Photo isomerization of cis‐cyclooctene to trans‐cyclooctene: Integration of a micro‐flow reactor and separation by specific adsorption

Abstract

Liquid-phase adsorption has hardly been established in micro-flow, although this constitutes an industrially vital method for product separation. A micro-flow UV-photo isomerization process converts cis-cyclooctene partly into trans-cyclooctene, leaving an isomeric mixture. Trans-cyclooctene adsorption and thus separation was achieved in a fixed-bed micro-flow reactor, packed with AgNO 3 /SiO 2 powder, while the cis-isomer stays in the flow. The closed-loop recycling-flow has been presented as systemic approach to enrich the trans-cyclooctene from its cis-isomer. Inflow adsorption in recycling-mode has hardly been reported so that a full theoretical study has been conducted. This insight is used to evaluate three process design options to reach an optimum yield of trans-cyclooctene. These differ firstly in the variation of the individual residence times in the reactor and separator, the additional process option of refreshing the adsorption column under use, and the periodicity of the recycle flow.

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

“…383 The trans-for-cis photoisomerization step was performed in two microflow reactors placed in parallel and saturation of the packed beds was avoided by switching between beds (after 30−90 min), allowing the process to be run continuously. The two-step photoisomerization and adsorption process was later optimized through a combined experimental and theoretical effort, 384 resulting in 90% transfor-cis conversion after 3 h recirculation time. Using this method, new TCO derivatives with 18 F-labeled polyethylene glycol chains were synthesized for pretargeting PET imaging studies.…”

Pentafulvene–Maleimide Cycloaddition for Bioorthogonal Ligation

“…To investigate the reaction between fulvenes and maleimides in purely aqueous systems, we initially prepared the ethoxyethanol pentafulvene 1a (Figures S1–S6 in the Supporting Information) from 4-(2,4-cyclopentadien-1-ylidene) pentanoic acid 1b to enhance its solubility. In contrast to other bioconjugation regents that require more stringent storage at −20 °C, , the pentafulvene 1a was found to have good stability with no degradation detected upon bulk storage at 23 °C for 14 days and −20 °C for >18 months, or as an aqueous solution for >48 h. Facile, efficient, and multigram preparation (2 steps; >80%) of pentafulvene 1a from cheap and common reagents also offers a unique advantage over other bioconjugation reagents that require complex multistep synthetic strategies or specialized processes. − …”

Enhanced flow synthesis of small molecules by in-line integration of sequential catalysis and benchtop twin-column continuous chromatography

“…Considering the operating linear velocity of 300 cm h −1 , the saturation time corresponding to the 1% BT was 61.5 min. 17 This means that, reached this loading volume, the product starts being lost in the eluate, with no more adsorption on the resin, compromising the yield of the process. This was then considered as the reference loading for a batch single-column chromatography in order to avoid sacrificing the yield of the product.…”