1988 Fiscal Year Final Research Report Summary
Development of Catalysts for Epoxidation of Olefins
| Project/Area Number |
61850154
|
|---|
| Research Category |
Grant-in-Aid for Developmental Scientific Research
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Synthetic chemistry
|
|---|
| Research Institution | Kyushu University |
|---|
Principal Investigator |
MATSUDA Yoshihisa Kyushu University, 工学部, 助教授 (10037757)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
盛満 耕造 出光興産, 中研, 研究主任
熊沢 尚 出光興産, 中研, 研究主任
HISAEDA Yoshio Kyushu University, 工学部, 助教授 (70150498)
MORIMITSU Kozo Idemitsu Kosan
KUMASAWA Takashi Idemitsu Kosan
|
|---|
| Project Period (FY) |
1986 – 1988
|
| Keywords | Early transition metals / Porphyrin complexes / Photoredox chemistry / Epoxidation / エポキシ化反応 / 時間分解ESR / 軸配位子の反応 / 三重項ラジカル対 |
|---|
| Research Abstract |
Niobium(V) and molybdenum(V) porphyrins were prepared. Molybdenum complexes had an octahedral structure with an oxo and an alkoxo ligand on their axial site, while tri-u-oxo dimer of niobium(V) porphyrins had cis-hepta-coordinated one. Complexes catalyzed photochemical epoxidation of olefins in benzene upon aerobic irradiation of with visible light. Photochemical reactions of above complexes were followed by means of visible absorption and ESR spectroscopy.
Nionium(V) and molybdenum(V) porphyrins were reduced in benzene upon anaerobic irradiation with visible light affording corresponding pentacoordinate complexes. Homolysis of an axial coordination bond took place during the photoreduction and axial ligands were released as corresponding radical species. The reduced complexes were oxidized in benzene by molecular oxygen upon aeration resuting superoxide complexes. The superoxide complexes transferred an oxygen atom to an olefin added in the soultion to form corresponding epoxide.
The photoreduction of the complexes was revealed by means of time-resolved ESR spectroscopy. The photoreduction, the homolysis of the axial coordination bond, proceeded via a charge transfer triplet state and a triplet pair of a radical and a reduced central metal. The superoxide complex was formed by reaction of molecular oxygen with the triplet pair. Addition of molecules which could coordinate at the axial site of the complexes disturbed the formation of the superoxide complexes.
No cis-trans isomerization took place in the photo-epoxidation process suggesting an ionic nature of the intermediate. Olefins having a terminal double bond showed lower activity than ones having an internal duble bond. Olefins with more alkyl substituent groups had higher activity than those with less substituent groups. Introduction of picket fence type substituents into the porphyrin ligand improved both activity and selectivity.
|
Research Products
(7 results)
