Method of producing farnesyl acetone

A process for preparing keto compounds of the general formula (I)

• where
• R1 is hydrogen or a —C(O)OR3 radical, where
• R3 is C1-C4-alkyl;
• R2 is C1-C4-alkyl;
• X1 and X2 are both hydrogen or together are the second bond of a double bond between the carbon atoms to which they are bound;
• X3 and X4 are both hydrogen or together are the second bond of a double bond between the carbon atoms to which they are bound;
• X5, X6, X7 and X8 are each hydrogen;
• where one of the combinations of the radicals X5 and X7, X6 and X7 or X7 and X8 can also be the second bond of a double bond between the carbon atoms to which they are bound, and isomers and mixtures thereof,
• where
• a) at least one farnesene compound of the general formula (II)
• where
• X1 and X2 together are the second bond of a double bond between the carbon atoms to which they are bound;
• X3 and X4 together are the second bond of a double bond between the carbon atoms to which they are bound;
• X5 and X7 together are the second bond of a double bond between the carbon atoms to which they are bound, with the proviso that X6 is hydrogen;
• or
• X6 and X7 together are the second bond of a double bond between the carbon atoms to which they are bound, with the proviso that X5 is hydrogen, and
• X8 is hydrogen;
• is subjected to a reaction with a β-keto ester of the general formula (III)
• R2—CO—CH2—R1 (III)
• where
• R1 is a —C(O)OR3 radical,
• where R3 is C1-C4-alkyl
• R2 is C1-C4-alkyl;
• in the presence of a catalyst wherein the catalyst is a compound or complex of a transition metal of group 9 of the Periodic Table and a solvent/water mixture, where the reaction mixture is subjected to dispersing using at least one mixer at a Reynolds number of greater than 104,
• to give a compound of the formula (I-a),
• where
• R1 is a —C(O)OR3 radical,
• where R3 is C1-C4-alkyl;
• R2 is C1-C4-alkyl;
• X1 and X2 together are the second bond of a double bond between the carbon atoms to which they are bound;
• X3 and X4 together are the second bond of a double bond between the carbon atoms to which they are bound;
• one of the combinations of the radicals X5 and X7, X6 and X7 or X7 and X8 together is the second bond of a double bond between the carbon atoms to which they are bound and the remaining radicals X5, X6, X7 and X8 are each hydrogen;
• and isomers and mixtures thereof;
• b) the reaction mixture obtained in step a) is optionally subjected to a decarboxylation to give a compound of the formula (I-b),
• where
• R2 is C1-C4-alkyl;
• one of the combinations of the radicals X5 and X7, X6 and X7 or X7 and X8 together is the second bond of a double bond between the carbon atoms to which they are bound and the remaining radicals X5, X6, X7 and X8 are each hydrogen;
• and isomers and mixtures thereof;
• c) the reaction mixture obtained in step b) is optionally subjected to a hydrogenation to give a compound of the formula (I-c)
• where
• R2 is C1-C4-alkyl.