It’s only fair to share… Diphenhydramine Hydrochloride REGULAR SYNTHESIS FLOW SYNTHESIS Diphenhydramine hydrochloride is the active pharmaceutical ingredient in several widely used medications (e.g., Benadryl, Zzzquil, Tylenol PM, Unisom), and its worldwide demand is higher than 100 tons/year. In 2013, Jamison and co-workers developed a continuous flow process for the synthesis of 3 minimizing waste …