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本文研究了丙烯氢甲酰化反应体系中氧对铑膦络合物催化性能的影响。实验表明,在本研究条件下,约几倍于自由配体PPh_3量的氧即可使铑膦催化剂活性严重丧失。由动力学实验结果及紫外、红外光谱测定充分证明,氧存在下配体PPh_3被氧化成OPPh_3,PPh_3的消失是引起催化剂失活的根本原因。用加温加压“原位”红外光谱追踪反应过程中催化剂的变化表明,铑膦络合物催化剂因PPh_3的消失而使其活性物种破坏是催化剂失活的本质。实验进一步证明,氧存在下中心金属离子RhI未受影响,重新引入PPh_3会使失活催化剂恢复活性。
In this paper, the effect of oxygen on the catalytic performance of rhodium phosphine complexes in propane hydroformylation was investigated. Experiments show that under the conditions of this study, about several times the free ligand PPh_3 amount of oxygen rhodium phosphine catalyst activity can be a serious loss. The results of kinetic experiments and UV and IR measurements show that the disappearance of PPh_3 and PPh_3 in the presence of oxygen is the basic reason for the deactivation of the catalyst. The change of the catalyst during the reaction was observed by the “in-situ” infrared spectroscopy of the heating and pressurization. The results showed that the destruction of the active species due to the disappearance of PPh_3 was the nature of catalyst deactivation. The experiment further proves that the central metal ion RhI is not affected in the presence of oxygen, and the reintroduction of PPh_3 will restore the activity of the deactivated catalyst.