Environmental Chemistry - Green Chemistry

Green Chemistry is defined as the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. It is also known as 'Sustainable Chemistry'.

The 12 Principles of Green Chemistry, formulated by Paul Anastas and John Warner, serve as a guide for sustainable practices. These include waste prevention, atom economy, and the use of renewable feedstocks.

Atom Economy: This concept evaluates the efficiency of a chemical reaction by calculating the proportion of starting materials that end up in the final desired product. A process with $100\%$ atom economy incorporates all reactant atoms into the product.

Green Solvents: Traditional volatile organic solvents (VOCs) are often toxic. Green chemistry promotes the use of safer alternatives like water ($H_2O$), supercritical carbon dioxide ($scCO_2$), or ionic liquids.

Use of Catalysts: Catalytic reagents are superior to stoichiometric reagents because they are effective in small amounts, can be reused, and lower the activation energy ($ΔG^\ddagger$) of the reaction.

Green Synthesis in Daily Life: Examples include using $H_2O_2$ (hydrogen peroxide) instead of $Cl_2$ for bleaching paper and using liquid $CO_2$ instead of tetrachloroethene ($Cl_2C=CCl_2$) for dry cleaning clothes.

Energy Efficiency: Chemical syntheses should be designed to occur at ambient temperature and pressure to minimize energy consumption.