Closed Atom Economy Chemistry: Principles, Frameworks, and Theoretical Horizons

Modern chemical synthesis frequently generates substantial environmental burdens through the production of waste liquids, waste salts, and chemical by-products, even within the frameworks of conventional atom economy. This paper introduces Closed Atom Economy Chemistry (CAEC), a transformative paradigm that redefines chemical synthesis by enforcing a strict zero-waste boundary condition where all reactant atoms must 100 percent enter the target product. We present the fundamental theoretical foundations, a rigorous mathematical framework modeling multi-step closed reaction networks, and stoichiometric strategies focused on molecular topology and skeletal editing. Furthermore, we explore advanced catalytic systems—including transition metal catalysis, organocatalysis, and electrocatalysis—that facilitate zero-waste pathways without relying on consumable activating reagents. Finally, we analyze the thermodynamic and kinetic constraints governing zero-waste systems and highlight how renewable energy inputs, such as light and electricity, can overcome uphill free energy landscapes. CAEC establishes a comprehensive roadmap for achieving absolute material closure and long-term sustainability in chemical manufacturing.