The GC-MS Observation of Intermediates in a Stepwise Grignard Addition Reaction.

This article describes a three-hour laboratory experiment for the third-year organic chemistry lab whereby the stable organic intermediates and final product of the Grignard addition of 3 equivalents of phenylmagnesium bromide to diethyl carbonate are observed. A 1-mL aliquot is removed from the reaction at the midpoint of addition and subjected to GC–MS analysis. An interesting mass spectral exercise shows the presence of the intermediates ethyl benzoate and benzophenone as well as the product triphenylmethanol.