Recently visible light used organic reaction is attractive area for me. Because it can make difficult bond in short steps under mild reaction conditions.
But scale up is difficult because key factor of photo reaction is light. It means photo absorbance is important and so it is difficult to scale up. One approach is Plug Flow Reactor. It can increase illumination of the reaction solution by increasing surface-area-to volume ratio. But kilo gram scale up is still difficult.
Today I read an exciting article to overcome the issue. The article is published from researcher of AbbVie.
They proposed to use high intensity lasers for light source and Continuously stirred-tank reactor(CSTR) with Beam Expander. From freely available supporting information, reactor looks like below.
They optimized reaction condition and succeeded to conduct 1.54kg synthesis of substituted benzene derivative with C-N cross coupling in 100ml CSTR. It took only 32h!
CSTR has advantage for solid handling compared to flow reactor. I think this reactor is interesting and attractive for large scale photo chemical reaction.
It is worth to know that big pharma try to develop not only drug but also science and technology I think.