Aryl thiols are important building blocks in the synthesis of sulfur-containing natural products and pharmaceutically important compounds. We are interested in 3-aryl(thio)-propanoic acids because they are key intermediates for S-heterocycles. This research is focused on the synthesis of 3-aryl(thio)-propanoic acids from aryl thiols via SN2 reactions. The hypothesis is that the electronic withdrawing and donating group on the aromatic ring will affect the reactivity of aryl thiols in SN2 reaction and thus the chemical yields. The scope of aryl thiols will be explored. The results on various electron-donating and electron-withdrawing groups will be presented.