Hiroshi Nakazawa
Osaka City University, Japan
Title: Effective dehydrogenation of alcohol catalyzed by iron complexes
Biography
Biography: Hiroshi Nakazawa
Abstract
Many methods of transition metal-catalyzed oxidation of alcohols have been developed using oxidants such as oxygen and hydrogen peroxide and hydrogen acceptors such as alkenes and acetones. Recently, oxidant-free and hydrogen acceptor-less dehydrogenation reaction of alcohols have been developed. However, all these catalysts reported to date are highly toxic and precious transition metals. We here, report an unprecedented iron-catalyzed dehydrogenation of alcohols in the absence of hydrogen acceptors. After various combinations of alcohols and iron complexes, we found that (ï¨5-C5H5)Fe(CO)2Cl has excellent catalytic activity for the oxidation of 2-pyridylmethanol derivatives to the corresponding dehydrogenative products with evolution of hydrogen gas. The catalytic activity of the iron complex was enhanced by the addition of 2 mol% of NaH-based on the alcohols. In particular, 2-pyridylbenzylalcohol was quantitatively converted to 2-benzoylpyridine. The hydrogenation could also be achieved even when the amount of the iron complex was reduced from 1 to 0.001 mol%. The highest turnover number achieved was 67000. A possible catalytic cycle will be discussed for the dehydrogenation of 2-pyridylmethanol derivatives catalyzed by (ï¨5-C5H5)Fe(CO)2Cl and NaH.