a chromatographic column with silica gel 60 and the following solvent gradient system 100 hexane 8 2 hexane ethyl acetate 7 3 hexane ethyl acetate 6 4 hexane ethyl acetate 100 ethyl acetate and 100 methanol u the organic phase was therefore transferred to a collecting flask and purification under preparative circular chromatography has followed ccp cromatotron v after this procedure the product 6 has been submitted to purity determination by high efficiency liquid chromatography clae finding a purity index gt 95 the product hinokinin was taken for 1 h and 13 c nmr analysis and u03b1 d 26 x reaction between hinokinin and nitric acid in chloroform in microscale we have 50 mg of hinokinin in chloroform by keeping the reaction medium at u2212 6 u00b0 c adding 6 mol eq of nitric acid dropwise and slowly keeping the reaction under the same conditions and with constant shaking for two hours after which a saturated na 2 co 3 solution was added to finish it z isolation of 6 6 u2032 dinitrohinokinine was made by 1 extraction of the reaction medium with chloroform and subsequent evaporation under reduced pressure 2 recrystallizations under methanol aa the organic phase was therefore.