NOVELTY - Absolute ethanol is added to (2E,6E)-farnesyl chloride (II), sodium ethoxide is added, cooled, ethyl acetoacetate is dripped in the resulting mixture, and reacted. Purified water is added to the resulting mixture, extracted with n-hexane, organic phase is washed with purified water and 5% saline, dried using anhydrous magnesium sulfate, filtered, and solvent is removed under reduced pressure to obtain (5E,9E)-ethoxycarbonyl ethylfarnesyl acetone (III). (5E,9E)-Ethoxycarbonyl ethylfarnesyl acetone (III) is processed to obtain (5E,9E)-farnesyl acetone (IV).    USE - Preparation of (5E,9E)-farnesyl acetone (claimed).    ADVANTAGE - The method provides (5E,9E)-farnesyl acetone with high yield and high purity without toxicity, under mild reaction conditions, by simple and economical process.    DETAILED DESCRIPTION - (2E,6E)-farnesyl alcohol of formula (I) is added to 1-1.5 times the amount of (2E,6E)-farnesyl triethylamine dissolved in dimethylformamide solution of lithium chloride, cooled to (-10)-0 degrees C, methanesulfonyl chloride is added for 10 minutes, and reacted at 0 degrees C for 2-6 hours. The resulting mixture is poured to ice water, extracted with hexane, organic phase is combined, washed with 5% aqueous solution of potassium hydrogen sulfate, purified water, 5% aqueous sodium bicarbonate and 5% saline, dried using anhydrous magnesium sulfate, filtered and filtrate is distilled under reduced pressure to obtain pale yellow oily liquid of (2E,6E)-farnesyl chloride of formula (II). Absolute ethanol is added to (2E,6E)-farnesyl chloride (II), sodium ethoxide is added, cooled to 0 degrees C, ethyl acetoacetate is dripped in the resulting mixture, heated at (-5)-5 degrees C for 20 minutes and reacted at room temperature for 2-4 hours. Purified water is added to the resulting mixture, extracted with n-hexane, organic phase is washed with purified water and 5% saline, dried using anhydrous magnesium sulfate, filtered, and solvent is removed under reduced pressure to obtain (5E,9E)-ethoxycarbonyl ethylfarnesyl acetone of formula (III). (5E,9E)-Ethoxycarbonyl ethylfarnesyl acetone (III) is processed to obtain (5E,9E)-farnesyl acetone of formula (IV).