Method for isolation of catmint oil

Abstract

A high yielding method is described for improved isolation of catmint oil after recovery from catmint plants of the genus Nepeta . Catmint oil can be obtained in quantitative yields for use in insect repellent compositions.

What is claimed is: 
     
         1 . A method for recovering catmint oil from plants of the genus  Nepeta , comprising
 (a) providing a first liquid mixture comprising catmint oil and water;   (b) contacting the first liquid mixture with at least one water-immiscible organic extracting solvent to form a second liquid mixture that contains a solvent phase and an aqueous phase;   (c) in the second liquid mixture, separating the solvent phase from the aqueous phase, and recovering the solvent phase; and   (d) removing the extracting solvent from the solvent phase to isolate the catmint oil.   
     
     
         2 . A method for recovering catmint oil from plants of the genus  Nepeta , comprising
 (a) providing a first liquid mixture comprising catmint oil and water;   (b) in the first liquid mixture, separating catmint oil from water, and recovering the catmint oil;   (c) contacting the catmint oil recovered in (b) with at least one water-immiscible extracting solvent to form a second liquid mixture that contains a solvent phase and an aqueous phase;   (d) in the second liquid mixture, separating the solvent phase from the aqueous phase, and recovering the solvent phase; and   (e) removing the extracting solvent from the solvent phase to isolate the catmint oil.   
     
     
         3 . A method according to  claim 1  or  2  wherein an aqueous phase from which a catmint oil phase has been separated is contacted with at least one water-immiscible extracting solvent, and a catmint oil and extracting solvent phase is separated, the extracting solvent removed, and the catmint oil recovered. 
     
     
         4 . A method according to  claim 1  or  2  wherein the yield of catmint oil is at least about 50% greater than the yield of catmint oil obtained from the separation of catmint oil from water in the absence of an organic extracting solvent. 
     
     
         5 . A method according to  claim 1  or  2  wherein the water immiscible organic extracting solvent has a density that is different from the density of water by at least about 0.1 Wm. 
     
     
         6 . A method according to  claim 5  wherein the water immiscible organic extracting solvent is selected from the group consisting of a hexane, petroleum ether, toluene, a xylene, ethyl acetate, dichloromethane (DCM), chloroform and mixtures thereof. 
     
     
         7 . A method according to  claim 1  or  2  further comprising hydrogenating the recovered catmint oil. 
     
     
         8 . A method according to  claim 7  further comprising formulating the hydrogenated catmint oil in an insect repellent composition.