Selective estragole to trans-anethole isomerization in ionic liquids

Trans-anethole is a naturally-occurring product which has been traditionally extracted from anise or fennel oils, albeit with variable proportions of its cisisomer as an impurity. However, the increasing demand of trans-anethole has made extraction from natural sources not sufficient to supply the market, hence the need to produce it synthetically. Effectively, only trans-anethole is interesting for industry since the cis-isomer presents a higher toxicity and unpleasant organoleptic properties. Consequently, the search for efficient and selective catalytic systems able to promote the estragole to trans-anethole isomerization still remains a challenge for synthetic chemists.