TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The water immiscible, non-halogenated organic solvent is hexane (preferred), ethyl acetate, diethyl ether and/or petroleum ether. The inorganic base is sodium bicarbonate (preferred), lithium hydroxide, potassium hydroxide, sodium carbonate, lithium carbonate and/or potassium bicarbonate. The concentration of amount of (C) dissolved in water immiscible, non halogenated organic solvent is 2-20 wt./vol.%. The concentration of inorganic base is 0.05-10 wt./vol.%.Preferred Method: In the method, (D) is stirred at a temperature of 45-55degreesC. The method further comprises acidifying the aqueous phase to a pH of 4.5 by adding hydrochloride solution (2N) to aqueous phase. ACTIVITY - Insect Repellent.    MECHANISM OF ACTION - None given.    EXAMPLE - Vacuum distilled catnip (10 g) contained nepetalactone isomers dissolved in hexane (2-20 wt./vol.) was added in a flask. The solution was vigorously stirred and aqueous solution of sodium bicarbonate (0.05-10 wt./vol.%) was added at 50degreesC, stirred for 32 hours and the aqueous phase was separated every 8 hours and recharged with equivalent amount of aqueous base. The organic layer was separated from the basic aqueous phase and rinsed with water, then twice rinsed with saturated sodium bicarbonate solution (sodium bicarbonate (10 g) was added distilled water (100 ml)) and finally with saturated sodium chloride (sodium chloride (25 g) was added to distilled water (100 ml)) and worked up to give EZ-nepetalactone (4.2 g). Combined aqueous phases were extracted with non-halogenated organic phase and acidified to pH 4.5. The separated oil was extracted with ethyl acetate in three portions. Combined ethyl acetate fractions were then washed with saturated sodium chloride. The obtained mixture was then dried with magnesium sulfate, filtered to give ZE-nepetalic acid. The ZE-acid was dissolved in toluene and azeotropically lactonized to produce ZE-nepetalactone in the presence of p-toluene sulfonic acid. Azeotropic dehydration was carried out. Toluene was stripped by distillation to give ZE-nepetalactone (5.1 g) and the mixture of (4aS, 7S, 7aR)- and (4aS, 7S, 7aS)-nepetalactones (10 g) were separated.