Advantages of a continuous flow microreactor over a standard glass apparatus: The synthesis of trans-1,2-cyclohexanediol, cycloheptene, and naphthvalene

Synthetic organic chemists, unlike chemical engineers, do not typically consider using a continuous flow microreactor as one of their tools in the lab. The preparation of starting materials is often a tedious job and can benefit a lot from a continuous flow operation. Advantages include a faster reaction rate, better control of reaction temperature, improved reproducibility, reduction of the amount of waste, easy scale-up, high yield, and higher purity final product. This paper discusses scope and limitations of using a simple microreactor assembled from 1 or 2 syringe pumps, off-the-shelf poly(tetrafluoroethylene) tubing and HPLC mixers. Examples include the synthesis of trans-1,2-cyclohexanediol from cyclohexene, cycloheptene by dehydration of cycloheptanol, and naphthvalene by the reaction of indene with BuLi and CH₂Cl₂. The results in a continuous flow microreactor are then compared to the more commonly used techniques employing standard glassware (round bottom flask, addition funnel, condenser, etc).