation energy for the addition. However, the intramolecular location in a cryogenic adamatance matrix depends not lnly on the activation energy but also on the steric hindrance to relief of strain for a hydrogen-added carbon atom from sp^2+p to SP^3.
Difference of the effect of the steric hindrance arises from the difference of the strength of reactive interaction between the hydrogen atom and an organic molecule. For a strongly-interacting non-adiabatic reactino system such as hydrogen-atom addition in a methanol matrix, because of branching transitions from a reactant system to product systems, the system never come back to the reactant system once it goes into the product system. For a weakly-interacting system, won the other hand, the reactant system is possible to be coupled with ony a small number of product system. The system therefore resonates between the reactant and the product system. The sytsem is stabilized to the product oe by the relief of the strain, so that the rate of the relief or relaxation determins the rate of reaction.
These findings suggest a possibility that the rate of chemical reactino is artificially controlled. for example protection of a specific atom from a chemical reaction can be attained by immobilizing the atom with the aid of a rigid matrix, external pressure, or adsorption.
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