Synthesis of 4-hydroxy-4-phenylbut-2-ynoic acid

Preparation of 4-hydroxy-4-phenylbut-2-ynoic acid

58 g of 3-phenylprop-l-yn-3-ol are added during 3 hours to an ethereal solution of ethylmagnesium bromide (from magnesium, 25 g) with efficient stirring and ice-cooling. The colloidal suspension obtained is stirred at 0° C for a further 30 minutes and then poured on to an excess of solid carbon dioxide in an autoclave, which is then sealed. After 22 hours the Grignard complex is decomposed with dilute sulfuric acid; isolation of the acidic fraction gives a 70 g of dark semi-solid mass. Trituration with cold benzene furnishes the 48.5 g of 4-hydroxy-4-phenylbut-2-ynoic acid with m.p. 84-85° C, which may be further purified by crystallization from benzene to m.p. 89-90° C.

Jones, E. R. H., Shen, T. Y.;Whiting, M. C, ibid. (1950) 239

Acetylenic compounds in organic synthesis, by R. R. Alexander, 199, 1955

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