[CH3:1][O:2][CH2:3][C:4]([CH3:18])=[CH:5][CH2:6][CH2:7][C:8]([CH3:17])=[CH:9][CH2:10][CH2:11][C:12]([CH3:16])(O)[CH:13]=[CH2:14].O.COCC(C)=CCCC(C)=CCC=C(C)C=C>CCOCC.O.O.O.O.O.S([O-])([O-])(=O)=O.[Cu+2]>[CH3:1][O:2][CH2:3][C:4]([CH3:18])=[CH:5][CH2:6][CH2:7][C:8]([CH3:17])=[CH:9][CH2:10][CH2:11][C:12](=[CH2:16])[CH:13]=[CH2:14]5 g of copper sulfate pentahydrate are suspended in 20 g of paraffin oil, with vigorous stirring, and the suspension is heated at 180° C under 20 mm Hg. The water of crystallization which is eliminated is removed through a descending condenser. After the reaction has ended, 25 g (0.1 mole) of 12-methoxy-3,7,11-trimethyl-dodeca-1,6,10-trien-3-ol are added dropwise to the suspension and water and reaction product are distilled off simultaneously (reaction time about 30 minutes). After completion, the distillate is taken up in 100 ml of ether, the ether solution is washed with sodium carbonate solution, then washed neutral with water and dried over sodium sulfate, and the drying agent is then filtered off. After distilling off the ether, the product which remains is fractionated, giving 11 g of a 2:1 mixture of 12-methoxy-3,7,11-trimethyl-dodeca-1,3,6,10-tetraene and 12-methoxy-3-methylene-7,11-dimethyl-dodeca-1,6,10- -triene (yield 47%).
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