To design a retrosynthesis for the synthesis of 2-phenylpropionic acid from benzene, ethylene, and CO, we will break down the target molecule into simpler precursors and identify the reactions needed to form the desired product. Here's a possible retrosynthetic pathway:Target molecule: 2-phenylpropionic acid CHCHCHCOOH 1. Break the C-C bond between the phenyl group and the propionic acid moiety. Precursors: Benzene CH and Propionic acid CHCHCOOH 2. To synthesize propionic acid from ethylene and CO, we can use the hydrocarboxylation reaction also known as the Kolbe-Schmitt reaction . Precursors: Ethylene CH and CORetrosynthetic pathway:Step 1: Benzene + Propionic acid 2-phenylpropionic acidStep 2: Ethylene + CO Propionic acidForward synthesis:Step 1: Hydrocarboxylation of ethyleneCH + CO CHCHCOOH Propionic acid Step 2: Friedel-Crafts alkylation of benzeneCH + CHCHCOOH CHCHCHCOOH 2-phenylpropionic acid In this forward synthesis, we first perform the hydrocarboxylation of ethylene to form propionic acid. Then, we carry out a Friedel-Crafts alkylation reaction between benzene and propionic acid to form the desired product, 2-phenylpropionic acid.