Table 1. Catalyst Screening for the Hydrogenative Depolymerization of Resins of Nylon-6a.
| entry | complex (2 mol %) | KOtBu | conversion | amino alcohol selectivity (yield %) | oligoamide detection (monomer/dimer/trimer) | remark |
|---|---|---|---|---|---|---|
| 1 | 1 | 8 mol % | 77% | 24% | yes (3:4:2) | no resins recovered |
| 2 | 2 | 8 mol % | 80% | 26% | yes (3:4:2) | no resins recovered |
| 3 | 3 | 8 mol % | 66% | 16% | yes (3:6:4) | no resins recovered |
| 4 | 4 | 2 mol % | 30% | not detected | yes | resins recovered (broken) |
| 5 | 5 | 2 mol % | 22% | not detected | yes | resins recovered (broken) |
| 6 | 6 | 2 mol % | 0% | not detected | no | resins recovered |
| 7 | 7 | 0 mol % | 0% | not detected | no | resins recovered |
| 8 | 1′ | 0 mol % | 22% | not detected | yes | resins recovered (broken) |
| 9 | 2′ | 0 mol % | 18% | not detected | yes | resins recovered (broken) |
a
Catalytic conditions: nylon-6 (117 mg, 1 mmol relative to the mol wt of the monomer), complex (0.02 mmol), KOtBu (2–9 mg, 0.02–0.08 mmol) as specified, DMSO (2.5 mL), temperature 150 °C, reaction time 48 h, and H2 (70 bar). Conversion is based on the weight of soluble materials after hydrogenation (see the Supporting Information). Monomer means amino alcohol. The ratio of monomer/dimer/trimer has been estimated by the LC-MS. “Resins recovered” means complete recovery of resins with the shape and size intact. “Resins recovered (broken)” means that the resins were broken into small pieces after the reaction.