– 4-Chlorophenoxyacetic acid (sodium) (4-CPA (sodium); p-Chlorophenoxyacetic acid (sodium)) is a chlorinated phenolic compound that functions as both a plant growth regulator and herbicide. At low concentrations, it promotes plant growth, while at high concentrations, it inhibits growth, particularly in dicotyledonous plants. This compound can serve as a biochemical material or organic compound in life sciences research.