Gram-to-Kilogram Scale-Up Synthesis of 2,2’-Diallylbisphenol through a Microchannel Reactor

A continuous-flow synthetic platform utilizing a microchannel reactor was developed here to realize the gram-to-kilogram scale-up synthesis of 2,2’-diallylbisphenol A (DABPA) via thermal Claisen rearrangement with high efficiency and safety. The optimal reaction temperature of this thermal rearrangement was confirmed firstly by differential scanning calorimetry and then the classical batch synthesis was carried out to find that large quantities of reaction heat were accumulated, which not only promoted the formation of many by-products but also would bring various uncontrollable risks such as bumping. Thus a simple continuous flow synthetic platform was constructed which employed a microchannel as the reactor. The optimal working temperature of this reactor and the flow velocity of the reactant were screened and established. Compared with the conventional batch method, the utilizing of a flow reactor avoided a large amount of reactant staying in the reaction mixture and minimized the accumulation of reaction heat, which not only enhanced the safety of the reaction process but also prevented the formation of many by-products, delivering a practical strategy for the scale-up synthesis of DABPA.