A comparative study on photocatalytic hydrogen transfer and catalytic hydrogenation of norbornadiene and quadricyclane catalyzed by [Rh 6(CO) 16]

A comparative study on the hydrogenation of norbornadiene ( I) and quadricyclane ( II) was performed over photo-assisted activated [Rh 6(CO) 16] with or without UV-light irradiation. The photochemical and usual hydrogenations proceeded similarly as shown in reaction scheme. The photo-assisted cataly...

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Published inJournal of molecular catalysis. A, Chemical Vol. 202; no. 1; pp. 31 - 39
Main Authors Akioka, Takanori, Inoue, Yoshiharu, Yanagawa, Akihisa, Hiyamizu, Makoto, Takagi, Yuzuru, Sugimori, Akira
Format Journal Article
LanguageEnglish
Published Amsterdam Elsevier B.V 01.08.2003
Elsevier
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Summary:A comparative study on the hydrogenation of norbornadiene ( I) and quadricyclane ( II) was performed over photo-assisted activated [Rh 6(CO) 16] with or without UV-light irradiation. The photochemical and usual hydrogenations proceeded similarly as shown in reaction scheme. The photo-assisted catalytic transfer hydrogenation and the catalytic hydrogenation of norbornadiene ( I) and quadricyclane ( II) over a photo-activated Rh cluster in 2-propanol in the presence of acetone was studied under comparative conditions. With the photo-assisted catalytic transfer hydrogenation, the hydrogen produced by dehydrogenation of 2-propanol is used very effectively for the addition to the reactants without evolving H 2. Norbornane ( IV) and nortricyclene ( V) are formed in parallel in the photo-assisted hydrogen transfer reaction of II. In the reaction of I, the acetone-sensitized isomerization of I to II occurs prior to hydrogenation in a concentration of 58 mmol/l of I. However, at a lower concentration, we observed a stepwise hydrogenation of I to IV via norbornene ( III). The yield of III formed in the catalytic hydrogenation was larger than that in the photo-assisted catalytic transfer hydrogenation. Compound II was not observed in the catalytic hydrogenation of I, and the yield of V was less than 1%. Compound II behaves in catalytic hydrogenation similar to as in photo-assisted catalytic transfer hydrogenation. The hydrogenation paths of I and II in both the reactions are discussed on the basis of a reaction mechanism shown in Scheme 1.
ISSN:1381-1169
1873-314X
DOI:10.1016/S1381-1169(03)00201-2