The effect of residual group, RR on the reaction rate of transferable group, RT in the alkyl coupling of mixed cuprates, RRRTCuMgBr

• Published in: Reaction kinetics, mechanisms and catalysis mechanisms and catalysis, 2013-04, Vol.108 (2), p.293-304
• Main Authors: Erdik, Ender, Özkan, Duygu
• Format: Article
• Language: English
• Subjects: Bonding strength; BROMIDES; Catalysis; Chemistry; Chemistry and Materials Science; Constants; COPPER OXIDE; Correlation; Cuprates; Industrial Chemistry/Chemical Engineering; JOINING; KINETICS; Physical Chemistry; Reaction kinetics
• ISSN: 1878-5190; 1878-5204
• DOI: 10.1007/s11144-012-0531-4

For the investigation of the effect of residual group, R R on the transfer rate of transferable group, R T in mixed diorganocuprates, R R R T CuMgBr, a detailed direct kinetic study has been carried out and the reaction rates of the transferable group, n -Bu in mixed n -butyl(substituted phenyl)cuprates, n -Bu(FG-C 6 H 4 )CuMgBr in their reactions with n -pentyl bromide in THF at 25 °C have been compared. A second order substitution reaction was found, which is first order with respect to both the cuprate and the alkyl electrophile. The correlation of the n -Bu group transfer rate to the Hammett substituent constants gave a positive reaction constant (ρ) and an evaluation depending on the reaction mechanism was given for the unexpected sign of the reaction constant of Hammett plot. This study provides a kinetic support for the commonly accepted hypothesis regarding the dependence of the R T group transfer ability on the strength of R R -Cu bond in reactions R R R T CuMgBr reagents.