Selective hydrogenation of conjugated dienes catalyzed by thiocyanatotris(triphenylphosphine)cobalt(I).
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概要
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Thiocyanatotris(triphenylphosphine)cobalt(I) prepared <I>in situ</I> from bis(thiocyanato)bis(triphenylphosphine)cobalt(II), triphenylphosphine, zinc bromide, selectively hydrogenated conjugated dienes to the corresponding cis-monomenes. The C<SUB>2</SUB>-or/and C<SUB>3</SUB>-methyl substituted 1,3-butadienes enhance the reactivity by a factor of 2.3 per one methyl group, while C<SUB>1</SUB>- or/and C<SUB>4</SUB>-methyl substituted 1,3-butadienes lower the reactivity by a factor of 1/23 per one methyl group. In the hydrogenation of cyclic conjugated dienes α-angle (∠C–C=C) is closely related to the hydrogenation rate. The rates of hydrogenation in cyclic ethers are greater than those in acyclic ethers, but the cis-selectivity in acyclic ethers is much higher. Deuterium selectively adds to 1,3-butadiene and 2,5-norbornadiene (bicyclo[2.2.1]hepta-2,5-diene) to give 3,4-dideuterio-1-butene and <I>cis</I>-1,4-dideuterio-2-butene, and <I>endo</I>,<I>endo</I>-5,6-dideuterionorbornene and <I>endo</I>,<I>endo</I>-3,5-dideuterionortricyclene, respectively. A mechanism is proposed which derives from <I>anti</I>-π-allylcobalt hydride or delocalized nortricyclenylcobalt hydride as an intermediate.
- 公益社団法人 日本化学会の論文