Three kinds of 1,3-dioxane-4,6-dione were synthesized from malonic acid and ketone using La(OTf)₃ as catalyst and acetic anhydride as condensing regent. The effects of the molar ratio of malonic acid and ketone, reaction temperature, reaction time, catalyst dosage and its stability on the yield were investigated. The optimum conditions were as follows: 0.1 mol malonic acid, n(malonic acid)∶n(ketone)＝1.0∶1.1, the amount of catalyst 0.3 mol%, reaction temperature 30 ℃, reaction time 3.0 h. Under above reaction conditions, the product yields achieved up to 62.3%～77.5%.

Key words: 1,3-dioxane-4,6-dion, La(OTf)₃, malonic acid, ketone