Micro‐Scale Synthesis of Chemical Weapons Convention Related Dialkyl Alkylphosphonates by Using Cesium Carbonate

ABSTRACT Organophosphorus compounds, particularly phosphonates, represent an important class of P─C bonded molecules with widespread applications in pharmaceutical, agrochemical, and materials chemistry as flame retardants, plasticizers, and so on. Their structural diversity and tunable reactivity make them valuable synthetic intermediates. Among these, dialkyl alkylphosphonates are listed under Schedule 2.B.04 of the Chemical Weapons Convention (CWC) due to their relevance as precursors, by‐products, and degradation products of nerve agents, thereby necessitating reliable and safe synthetic access for analytical and off‐site verification purposes. Herein, we report a safe and efficient micro‐synthesis method for CWC‐related dialkyl alkylphosphonates using the Michaelis–Becker reaction under optimized conditions. The reaction employs cesium carbonate (Cs 2 CO 3 ) as a mild inorganic base and dimethylformamide (DMF) as the solvent. The optimized protocol offers several advantages over the previous methods, avoiding the hazards associated with reactive alkali metal bases, comparable improved reaction time, and provides high yields (88%–98%). The developed methodology provides a practical and safer alternative for the preparation of reference standards and strengthens the synthetic and analytical capabilities of laboratories involved in CWC‐related chemical verification.