Infrared spectroscopic investigation of a mixture of CO, H 2 , and 1-butene under conditions that bring

Question:

Infrared spectroscopic investigation of a mixture of CO, H₂, and 1-butene under conditions that bring about hydroformylation indicate the presence of compound (E) in Fig. 22.20 in the reaction mixture. The same reacting mixture in the presence of added tributylphosphine was studied by infrared spectroscopy and neither (E) nor an analogous phosphine-substituted complex was observed. What does the first observation suggest as the rate-limiting reaction in the absence of phosphine? Assuming the sequence of reactions remains unchanged, what are the possible rate-limiting reactions in the presence of tributylphosphine?

Figure 22.20.