Design of chemical products and processes that reduce or eliminate hazardous substances and waste. Anastas & Warner's twelve principles; quantitative metrics (atom economy, E-factor, PMI) for assessing process sustainability.
green-chemistry
Atom economy
Fraction of the total mass of all reactants that ends up in the desired product: AE = (M_product / Σ M_reactants) × 100%. Unlike yield, it…
E-factor
E = (total mass of waste) / (mass of product), where 'waste' includes everything except the desired product (solvents, by-products, spent…
Twelve principles of green chemistry
Anastas & Warner (1998) framework: (1) prevent waste, (2) atom economy, (3) less hazardous synthesis, (4) safer chemicals, (5) safer…
Process mass intensity (PMI)
PMI = (total mass of materials used) / (mass of product), where 'materials' includes reagents, solvents, process aids, and water. Strictly…
Renewable feedstock
Biomass-derived starting material (cellulose, lignin, vegetable oils, sugars, chitin) used as an alternative to petroleum-derived inputs. …
Life-cycle assessment (LCA)
Cradle-to-grave quantification of environmental impact across raw-material extraction, production, use, end-of-life. ISO 14040/44…
Supercritical CO₂ as solvent
sc-CO₂ (Tc=31°C, Pc=74 bar) is nontoxic, tunable, recyclable solvent. Applications: decaffeination, dry-cleaning, polymerization,…
Ionic liquids
Room-temperature molten salts (e.g., [BMIM][BF4]) with negligible vapor pressure. Tunable polarity + solubility; used in cellulose…
Click chemistry (CuAAC)
Cu(I)-catalyzed azide-alkyne cycloaddition → 1,4-disubstituted triazole. Quantitative, bioorthogonal. Sharpless/Meldal/Bertozzi Nobel 2022.…
Industrial biocatalysis
Engineered enzymes (directed evolution) for manufacturing. Codexis transaminases for sitagliptin; lipases for chiral resolution;…
E-factor (Sheldon)
kg waste / kg product; pharma ~25-100; fine chem 5-50; bulk <5; oil refining <0.1; benchmarks industrial sustainability.
Solvent-free reactions & mechanochemistry
Ball milling neat reactions; circumvents solvent waste; MOFs, pharma cocrystals; IUPAC 'top 10 emerging' 2019.
Biocatalysis & directed evolution
Enzymes in non-natural reactions; Arnold directed evolution (2018 Nobel); sitagliptin, HIV drug processes.
Deep eutectic solvents & bio-based solvents
ChCl + urea etc., lowered mp; biodegradable; replace volatile organics; lignocellulosic biomass processing.
Continuous flow chemistry
Microreactors with short residence times; improved heat/mass transfer; access hazardous intermediates safely.
Circular carbon economy
CO₂ as feedstock via electrocatalysis, thermocatalysis; methanol, ethylene, fuels; hydrogen from renewables.