Olefin Metathesis Custom Design of Industrial Chemical Feedstocks

Olefin Metathesis Custom Design of Industrial Chemical Feedstocks 

The magical-looking olefin metathesis reaction (see chapter 7) has become a mainstay in the petroleum industry and a powerful addition to 

Initially, the most obvious mechanism for olefin metathesis was a land of molecular square dance in which two different olefin molecules join to form a cyclobutane ring and then change partners to form two new olefin molecules. While this thermal reaction is Woodward-Hoffmann forbidden, transition metals were initially perceived to allow violations of these rules. However, no cyclobutanes were detected in olefin metathesis reactions, nor did cyclobutanes produce olefins when placed into metathesis reaction mixtures. The breakthrough came in 1971 when Yves Chauvin (1930- ), at the French Petroleum Institute, made the concepmal link between the Phillips Petroleum reaction discovered in 1964 and metallocarbenes isolated in the same year by Ernest Otto Fischer (see chapter 7). Other important discoveries were made by Michael F. Lappert (1928- ) at Sussex, Charles P. Casey (1942- ) at Wisconsin, and especially Thomas J. Katz (1936- ) at Columbia. The mechanism involves formation of a metallocyclobutane (see the accompanying figure), from reaction of a metallocarbene ( M=CR 2 ) with an olefin (R2C=CR2), that splits into a new olefin (R 2C=CR2) and a new metallocarbene ( M=CR2 ). 

---