3-Methylbenzaldehyde → m-Ethylbenzaldehyde

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Reaction Steps

116.5 Gm. of 1,5-diazabicyclo[3.4.0]nonene-5 is added to 107.5 gm. of m-tolualdehyde and 400 gm. of o-carbomethoxybenzyltriphenylphosphonium bromide in 2000 ml. of acetonitrile. The mixture is refluxed briefly then cooled and the solvent removed under vacuum. The residue is dissolved in chloroform and washed with dilute hydrochloric acid, and the solution dried and evaporated. The product is refluxed for 11 hours in a solution of 111 gm. potassium hydroxide in 1000 ml. of water and 150 ml. of methanol. The solution is cooled and extracted with chloroform. The aqueous solution is acidified with concentrated hydrochloric acid and extracted with chloroform. The extract is dried and evaporated to give 177.5 gm. (91%) of 3'-methylstilbene-2-carboxylic acid (ca. 60:40 cis:trans). Use of m-ethylbenzaldehyde instead of m-tolualdehyde gives a similar yield of 3'-ethylstilbene-2-carboxylic acid.

Provenance & Evidence