p-Toluenesulfonic acid monohydrate → 4-(2,6,6-Trimethylcyclohex-2-en-1-ylidene)but-2-en-2-yl acetate

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Reaction Steps

96 g of β-ionone are dissolved in 500 ml of isopropenyl acetate and treated with 0.6 g of p-toluenesulphonic acid monohydrate. The mixture is stirred at reflux temperature under an inert gas atmosphere for 24 hours. The excess isopropenyl acetate is distilled off from the mixture under a vacuum (temperature ≤50° ) and then the mixture is treated several times with hexane in order to liberate residual amounts of isopropenyl acetate and concentrated again. In this manner, there are obtained 108 g of brown-red 4-(2,6,6-trimethyl-2-cyclohexen-1-ylidene)-2-acetoxy-but-2-ene (formula II; R = acetyl).

Provenance & Evidence