Using the acetoacetic ester synthesis , prepare 3,4-dimethyl-2-pentanone

To prepare 3,4-dimethyl-2-pentanone using the acetoacetic ester synthesis, we will start with two molecules: ethyl acetoacetate and 1,3-dimethyl-2-butene. Here's a step-by-step explanation of the synthesis:

1. Start by converting ethyl acetoacetate to its enolate form. To do this, mix ethyl acetoacetate with a strong base, such as sodium ethoxide (NaOEt) or sodium hydroxide (NaOH). The base will deprotonate the alpha-carbon adjacent to the ester group, forming the enolate.

2. Next, add 1,3-dimethyl-2-butene to the reaction mixture. The enolate will react with the 1,3-dimethyl-2-butene through a nucleophilic addition reaction. The carbon-carbon double bond in 1,3-dimethyl-2-butene will act as the electrophile, while the enolate will act as the nucleophile.

3. After the addition reaction, the resulting product will contain the desired 3,4-dimethyl-2-pentanone moiety. However, it will also have an additional ethyl group attached to the ketone. To remove this ethyl group, we need to perform a hydrolysis reaction.

4. To hydrolyze the ethyl group, add aqueous acid (such as hydrochloric acid, HCl) to the reaction mixture. The acid will protonate the ester group, causing it to break apart and form a carboxylic acid.

5. Finally, heat the reaction mixture to drive off the excess water and isolate the 3,4-dimethyl-2-pentanone product.

It's important to note that the acetoacetic ester synthesis is a multi-step reaction that involves several chemical transformations. It requires an understanding of organic chemistry principles and the proper handling of reagents. Therefore, it is essential to have a background in chemistry or consult a qualified chemist for practical execution.