The chemical which is not required for the preparation of soap in the laboratory is

In the preparation of soap fatty organic acid (vegetable oil), common salt and strong bases like NaOH (for laundry soap) KOH (for toilet soap) required but ${\text{NaHCO}}_3$ is a mild non-corrosive base which is not suitable for preparation of soap.  To get soap from soap solution, addition of  NaCl necessary.