The malonic ester synthesis is a carbonyl alkylation reaction. It is used to prepare carboxylic acids from primary alkyl halides, lengthening the carbon chain by two atoms. Thus, the product can be visualized as being a "substituted acetic acid." The reaction consists of three steps: generation of the enolate anion followed by SN2 reaction with a primary alkyl halide, ester hydrolysis under acid conditions, and decarboxylation. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions