Identifying Homocouplings as Critical Side Reactions in Direct Arylation Polycondensation.
ACS Macro Lett
; 3(8): 819-823, 2014 Aug 19.
Article
em En
| MEDLINE
| ID: mdl-35590707
ABSTRACT
Homocouplings are identified as major side reactions in direct arylation polycondensation (DAP) of 4,7-bis(4-hexyl-2-thienyl)-2,1,3-benzothiadiazole (TBT) and 2,7-dibromo-9-(1-octylnonyl)-9H-carbazole (CbzBr2). Using size exclusion chromatography (SEC) and NMR spectroscopy, we demonstrate that both TBT and Cbz homocouplings occur at a considerable extent. TBT homocoupling preferentially occurs under phosphine-free conditions but can be suppressed in the presence of a phosphine ligand. Cbz homocoupling is temperature-dependent and more prevalent at higher temperatures. By contrast, evidence for chain branching as a result of unselective C-H arylation is not found for this monomer combination. These results emphasize that particular attention has to be paid to homocouplings in direct arylation polycondensations as a major source of main-chain defects, especially under phosphine-free conditions.
Texto completo:
1
Base de dados:
MEDLINE
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article