Green chemistry is an approach to chemistry that aims to prevent pollution and reduce resource use by redesigning substances, processes and products from the outset. It is guided by principles such as preventing waste, using safer solvents and reagents, designing for energy efficiency and choosing renewable feedstocks when possible.

A core objective is to avoid hazardous substances rather than manage them after they are created. This includes replacing toxic reagents and solvents with safer alternatives, minimizing volatility and bioaccumulation, and designing molecules that break down into harmless products at the end of their life. Metrics such as atom economy and E factor quantify how efficiently raw materials become product versus waste.

Catalysis plays a central role. Catalytic processes often operate under milder conditions, with higher selectivity and lower energy demand. Biocatalysts such as enzymes enable reactions in water at ambient temperature and pressure. Other research targets safer reaction media, including water, supercritical carbon dioxide, ionic liquids and deep eutectic solvents, aiming to balance performance with toxicity and environmental impact.

Energy efficiency is another key theme, encouraging low temperature and low pressure processes and the integration of renewable energy. In materials and product design, chemists work to avoid persistent pollutants and design polymers and chemicals that maintain performance while being recyclable or biodegradable.

Overall, green chemistry shifts focus from treating pollution to preventing it through intelligent molecular and process design. It aligns economic and environmental benefits by reducing waste, energy use and regulatory burden while often improving yields and process robustness.