Mongin, Florence; Curty, Christophe; Marzi, Elena; Leroux, Frederic R.; Schlosser, Manfred published an article in 2015, the title of the article was Substituent effects on the relative rates and free energies of ortho-lithiation reactions: families of fluorobenzenes as the substrates.Category: ethers-buliding-blocks And the article contains the following content:
2-, 3- And 4-substituted fluorobenzenes and 5-substituted 1,3-difluorobenzenes were metalated with sec-butyllithium (LIS) and with lithium 2,2,6,6-tetramethylpiperidide (LiTMP) under irreversible conditions in order to determine the rates of reaction relative to the unsubstituted parent compounds (fluorobenzene and 1,3-difluorobenzene). In addition, the pairs of resulting aryllithiums were subjected to acid-base equilibration to furnish the thermodn. stabilities (or: basicities) of these species again relative to the parent compounds Not surprisingly, the effect diminishes with the distance of a given substituent to the lithiation center (ortho > meta > para) and it reaches its maximum at the ground state equilibration of the organometallic intermediate whereas it fades away at transition states, in particular reactant-like ones. Fluorine, the most powerful activator in the entire series if located at an ortho position, increases the rates of LIS- and LiTMP-promoted metalations by resp. 2 and 3 powers of ten, but by 7 to 8 powers of ten the aryllithium equilibrium stability. The experimental process involved the reaction of 1-Fluoro-2-methoxybenzene(cas: 321-28-8).Category: ethers-buliding-blocks
The Article related to fluorobenzene lithiation substituent effect kinetics equilibrium, Physical Organic Chemistry: Addition, Elimination, and Substitution Reactions and other aspects.Category: ethers-buliding-blocks
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