Quid Pro Flow

How do you get into flow? We trained in flow chemistry during postdoctoral research and are now applying it in new areas: materials chemistry, crystallization, and supramolecular synthesis. Typically, when researchers think of "flow", they are considering predominantly liquid-based organic synthesis; application to other disciplines comes with its own challenges. In this Perspective, we highlight why we use and champion flow technologies in our fields, summarize some of the questions we encounter when discussing entry into flow research, and suggest steps to make the transition into the field, emphasizing that communication and collaboration between disciplines is key.

Reactor performance estimation in microscale flow calorimeter for rapid characterization of exothermic reactions

Abstract

Continuous flow calorimeters are a promising tool in process development and safety engineering, especially for flow chemistry applications to characterize the heat release and kinetic parameters of rapid chemical reactions. In this study, the digital accompaniment of an isoperibolic flow calorimeter for characterization of exothermic reactions is presented. To support experimental planning and evaluation, computational fluid dynamic simulations are carried out for single-phase flow in the microreactor. The residence time distribution is obtained and used for estimation of conversion and temperature profiles along the microreactor channel. This leads to an integration of CFD simulations into the calorimeter’s software-guided workflow reducing the experimental effort regarding the determination of thermokinetic data. The approach is tested for a highly exothermic test reaction, which provides further hints for future investigations.

Article highlights

• Estimation of conversion and temperature profiles within a microscale calorimeter

• Combination of CFD simulations and reactor performance estimation

• Approach was tested for highly oxidation of sodium thiosulfate

• Estimated conversion and temperature profiles are in good agreement with experimental data

Graphical abstract

Measuring Kinetics in Flow Using Isoperibolic Flow Calorimetry

Continuous flow calorimeters are a promising tool in process development and safety engineering, particularly for flow chemistry applications. An isoperibolic flow calorimeter is presented for the characterization of exothermic reactions. The calorimeter is adapted to commercially available plate microreactors made of glass and uses Seebeck elements to quantify the heat of reaction. For automation of calibration procedures and calorimetric measurements, the device is connected to a lab automation system. Reaction enthalpy of exothermic reactions is determined via an energy balance of the entire calorimeter. Characterization of reaction kinetics is carried out via a local balancing of the individual Seebeck elements without changing the experimental setup, while using the previous measurements and additional ones at higher flow rates. The calorimeter and the associated measurement procedures were tested with the oxidation of sodium thiosulfate using hydrogen peroxide. Reaction enthalpy was determined to be 594.3 ± 0.7 kJ mol−1, which is within the range of literature values.

Technological Innovations in Photochemistry for Organic Synthesis: Flow Chemistry, High-Throughput Experimentation, Scale-up, and Photoelectrochemistry

Photoinduced chemical transformations have received in recent years a tremendous amount of attention, providing a plethora of opportunities to synthetic organic chemists. However, performing a photochemical transformation can be quite a challenge because of various issues related to the delivery of photons. These challenges have barred the widespread adoption of photochemical steps in the chemical industry. However, in the past decade, several technological innovations have led to more reproducible, selective, and scalable photoinduced reactions. Herein, we provide a comprehensive overview of these exciting technological advances, including flow chemistry, high-throughput experimentation, reactor design and scale-up, and the combination of photo- and electro-chemistry.

Modern advancements in continuous-flow aided kinetic analysis

Although kinetic analysis has traditionally been conducted in a batch vessel, continuous-flow aided kinetic analysis continues to swell in popularity.

Discovery of unexpectedly complex reaction pathways for the Knorr pyrazole synthesis via transient flow

Kinetic data for the Knorr pyrazole synthesis were acquired using transient flow methods, including a novel reactant stoichiometry ramping method, providing new insights into the mechanism, including autocatalysis and an unexpected intermediate.

Design of dynamic trajectories for efficient and data-rich exploration of flow reaction design spaces

Sinusoidal variations of operative parameters in flow chemistry allows the fast exploration of chemical design spaces through inline measurements of an objective function.

Characterization of reaction enthalpy and kinetics in a microscale flow platform

We report an isothermal flow calorimeter for characterization of reaction enthalpy and kinetics.