Bridging the gap: A nested-pipe reactor for slow reactions in continuous flow chemical synthesis

Investigation of process temperature and screw speed on properties of a pharmaceutical solid dispersion using corotating and counter-rotating twin-screw extruders

“…According to Poulesquen and Vergnes, the RTD of an extrusion system can be summarized by three attributes, the minimum exit time, the mean residence time and the variance of the distribution. However, in the case of thermally sensitive materials, it may also be important to look at the third moment of distribution for the purpose of characterizing the skewness, which is often characterized for plug flow reactors and in this case provides a value to describe the asymmetry of the RTD. The primary parameters affecting the mean residence time are the feed rate, screw design and the internal free volume of the extruder.…”

“…Mathematically, the RTD equation is fitted by deconvoluting a modified form of Equation , which is modified to be a summation of each contributor, n = 3 was used for our analysis. The mean residence time is calculated from the first moment of the distribution, and the variance is calculated from the second moment The skewness is calculated to describe the asymmetry of the RTD. …”

Development of a Continuously Operating Process for the Enantioselective Synthesis of a β‐Amino Acid Ester via a Solvent‐Free Chemoenzymatic Reaction Sequence

“…[12] In fact, this is a common problem encountered for slow reactions in continuous flow necessitating several hours reaction time. To circumvent such a problem, a nested-pipe reactor has been presented by Minnich and co-workers with reactor volumes ranging from 0.25-8 L. [13] Dean vortices can be used to circumvent the problem of channel wall effects. [13] Such vortices are generated in a curved pipe by a pressure driven flow of the fluid when the higher velocity stream in the center experiences a greater centripetal force and is hence directed outward.…”

“…To circumvent such a problem, a nested-pipe reactor has been presented by Minnich and co-workers with reactor volumes ranging from 0.25-8 L. [13] Dean vortices can be used to circumvent the problem of channel wall effects. [13] Such vortices are generated in a curved pipe by a pressure driven flow of the fluid when the higher velocity stream in the center experiences a greater centripetal force and is hence directed outward. [14] In Figure 2b, conversion of the azaMichael addition at 140 8C in a coiled steel capillary reactor of varying length is plotted as a function of the flow rate at a constant residence time of t = 4 min.…”

Model-based scale-up and reactor design for solvent-free synthesis of an ionic liquid in a millistructured flow reactor

“…[15][16][17][18] Recently, micro process engineering has been used for synthesis of high-quality ionic liquids with increased spacetime yields and even solvent-free reactor operation. [19][20][21][22][23][24][25] Compared with conventional batch processes, the intensified transfer of heat and mass that occurs in microstructured devices offers two major advantages for solvent-free synthesis: first, the reaction heat of the strongly exothermic alkylation step (reaction enthalpy of approximately 100 kJ mol −1 ) can be rapidly removed. This is crucial because a large and uncontrolled increase in temperature reduces product quality by introducing color.…”