Phenylpropiolic acid

WHITE TO SLIGHTLY BEIGE FINE CRYSTALLINE POWDER

Phenylpropiolic Acid is used as a reagent in the high yield synthesis of 3,3-diphenylpropanoic acid derivatives via hydrophenylation and ionic hydrogenation with strong Lewis acids. It is also used in the synthesis of highly substituted aromatic rings via the alkyne-mediated approach which serve as templates for drug design.

ChEBI: An acetylenic compound that is propynoic acid in which the acetylenic hydrogen is replaced by a phenyl group.

Add phenylacetylene 6 mmol and ultra-dry tetrahydrofuran 25-30 mL in a 100 mL reaction flask, followed by evacuation treatment, N2 protection, put the reaction flask into an ethanol solution at -78C, and then continue to add n-butyllithium 6 mmol, and after 1-1.5 h of reaction, access to a carbon dioxide balloon (inserted into the liquid level), and after 3-4 h of reaction, change the carbon dioxide balloon once again After 3-4 h of reaction, the reaction was replaced with another carbon dioxide balloon, and the reaction was carried out overnight. Afterwards, the reaction bottle was removed and stirred at room temperature to room temperature, 20mL of saturated ammonium chloride solution was added to the reaction bottle, and stirring was continued for 20-30 minutes. At the end of the reaction, it was first extracted with ether (220mL), and the aqueous phase was taken and the pH was adjusted to about 3 with dilute hydrochloric acid, and then ethyl acetate (220mL) was used, and the product phenylpropiolic acid was obtained by spin-drying at low pressure.

Crystallise the acid from *benzene, CCl4 (m 136o) or aqueous EtOH. The S-benzylisothiuronium salt has m 184-186o (from EtOH). [Beilstein 9 II 436, 9 III 3061, 9 IV 2327.]