Detailed optimization of polycondensation reaction via direct C-H arylation of ethylenedioxythiophene.

The polycondensation reaction of 3,4-ethylenedioxythiophene with 2,7-dibromo-9,9-dioctylfluorene via Pd-catalyzed direct arylation gives poly[(3,4-ethylenedioxythiophene-2,5-diyl)-(9,9-dioctylfluorene-2,7-diyl)]. The reaction conditions are optimized in terms of the Pd precatalysts, reaction time, and carboxylic acid additives. The combination of 1 mol% Pd(OAc)(2) and 1-adamantanecarboxylic acid as an additive is the optimized catalytic system, and it yields the corresponding polymer with a molecular weight of 39,400 in 89% yield. The polycondensation reaction, followed by an end-capping reaction, effectively provides a linear polymer without Br terminals.