The synthesis of diethyl malonate

diethyl malonate from diethyl malonate is an important position in the field of organic synthesis. Its synthesis method has unique and subtle aspects.

In the past, the common method for preparing diethyl malonate was chloroacetic acid as the starting material. First, chloroacetic acid reacts with sodium carbonate to form sodium chloroacetate. This step of the reaction, such as the slow pouring of chloroacetic acid into a vessel containing a sodium carbonate solution, the two blend, just like dancers dancing together on the stage, and a metathesis reaction occurs. The hydrogen of chloroacetic acid combines with the carbonate to form carbon dioxide, which escapes, and the chloroacetic acid and sodium ions join hands to form sodium chloroacetate.

Then, sodium chloroacetate reacts with sodium cyanide, which is a key turning point. Cyanide ions are like warriors, resolutely replacing chlorine atoms to form sodium cyanoacetate. This process requires strict control of the reaction conditions. Temperature and the proportion of reactants are the keys to success or failure. Just like craftsmen carve beautiful jade, the slightest difference is lost.

After hydrolysis, the cyanyl group is hydrolyzed under suitable acid and alkali conditions. In case of dead wood in spring rain, it is turned into carboxyl group to obtain malonic acid. However, the malonic acid needs to be esterified with ethanol to obtain diethyl malonate. Put malonic acid and ethanol in a reactor, add an appropriate amount of concentrated sulfuric acid as a catalyst, and heat it up. At this time, the concentrated sulfuric acid is like a magical conductor, leading the interaction between the two molecules. The hydroxyl group and the carboxyl group remove a molecule of water, and the chemical bonds are rearranged and combined to form diethyl malonate.

There is also another way, using ethyl acetate as the starting material. Two molecules of ethyl acetate under the catalysis of strong bases undergo a Claisen condensation reaction. The power of strong bases breaks the original molecular tranquility of ethyl acetate, causing its molecules to lose alpha-hydrogen and form carbon negative ions. This carbon negative ion is like an active hunter, quickly attacking the carbonyl carbon of another molecule of ethyl acetate, forming a new carbon-carbon bond, which is then acidified and cleverly converted into diethyl malonate. Although the steps of this approach are different, they all achieve the purpose of synthesis and add bright pearls to the treasure house of organic synthetic chemistry.