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Title: | Synthesis of N,N '-dialkyl-6,6 '-dibromoisoindigo Derivatives by Continuous Flow | Authors: | MAES, Veronique PIROTTE, Geert BREBELS, Jeroen VERSTAPPEN, Pieter LUTSEN, Laurence VANDERZANDE, Dirk MAES, Wouter |
Issue Date: | 2015 | Publisher: | AKADEMIAI KIADO RT | Source: | JOURNAL OF FLOW CHEMISTRY, 5 (4), p. 201-209 | Abstract: | In this work, the synthesis of N,N'-dialkyl-6,6'-dibromoisoindigo derivatives by continuous-flow chemistry is explored as a means to enhance material availability and structural diversity, in particular toward the application of isoindigo-based semiconductors in high-performance organic photovoltaic devices. The individual steps in the conventional batch synthesis protocol are evaluated and, when needed, adapted to flow reactors. To overcome the low solubility of non-alkylated 6,6'-dibromoisoindigo in common organic solvents, the flow condensation reaction between the 6-bromo-isatin and 6-bromo-oxindole precursors is evaluated in polar aprotic solvents. Dialkylation of 6,6'-dibromoisoindigo is readily performed in flow using a solid-phase reactor packed with potassium carbonate. In an alternative strategy, solubility is ensured by first introducing the N-alkyl side chains on 6-bromo-isatin and 6-bromo-oxindole (accessible via a high-yielding flow reduction of alkylated 6-bromo-isatin), followed by condensation using the conventional method in acetic-hydrochloric acid medium. The N, N'-dialkylated 6,6'-dibromoisoindigo derivatives indeed show enhanced solubility in the hot reaction mixture compared to the non-alkylated material but eventually precipitate when the reaction mixture is cooled down. Nevertheless, the condensation between both alkylated starting materials is achieved in flow without any blockages by keeping the outlet from the reactor heated and as short as possible. The latter strategy allows the preparation of both symmetrically and asymmetrically N-substituted isoindigo compounds. | Notes: | [Maes, Veronique; Pirotte, Geert; Brebels, Jeroen; Verstappen, Pieter; Vanderzande, Dirk; Maes, Wouter] Hasselt Univ, Inst Mat Res IMO IMOMEC, DSOS, Agoralaan 1,Bldg D, B-3590 Diepenbeek, Belgium. [Maes, Veronique; Pirotte, Geert; Brebels, Jeroen; Verstappen, Pieter; Lutsen, Laurence; Vanderzande, Dirk; Maes, Wouter] IMEC IMOMEC, B-3590 Diepenbeek, Belgium. | Keywords: | isoindigo; N-alkylation; condensation; reduction; asymmetric substitution; organic photovoltaics;isoindigo; N-alkylation; condensation; reduction; asymmetric substitution; organic photovoltaics | Document URI: | http://hdl.handle.net/1942/21676 | ISSN: | 2062-249X | e-ISSN: | 2063-0212 | DOI: | 10.1556/1846.2015.00033 | ISI #: | 000368600700003 | Rights: | © 2015 Akadémiai Kiadó | Category: | A1 | Type: | Journal Contribution | Validations: | ecoom 2017 |
Appears in Collections: | Research publications |
Files in This Item:
File | Description | Size | Format | |
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Maes, J Flow Chem 2015, 201 (1).pdf Restricted Access | Published version | 445.63 kB | Adobe PDF | View/Open Request a copy |
Isoindigo in flow Maes et al revised manuscript.docx | Peer-reviewed author version | 267.75 kB | Microsoft Word | View/Open |
Revised SI isoindigo in flow Maes et al.pdf Restricted Access | Supplementary material | 1.4 MB | Adobe PDF | View/Open Request a copy |
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