Spectral data was in accordance with the literature. To isolate 6-allyl-6-azabicyclohex-3-en-2-ol ( 2a), 1360 mL of collected water corresponding to the period of 4 to 19 h of irradiation, was evaporated under vacuum and the obtained solid was dissolved in dichloromethane (3 × 250 mL), stirred for 15 min, and filtered. Samples were collected at selected times, concentrated under vacuum and analyzed by 1H NMR (D 2O). A 3150 mL of an aqueous solution of 1a (20 mM) and potassium carbonate (1.2 molar equiv.) was pumped (0.12 mL/min flow rate). Then, the pump was set to 3 rpm (0.12 mL/min flow rate) and the irradiation was turned on. ![]() To fill the PQT6, a 350 mL of an aqueous solution of 1a (20 mM) and potassium carbonate (1.2 molar equiv.) was pumped using the multichannel cassette pumps Watson Marlow 205S (12 silicon tubes 1 × 3 mm). The PQT6 reactor consisting of 12 QT6 tubes was placed inside the home-made UV reactor. General Procedure for Continuous-Flow Photochemical Transformation of 1a to 2a ![]() The reactors were designed for higher scale production of 2a via photochemical irradiation of 1a ( Scheme 2 and Figure 2).ģ.4. To overcome these limitations, herein is presented the development of a home-made UV reactor and a PQT reactor capable of operating under continuous-flow. Such limitation has so far prevented the use of PQT4 reactor in a continuous process. Despite these outstanding productivity results, the PQT4 reactor presents some drawbacks as a consequence of its design, such as a large dead-volume, resulting from the connections between the different quartz tubes ( Figure 1b). Furthermore, regarding the isolated 6-allyl-6-azabicyclohex-3-en-2-ol, ( 2a) ( Scheme 2) and 6-butyl-6-azabicyclohex-3-en-2-ol ( 2b), this reactor was capable of producing 40.9 mg h −1 and 87.0 mg h −1, respectively, as highlighted by Snieckus, V. ![]() Under recirculating conditions, PQT4 gave the best productivity results for both bicyclic aziridines. The reactors were assessed for the photoflow transformation of 1-allyl and 1-n-butylpyridinium salts to the correspondent bicyclic aziridines, under recirculating (FEP4, PTQ4 and PTQ2) and continuous-flow conditions (FEP4). ( b) Parallel quartz tube reactor (PQT4), (left) and top-view under irradiation (right). ( a) FEP4 reactor around metal grid (left), and top-view under irradiation (right). Previously reported home-made continuous-flow reactors.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |