Rate constants, Grignard reagent correlations

To that end, the logarithms of the pseudo-first-order rate constants for reactions of 0.02 M Grignard reagent with 0.25 M benzophenone were plotted against the (corrected) voltage of an anodic process at a current density of /i, = 0.06 A cm ( o.oe) [46]- An approximate linear correlation was obtained for methyl-, ethyl-, isopropyl-, t-butyl-, and benzylmagnesium bromide, which, as the author carefully worded it,... 

Organic bromides fall between iodides and chlorides, the rate-controlling step containing contributions from mass transfer and chemical reaction. Hammett p constants for bromobenzene support any of the last three transition states. In the last of the four papers " rate-structure profiles for the formation of Grignard reagents are shown to correlate, with coefficients between 0.73 and 0.99, with other processes involving the electrochemical and chemical reduction of alkyl halides. 

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