Proton-transfer reactions between 9-alkylfluorene and (9-alkylfluorenyl)lithium in ether

摘要: The rates of proton-transfer reactions between 9-substituted fluorenes and fluorenyllithium have been examined in ether at 25 71/sup 0/C. A high primary isotope effect (k/sup H/k/sup D/ = 9.5) substantial kinetic (1.11 +- 0.04) equilibrium (1.19 effects are observed for fluorene. Surprisingly, intermolecular steric seem to play only a minor role spite the fact that alkyl groups located directly carbon involved proton transfer. barriers endergonic cross (i.e., those involving different anion hydrocarbon) half sum two corresponding identity same hydrocarbon). This leads Bronsted slopes which vary from 0.7 fluorenyl 1.8 9-(tert-butyl)fluorenyl anion. give approximate linear correlations with each other ..delta..pK dominated by an correlates sigma*. substituent correlated relationships show transition states responding ofmore » on equilibria appears absent cross-reaction states. results can be consistent Marcus' theory if steps separate transfer.« less