How to Prepare Meldrum's acid?

The preparation steps of Meldrum's acid are as follows:

(a) mixing acetone, malonic acid, and an acid catalyst in molar ratios from 1.0:1.0:0.005 to 2.3:1.0:0.12, respectively, to form a mixture of - a solution phase of the acetone, acid catalyst, and from 5 to 25 mole percent of the malonic acid; and a solid phase of from 75 to 95 mole percent of the malonic acid; and

(b) adding acetic anhydride to the mixture obtained from step (a), the total amount of acetic anhydride which is added is from 0 percent molar excess to 150 percent molar excess relative to the total malonic acid molar concentration, said addition of acetic anhydride occurring at a rate such that at any given time during the addition of acetic anhydride the concentration of unreacted acetic anhydride in the mixture does not exceed 14 mole percent relative to the malonic acid molar concentration concurrently present in the solution phase.

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