|
RAFT Polymerisation in Continuous Flow Microreactors
Simon Saubern, , CSIRO
Reversible Addition Fragmentation Chain Transfer (RAFT) polymerization has been extensively explored by academic and industry researchers due its ability to control the molecular weights, compositions and architectures of the resulting polymers. We report here on automating the polymerization process with flow chemistry techniques by using in-line degassers to remove oxygen that otherwise would quench the free-radical reaction, and the effects of reactor geometry on the polymerization process.
RAFT Polymer End-group Removal in Continuous Flow Microreactors
Simon Saubern, , CSIRO
Reversible Addition Fragmentation chain Transfer (RAFT) polymerization is favoured due its ability to control the molecular weights, compositions and architectures of polymers.
The thiocarbonylthio groups (RAFT end groups) are retained in the polymer product, leading to coloured polymers ranging from violet and red, through to yellow.
RAFT end group removal following polymerization is desirable, and a multitude of different processes have been outlined over the past years.
Here we demonstrate the effectiveness of a radical induced end-group removal using flow chemistry techniques. Hypophosphite was chosen as a cheap solution that is free of toxic metals like Sn.
The process works in organic solvents or water, providing polymer product equivalent to the batch process.
Synthesis of furanics and levulinic acid from simple carbohydrates via biphasic continuous flow processing
Simon Saubern, , CSIRO
Conversion of sugars under biphasic continuous flow conditions into CMF, HMF and LA is efficient and practicable. A reaction time of 60s is sufficient to produce CMF with 81% isolated yield from D-fructose and 58% yield from sucrose. Yields from batch processes are higher (82% from glucose and 91% from sucrose), but reaction times of ~3h are needed, and the amount of solvent used is about 30 times higher in batch processing.
A Non-Resonant Microwave Applicator for Continuous Flow Chemistry: Safe, Fast Optimization and Scale-Out Synthesis
Ashkan Fardost, Student, Uppsala University
The prospect of a microwave applicator fully dedicated to continuous flow chemistry may offer many advantages over traditional heating methods, such as fast and controlled heating at high temperatures, as well as a higher level of safety regarding explosive reagents and pressure-producing reactions. Synthetic protocols are hereby developed with a unique system utilizing a nonresonant microwave heating applicator purpose-built for continuous flow that heats an entire reactor without pronounced hot and cold spots, allowing method optimization in small scale and subsequent scale-out without scale-up translation. With a pressure resistance of up to 50 bars and volumes spanning the range of 160 µL (1 mm ID) to 6 mL (6 mm ID), the consumable glass reactors employed by the system allow a variety of flow regimes, scales, as well as superheating of solvents. The technology is demonstrated with method optimization and scale-out of classic organic reactions including palladium-catalyzed organic transformations, synthesis of a bioactive M. tuberculosis proteasome inhibitor, and Fischer indole synthesis with a residence time of only 20 seconds, producing 34 grams of compound per hour (199 mmol/hour) with an isolated yield of 85%.
Recycled Gas Flow Control to Optimize Reaction Conversion and the Accomplishment of Heat Integration in Benzene Production through Hydrodealkylation of Toluene
Afshin Abrishamkar, Master student, Lappeenranta University of Technology
Benzene is largely used as an intermediate substance consumed in the production of chemicals, mainly ethylbenzene, cumene, and cyclohexane. In this work, a benzene production plant through hydrodealkylation process was investigated through a simulation by Aspen Plus V7.2® and run based on the real data obtained from a benzene production plant operating in the United States. The reaction takes place in a double-bed catalytic reactor which was assumed as two stoichiometric reactors in the simulation, each represents one compartment. The reaction conversion is decreased at high temperature; therefore, the reactor temperature was controlled by specifying the flow of required recycle gas which enters in between of two reactor beds. The study was enriched with the improvement of thermal efficiency of the plant by heat integration. For this purpose, a heat exchanger network (HEN) was designed to reduce the utility consumption. Furthermore, the part of recycle gas flow was suggested to utilize as the fuel to the furnace. Such gas flow control allows supplying around 70% of the heat required for increasing the reactor feed temperature to the desire point. As the result, the overall efficiency of the plant is increased by the manipulations of gas flows in the process.
|
