摘要
莰烯的氢甲酰化(100℃,10 MPa CO+H_2)因铑-膦络物中膦配体的不同而给出完全不同的产物.圆锥角较大的膦配体倾向于给出更多的exo-产物.双齿膦配体圆锥角虽较小,但因生成双膦桥联的铑络合物而使加氢能力下降,所以只得到较低转化率的endo-莰基醛.本文还以红外光谱研究了活性催化物种并讨论了exo-,endo-产物的生成机制.
Hydroformylation of camphene in the presence of [ ( COD )-RhCl]_2 and various phosphine ligands under 10 MPa syngas [ CO/H_2 = 1 ), 100℃ has been investigated. The active catalyst has been demonstrated by the infrared spectra to be the HRh (CO) L. (for bidentates, m = l; for monodentates, m= 2 ). The selectivity to exo- or endo-products (aldehyde and/or alcohol ) is found to be decided by the cone angle of the ligand carried by the rhodium carbonyl. The larger ligands such as P(o-Tolyl)_3 tend to make the rhodium complex approach the double bond from endo side、 and then to give more exo-alcohol because of the attack of the hydrogen occurs from the cis position with the complex. The bidentate phosphine ligands ( BPPF, bppm, dppb and BINAP) which have relatively smaller cone angles, are expected to give more endoproduct. However, the enhanced stability of Rh-Rh bond that arises from the formation of the phosphine-bridged bimetallic rhodium carbonyls limits the formation of the chelated active species, so that only the endo-aldehydes with relatively lower conversion are observed. The possible mechanism of exo- and endoproduct formations has also been discussed.
出处
《分子催化》
EI
CAS
CSCD
1989年第4期262-268,共7页
Journal of Molecular Catalysis(China)
