Green Chemistry Unit 3 Quiz

UNIT 3: GREEN CHEMISTRY

• Green chemistry is the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture, and applications of chemical products.
• Green chemistry aims to minimize environmental pollution.
• Green chemistry was developed by Paul Anastas and John Warner in 1998.
• Green chemistry principles provide a framework for creating greener chemical products, processes, and products.

CONTENTS

• Introduction to Green Chemistry
• Principles of Green Chemistry
• Emphasis on principles 1, 2, 5, 6, and 9
• Real-world cases: Surfactants for CO2
• Real-world cases: Designing for environmentally safe marine antifoulants
• Real-world cases: Biodegradable plastics
• Biodiesel synthesis and use

CONTENT 1: INTRODUCTION TO GREEN CHEMISTRY

• Green chemistry is the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture, and applications of chemical products.
• Green chemistry is environmentally friendly synthesis.
• Environmental pollution is minimized to ensure environmentally responsible chemical processes.
• Developed in 1998 by Paul Anastas and John Warner.

IMPORTANCE OF GREEN CHEMISTRY IN DAILY LIFE

• Green dry cleaning of clothes
  • A green commercial approach uses CO2 along with surfactants.
  • The previous solvent Perchloroethylene (PERC) is a groundwater contaminant and suspected carcinogen.
• Biodegradable Plastics
  • PLA (polylactic acid) can be a substitute for petrochemical plastics.
  • Eco Flex is a biodegradable polyester film with high resistivity.

INTRODUCTION (CONTINUED)

• Medicine: Green chemistry plays a crucial role in pharmaceuticals.
  • It aims to develop medicines with high efficiency and reduced side effects. Efficient synthesis involving fewer steps, with high efficiency of the synthesis. Example: Ibuprofen can be synthesized through 3 steps instead of 6.
• Greener way to putting out fires:
  • Existing firefighting foams have detrimental environmental impacts. PYROCOOL FEF is designed as a greener fire-fighting foam.
• Eco-friendly paints:
  • Oil-based paints have volatile organic compounds (VOCs) and heavy metals such as As, Pb, and Cr. They negatively affect human organs. Nerolac is presented as an eco-friendly, non-toxic, paint.
• Getting clear water from turbid water:
  • Alum is used in water treatment for coagulation/ clarification. However, Alum increases toxins in treated water and can lead to Alzheimer's.
  • Natural coagulants, such as Tamarind seed kernel powder, are a biodegradable and environmentally friendly alternative.

PRINCIPLE 1: PREVENTION OF WASTE

• It's more advantageous to prevent waste than to treat it later.
• Waste (by-products or unreacted starting material) discharged into the atmosphere, sea, or land causes environmental pollution, harms human health, and increases manufacturing costs.
• Minimizing waste generation in chemical synthesis is crucial for the environment and human health.
• E-factor (environmental factor): Measures the amount of waste created in a process. A higher E-factor indicates more waste. Ideally, the E-factor should be close to zero.

PRINCIPLE 2: ATOM ECONOMY

• Atom economy quantifies the efficiency of the process by incorporating the starting materials and reagents into the final product. A higher atom economy implies a more efficient process, generating less waste.
• Calculating Atom economy:
  • Write a balanced chemical equation.
  • Calculate the molecular weights of all reactants and desired product.
  • Apply the formula.

PRINCIPLE 3: LESS HAZARDOUS CHEMICAL SYNTHESIS

• Chemical reactions should avoid generating harmful products or by-products and optimize processes while minimizing toxic substances. (Using cleaner, or less toxic, materials is preferred).
• Example: Replacing phosgene with CO2 in polyurethane synthesis.

PRINCIPLE 4: DESIGNING SAFER CHEMICALS

• Chemical products should be designed to maintain their function while minimizing toxicity.
• Safer chemicals cause minimal negative impact on human health and the environment.
• Example: Replacing harmful solvents like thalidomide.

PRINCIPLE 5: SAFER SOLVENTS AND AUXILIARIES

• Use of auxiliary substances (e.g., solvents) should be minimized or eliminated wherever practical.
• The use of harmless or non-toxic solvents is preferred.
• Typical problems with solvents: Expense, Depletion of Fossil Fuels, Toxicity, Flammability, Carcinogenic potential, and Ozone Depletion.
• The preferred solvents are readily available, cheap, easily separable, reusable, non-toxic, inert and do not pollute the environment or cause health hazards.

PRINCIPLE 6: DESIGN FOR ENERGY EFFICIENCY

• Minimize energy consumption and use environmentally friendly energy sources (e.g., photochemical, microwave, ultrasound).
• Conduct chemical reactions at ambient temperature and pressure.
• Use catalysts to lower energy requirements.
• Fewer steps mean less energy is required for the reaction, which also lowers waste.

PRINCIPLE 7: USE OF RENEWABLE FEEDSTOCKS

• Prefer raw materials from renewable sources over non-renewable ones, minimizing environmental impact.
• Use bio-based starting materials (e.g., Corn starch).
• Example: Utilizing renewable feedstocks like corn starch as a source of adipic acid for making a biodegradable plastic.

PRINCIPLE 8: REDUCE DERIVATIVES

• Minimize the use of blocking groups, protection/deprotection, or temporary modification of chemical processes, as these steps consume reagents and generate waste.
• Protective groups are used to protect specific functional groups during a reaction sequence but need to be subsequently removed which requires more steps in the process, more reagents and more waste..

PRINCIPLE 9: CATALYSIS

• Catalytic reagents are superior to stoichiometric ones.
• Catalysts increase reaction rates and yield.
• Catalysts create more selectivity, and reduce the amount of waste products.
• Stoichiometric syntheses can be slow, and generate significant waste..

PRINCIPLE 10: DESIGN FOR DEGRADATION

• Chemical products should break down quickly and efficiently after they've completed their function.
• The degradation products must be environmentally harmless.
• Chemical products should be synthesized with environmentally benign degradation products.
• Example: Insecticides, Organophosphates, carbamates, and organochlorides.

PRINCIPLE 11: REAL-TIME ANALYSIS FOR POLLUTION PREVENTION

• Real-time analysis helps monitor processes and prevent the formation of hazardous substances during chemical reactions.
• In-process, real-time analysis can prevent accidents and stop reactions.
• Real-time analysis techniques can be used to manage processes and improve efficiency.

PRINCIPLE 12: INHERENTLY SAFER CHEMISTRY FOR ACCIDENT PREVENTION

• Design chemical processes to minimize the potential for accidents (e.g., releases, explosions, fires).
• Prioritize using safer substances and minimizing dangerous process conditions.
• Minimize the potential for dangerous releases, explosions, or fires. Example: Bhopal gas tragedy, Flixborough accident.