Ethanol → 3,7,11-Trimethyldodeca-2,4-dienoic acid

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Reaction Steps

To 350 ml. of ethanol, 105 ml. of water and 70 ml. of 50% aqueous sodium hydroxide is added 46.5 g. of ethyl 3,7,11-trimethyldodeca-2,4-dienoate (40% cis, trans and 60% trans,trans). The mixture is refluxed for about 19 hours. After cooling, ethanol is removed under reduced pressure and water added followed by extraction with ether to yield 3,7,11-trimethyldodeca-2,4-dienoic acid containing about 58% trans,trans isomer. Conversion of the thus-obtained acid to the benzylisothiouronium salt recrystallized from aqueous methanol, and regeneration of the acid with ether-aqueous hydrochloric acid provides crystalline trans,trans 3,7,11-trimethyldodeca-2,4-dienoic acid.

Provenance & Evidence