A Scalable Zinc Activation Procedure Using DIBAL-H in a Reformatsky Reaction

The highly exothermic nature of Reformatsky reagent formation and the reported unpredictability of the induction time for its formation pose challenging problems for scaling up Reformatsky reactions. A zinc-activation procedure using DIBAL-H was developed and investigated using reaction calorimetry along with subsequent parts of the process. This procedure was shown to have important advantages for scale-up relative to previous zinc activation methods, including an immediate start of Reformatsky reagent formation with addition-controlled reaction. Calorimetric analysis was especially useful in specifying quickly a suitable temperature for Reformatsky reagent formation. The process was scaled up successfully.