Preparation of beta-dione

The present invention relates to a preparation method of beta-diketone; Claisen condensation reaction is adopted; the chemical general expression of the beta-diketone is R1COCH2COR2, wherein, R1 is C6-C12 alkyl, and R2 is phenyl or alkylphenyl; the method comprises the following steps: ester, phenyl ketone and partial solvent are pre-mixed for spare; a condensating agent and remaining solvent are added in a reactor, and the temperature is raised under nitrogen atmosphere; during the period when the temperature of the reactor is raised to the needed temperature of the condensation reaction, the pre-mixed material is dropwise added in the reactor for carrying out the condensation reaction with a system which is composed of the condensating agent and the remaining solvent under an infinite reflux condition; after the pre-mixed material is dropwise added, heat-preserving condensation reaction is carried out continuously under the infinite reflux condition. The ester and the condensating agent in the raw material are contacted when the reacting condition is achieved, and acylation reaction is slow reaction, relative to the Claisen condensation reaction, thus being capable of better solving the acidylation problem of the ester, and reducing the effect of the acylation reaction to the minimum; the yield of the beta-diketone is more than or equal to 90 percent.