Pairing Synchrotron Radiation with an ATR-Integrated Microreactor for In-Situ Spatiotemporal Characterization of Chemical Reactions

Abstract

Microfluidic devices consist of microfabricated structures designed to control minuscule volumes of fluid with exceptional precision. The growth of this field has allowed researchers to miniaturize lab-based processes, providing an alternative experimental approach which is more efficient, safer, eco-friendly, and cost-effective. In-situ monitoring of chemical reactions is greatly important to the field of chemistry. Real-time characterization allows for a better understanding of the system by investigating the underlying mechanisms and reaction kinetics. Fourier-transformed infrared (FTIR) spectroscopy is a suitable technique to be coupled with microfluidics as it is non-invasive, straightforward, reliable, and sensitive to molecular changes which occur during a reaction. With the use of attenuated total reflection (ATR) FTIR spectroscopy, significant attenuation of radiation by the fluidic environment is overcome. The quantitative capabilities of IR spectroscopy coupled with a microfluidic device provide researchers with the ability to monitor reaction variables such as reagent concentrations in-situ. In this thesis, I evaluate the abilities of a unique microfluidic device equipped with a single-bounce ATR element by monitoring a proof-of-concept chemical reaction using synchrotron sourced IR radiation. The unique capabilities of the Mid-IR beamlines’ horizontal ATR (hATR) endstation at the Canadian Light Source (CLS) allow the beam spot to be positioned at any point along the length of the channel to assess the chemical environment at many different reaction times. Coupling the endstation capabilities with the single-bounce ATR accessory and synchrotron radiation allows different sensing areas to be individually addressed, thereby providing the ability to obtain spatially and temporally resolved information. This microreactor provided in-situ characterization, which was used to spatially and temporally track the concentration changes throughout an SN2 reaction. The collected measurements were then used to determine the kinetic rate constant of the monitored reaction. Therefore, this thesis successfully demonstrates the microreactors’ impressive capabilities to monitor a reaction and extract kinetic parameters