Hydrochloric Acid → Phthalonitrile

Participants

Reaction Conditions

Reaction Steps

To a 100 mL, three-necked flask fitted with a thermometer, a Dean-Stark trap with condenser, and a nitrogen inlet were added bisphenol A (5.00 g, 21.9 mmol), bis(4-fluorophenyl)phenylphosphine oxide (3.49 g, 11.1 mmol), powdered anhydrous K2CO3 (7.55 g, 54.7 mmol), toluene (10 mL), and N,N-dimethylformamide (DMF) (40 mL). The resulting mixture was degassed with argon at ambient temperature and the Dean-Stark trap was filled with toluene. The mixture was refluxed at 135-145° C. under an argon atmosphere for 12 to 18 h or until no more water was observed being collected by azeotropic distillation in the Dean-Stark trap. FTIR spectroscopy was used to confirm and to monitor the formation of the desired oligomeric product. The toluene was then removed by distillation and the reaction mixture was cooled to 50° C. At this time, 4-nitrophthalonitrile (3.87 g, 22.4 mmol) was added in one portion and the reaction mixture was heated at 80° C. for 6-8 h. The mixture was allowed to cool to ambient temperature and poured into 300 mL of a 5% aqueous HCl solution resulting in the formation of a solid. The material was broken up and collected using a Büchner funnel. The white solid was dissolved in chloroform (200 mL) and washed with 200 mL of a 5% aqueous KOH solution, with 200 mL of distilled water until neutral, with 200 mL of a 5% aqueous HCl solution, and finally with 200 mL of water until neutral. The solvent was removed in vacuo and the solid was vacuum dried to yield the 2:1 oligomeric phthalonitrile (9.89 g, 91%). 1H-NMR (300 MHz, CDCl3): δ 7.61-7.52 (m, aromatic-H), 7.43-7.31 (m, aromatic-H), 7.34-7.19 (m, aromatic-H), 7.02-6.92 (m, aromatic-H), 1.75-1.66 (m, CH3). IR [cm−1]: λ3058 (C═CH), 2969 (CH3), 2231 (CN), 1589 (C═C), 1491 (aromatic), 1281 (CH3), 1248 (C—O), 1173 (C—O), 1117, (P═O), 970 (C—O), 834 (aromatic).

Provenance & Evidence