Iodine → 1,4-Pentadien-3-ol, 3-methyl-1-(2,6,6-trimethyl-1-cyclohexen-1-yl)-

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1.3 mols of magnesium turnings are placed in a 3 L four-necked flask. 100 ml of tetrahydrofuran (THF) and a iodine crystal are added thereto. 50 ml of a 15% vinyl bromide solution in tetrahydrofuran are added with stirring and under nitrogen atmosphere. The solution immediately decolourizes, while the Grignard starts to form with an exothermic reaction: the mixture is cooled to −30° C. and one mol of beta-ionone dissolved in 500 ml of THF and 950 mL of the above 15% vinyl bromide solution are added at the same time through two dropping tunnels, at such a rate that temperature remains below −15 20° C. After completion of the addition, the cooling bath is removed and the reaction mixture is brought to room temperature. After 2 hours the reaction mixture is poured into 2 ml of ice-water containing 10 g of ammonium chloride under stirring, then is extracted with 700 ml of ethyl acetate. The organic phase is washed twice with 100 ml of 15% sodium chloride aqueous solution and dried over sodium sulfate. Solvent is evaporated off under reduced pressure and the resulting thick oil is distilled under vacuum, collecting 202 g of distillate, consisting of vinyl beta-ionol of purity higher than 95%, as determined by NMR analysis (yield: 87.5%).

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