Dehydrocinnamaldehyd-diethylacetal

synthetischeTo a flask equipped with a 12-in. Vigreux column and distillation head is added 74.0 gm (0.50 mole) of triethyl orthoformate, 51.0 gm (0.50 mole)of phenylacetylene, and 3.0 gm of zinc iodide* catalyst. The flask must first be heated to 135°C before ethanol starts to reflux. The ethanol distillate (26.4 gm) boiling at 65°-88°C is removed over a period of 1 hr while the temperature of the reaction mixture is raised to 200°-210°C. The reaction mixture is cooled and filtered, the precipitate washed with 5 ml of ether and the ether combined with the filtrate is distilled to afford 73-80 gm (72-78%), b.p. 99-100°C (2.0 mm Hg). The IR spectrum showed absorption at 4.5-μ (—C=C—) and 9.0-μ region ( - C — O ).