Green Chemistry in Oscillatory Baffled Reactors - Process Intensification for Green Chemistry - page 168

Figure 5.11 Rapid screening of residence times in an imine synthesis using a meso-OBR.
Reprinted from Mohd Rasdi et al # 2012, with permission from Elsevier.

This new scale of operation has opened up a number of new applications for OBRs as
devices for the green chemist. They allow process development with minimal use of
reactants and minimal creation of waste. A recent study has demonstrated the following
advantages for a screening/kinetic study of an imine formation reaction [12]:
A 75% reduction in the amount of reagent required.
A 50% reduction in process development time (versus conventional screening using
batch stirred beakers).
The rate constant data gathered from the mesoscale system is more reproducible, with a

20% decrease in the standard deviation.

Figure 5.11 illustrates rapid screening of the imine synthesis for residence time, in a step-
by-step fashion. This can also be achieved by dynamically altering variables. The
concentration is monitored by online infrared (IR).

5.2.3.1 Green Chemistry Elements
This case study illustrates the following green chemistry principles:

(1) Prevention: Process development in these reactors should facilitate the development
of more efficient, less wasteful processes in the laboratory. It is often the case that
process inefficiencies begin in the laboratory when processes are developed in
beakers and so on.
(2) Atom Economy: As Point 1.
(3) Less Hazardous Chemical Synthesis: Again, laboratory-scale flow reactors are
valuable tools in investigating process options for reducing chemical hazards within
processes.