Phenol → 4-Phenoxy-4'-phenylethynylbenzophenone

Participants

Reaction Steps

The phenylethynyl group has several unexpected advantages over the ethynyl based analog. See the Hergenrother and Delfort references supra. When 4-fluoro-4'-phenylethynylbenzophenone was treated with phenol in the presence of an alkali metal base such as potassium carbonate in a polar aprotic solvent at 160° C., the expected 4-phenoxy-4'-phenylethynylbenzophenone was afforded in nearly quantitative yield. However, when 4-ethynyl-4'-fluorobenzophenone was used in the same procedure, the result was a mixture of products with a total yield of 60%. Several variations in the procedure were tried, but the resulting product was not exclusively the expected ethynyl arylene-ether. This indicates that when the phenylethynyl endcapping compound is used to terminate nucleophilic reagents, the reaction proceeds qualitatively to afford the phenylethynyl terminated reactive oligomers exclusively. If the ethynyl adduct is used, a variety of products results.

Provenance & Evidence