Table 2.
Screening of reaction conditions using PCDTBT-based polymers 1a-S and 1b-S as starting polymers.
| Starting polymer | Reaction solvent | DMDO [equiv] | Reaction time | Result (analysis by 1H NMR spectroscopy, also see Figures 3, 4) |
|---|---|---|---|---|
| 1a-S | CH2Cl2 | 2.5 | 1.5 h | Precipitation of the polymer upon oxidation, byproduct peaks at 9.17 and 8.55 ppm |
| 1a-S | Chlorobenzene | 0.5 | 1.0 h | Partial oxidation to SO, no formation of SO2 |
| 1a-S | Chlorobenzene | 1.0 | 1.0 h | Complete and selective oxidation to 1a-SO, no formation of SO2 |
| 1a-S | Chlorobenzene | 1.5 | 1.0 h | SO2:SO ratio: approx.1:1, no byproduct signal |
| 1a-S | Chlorobenzene | 2.0 | 1.0 h | Incomplete oxidation to SO2 (SO2:SO ratio: 9:1) |
| 1a-S | Chlorobenzene | 2.5 | 1.0 h | Complete oxidation to 1a-SO2, very small byproduct peak at 9.17 ppm, high selectivity |
| 1a-S | Chlorobenzene | 3.0 | 24 h | Complete oxidation to SO2, but byproduct peaks at 9.17 and 8.55 ppm |
| 1b-S | Chlorobenzene | 1.0 | 1.0 h | Formation of SO, also some SO2 |
| 1b-S | Chlorobenzene | 2.0 | 1.0 h | Considerable formation of SO2, S still present |
| 1b-S | Chlorobenzene | 3.0 | 1.0 h | Formation of some neighboring SO2, no more S |
| 1b-S | Chlorobenzene | 4.5 | 1.0 h | Complete oxidation to 1b-SO2 |
Final conditions for the synthesis of 1a-SO, 1a-SO2, and 1b-SO2 highlighted in gray. Reaction procedure: DMDO in acetone (0.074 M) added to stirred polymer solutions (concentration of repeat unit: 0.01 M) at room temperature. Work-up: evaporation of solvents (and excessive DMDO) under reduced pressure at 50°C.