Chemistry in Microstructured Reactors

Abstract

Organic chemistryOrganic chemistry Z 0200 Chemistry in Microstructured Reactors -[292 refs.]. -(JAEHNISCH*, K.; HESSEL, V.; LOEWE, H.; BAERNS, M.; Angew.

The Claisen Rearrangement – Part 2: Impact Factor Analysis of the Claisen Rearrangement, in Batch and in Flow

“…A detailed benefit and potential analysis of microreactors and flow chemistry can be found in many reviews, see [63,[72][73][74]. For the purpose of this paper, it is useful to recall the main benefits in the following.…”

“…For the purpose of this paper, it is useful to recall the main benefits in the following. High surface-to-volume ratios up to 10 000-50 000 m 2 m -3 enable excellent heat and mass transfer rates [72] which constitute the transfer intensification. The heat exchange in microchannels is very efficient.…”

Flow Markers in Microreactors: A Generally Applicable Chromatographic Method for Monitoring Flow Rates During Reactions

“…The interest in using microreactors for synthesis has increased enormously in recent years [1][2][3][4][5][6]. Traditionally, the emphasis has either been on the production of chemicals in microstructured flow reactors, which has several benefits over conventional batch reactions, or on rather specialized and novel reaction processes on a very small scale [7,8].…”

Polimerização em solução desenvolvida em milireatores.

“…In some cases, millisecond mixing times have also been proved. This is faster than most conventional stirrers, which have mixing times from one up to several tens of seconds (JÄNISCH et al, 2004).…”

“…However, the number of monomer molecules reacting in the initiation step is far less than the number in the propagation step for a process producing high polymer; can hence be neglected (ODIAN, 2003): (27) As reported by Odian (2003), since the rate constants for all the propagation steps are the same, the polymerization rate can be expressed by: (28) Radical concentrations are difficult values to obtain, because they are very low; since these concentrations do usually not vary too much throughout the reaction (typical polymerizations achieve a steady-state after a period, which may be at most a minute), the steady state approximation can be assumed for them; this is equivalent to stating that the rates of initiation and termination are equal: (29) can be expressed by: (30) and the rate of polymerization finally becomes: (31) It is interesting to note that doubling the rate of initiation does not double the polymerization rate, but increases it by a factor (ODIAN, 2003).…”