A One-step Production of Monoterpene Aocohol Using Supercritical Water in the Absence of Catalyst

A one-step synthesis of monoterpene alcohols such as lavandulol, linalool and geraniol/nerol from hemiterpene alcohols proceeds efficiently in supercritical water (scH2O) without any catalyst. Our device of a microreaction (μ-reaction) system achieves the production of lavandulol in 82% selectivity and 59% yield, respectively, even at a short reaction time of 7.7 s at 30 MPa and 375 in the near-critical region. The yield was superior to conventional method promoted by organometallic catalysts in which the reaction time of 7.25 hours is needed to obtain 54 % yield. When the reaction was carried out at a lower temperature of 300 in hot water, we obtained only 15 % yield even at a reaction time of 38 s. The acidic ability of H2O peculiar to supercritical conditions is thus considered to promote the desired pathway alone, and so the scH2O μ-reaction system could conveniently prevent side reactions such as dehydration and hydrolysis.