Using Reaction Calorimetry for Safe Process Scale up

Sodium borohydride (NaBH₄) is a versatile reagent used to convert carbonyl groups into alcohols and it can be used in aqueous or alcoholic solutions. It is also known that sodium borohydride reduction is an exothermal reaction with vigorous hydrogen evolution and this can pose a significant problem for scaling-up of bench experiments. Calorimetric information is very useful in helping to identify issues related to heat transfer, fouling, precipitation, viscosity changes. Therefore a hydrogenation study was performed in an OptiMax^TM HFCal instrument using a model carbonyl compound and sodium borohydride in: (a) solid form (powder) and (b) liquid form (12 wt.% aq. solution stabilized with 14 M NaOH). The findings from this study were applied to the safe scale-up of hydrogenation reaction of tetraformyl dimethyl tetraphenylbiphenyl diamine to tetrahydroxy dimethyl tetraphenylbiphenyl diamine.