Carbonyl Insertion Reactions with Metal Carbonyls and Alkenes

The purpose of this project is to observe carbonyl insertion, or alkyl migration, with a metal catalyst and an alkene. Carbonyl insertion occurs when a carbonyl group (CO) reacts with an alkene-metal complex to give an acyl [-C(=O)R] product. There is a direct insertion of CO into a metal-carbon bond, and a mechanism for CO insertion can be seen in Figure 1 of Appendix A. On the other hand, alkyl migration occurs when the alkyl group migrates, rather than the CO group, and attaches to a CO cis to where the alkyl was before. mechanism for alkyl migration can be seen in Figure 2 of Appendix A. Carbonyl insertion reactions are really alkyl migration reactions, but are called carbonyl insertion reactions because it appears that the CO group is moving between the carbon-metal bond. Carbonyl insertion reactions are important for making catalysts and for hydroformylation. The commercial industry uses catalysis reactions by using the catalytic metal complexes to produce more complex, and more expensive compounds, from simpler compounds. Hydroformylation is a specific catalysis reaction and is a process that is useful for converting terminal alkenes into a variety of other higher order organic products, such as aldehydes. The commercial industry, mostly utilizes cobalt and rhodium-based catalysts. Therefore, one of the goals of this project is to see if an iron catalyst (iron pentacarbonyl) would be reactive enough to undergo the same mechanism. An example mechanism ofhydroformylation using cobalt can be seen in Figure 3 of Appendix A. The overall goal of this project is to observe an alkene transforming into a higher order organic, such as an aldehyde with the mechanism: Fe(CO)s +OH ➔ [HFe(CO)4] +CO ➔ (H2C=CH-R) ➔ H3C-CH2-Fe(CO)4 ➔H3C-CH2-C(=O)-Fe(CO)3 If the species [HFe(CO)4r is produced in the reaction flask, the alkene should isomerize. This isomerization could occur through several different mechanisms and are discussed later. The last reaction for this project ( experiment 12) shows isomerization of 1-hexene into trans-2- hexene, but the production of the aldehyde was not observed