| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 1998: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1997: ¥3,200,000 (Direct Cost: ¥3,200,000)
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| Research Abstract |
The novel host-guest catalysts (MMS), in which chiral rhodium complexes as well as structural tuning guests were intercalated into smectites, were synthesized, and drastic change in catalysis was observed depending on the interlayer spacing as well as the orientation of guest molecules.
Preparation of multiple-modified catalysts (MMS) with various interlayer spacings : Smectites modified with structural tuning guests such as primary and quaternary ammoniums (C_nH_<2n+2>NH_3^+(1ﾟC_n), (C_nH_<2n+2>) _2 (CH_3)_2NH_3^+(4ﾟC_n), respectively) have clearance spaces (CS) of 0.37 -1.07 nm for 1ﾟC_n and 1.93-2.88 nm for 4ﾟC_n with changing n from 10 to 18. (2)Control of the orientation of the guest molecules by changing the layer charge of hosts. (3)Catalysis for the asymmetric hydrogenation of prochiral olefins and ketones by MMS : MMS catalysts show higher catalytic activity and selectivity than the corresponding homogeneous ones in the hydrogenation of alpha-pinene and acetophenones at 30 atm of H_2 pressure. These results indicate that MMS catalysts are more stable than the homogeneous ones. (4)Effect of the interlayer spacing and the guest orientation on the catalytic behavior : It is found that the interlayer spacing and the orientation of guests clearly affect the catalytic activity as well as the selectivity, In the hydrogenation of alpha-pinene, Rh-DIOP/C_nN^+/NaHT(CS=2.46-2.78nm) showed the conversions of 1.3-7.3 % with low exo-selectivity of 50-70 %, while Rh-DIOP/C_nN^+/LiTN(CS=1.93-2.88nm) showed much higher conversions over 99.8 % with high exo-selectivity of 92 %. Since LiTN has three times higher layer charge density than NaHT, the orientation of structural tuning guests (C_nN^+) in LiTN was nearly perpendicular to the silicate layer, while that in NaHT was in the range between 58 to 65 degree to the layer sheet. Particularly these guest orientations definitely affect the catalytic activity and selectivity.
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