Green Chemistry
Green chemistry is a way of thinking, a philosophy rather than a set of regulations or guidelines. It is an intentional and deliberate design of chemical products and processes which are environmental friendly and which severely restrict or entirely avoid usage and generation of hazardous substances. Waste not, want not!
Guiding principles of Green Chemistry
Understanding Cholesterol Synthesis is always challenging for me but thanks to all math help websites to help me out.
Practical Green Chemistry
An ideal green process development should de aimed for 100% yield and 0% effluent. In practice a minimum of 65-75% of atom economy. Here zero percent effluent means 100% Atom economy.
Instead of measuring, monitoring, controlling toxicity, design molecules that are inherently non-toxic in the first place.
Remember PASE: Pot, Atom, Step Economy.
Safe, Simple, Minimum number of steps, 100 % yield, readily available materials
No waste reagents generation, environmentally acceptable processes
Benign enviro-friendly disposal, recycle and reuse, reduce use of chemicals,
Energy usage, time cycle management
Replace hazardous materials and hazardous and inefficient processes
Further tips for Green Chemistry
Essence of green chemistry:
Right route selection, Right conditions, Right reagent Best case scenario
Wrong route selection, Wrong conditions, No reaction
Wrong reaction Worst case scenario
Dos of Green Chemistry:
Perspectives in Green Chemistry
Three key developments in green chemistry set out by Ryoji Noyori (Nobel laureate, 2001) are:
Supercritical CO2 - green solvent
Aqueous H2O2 - for clean oxidations
H2 - Asymmetric synthesis.
Examples of applied green chemistry are:
Supercritical water oxidation: Use of supercritical water to clean up pollutants like PCBs by oxidation
On water reactions: reaction as emulsion in water, avoiding the use of solvents
Dry media reactions: Also known as “solventless reaction” or “solid state reaction”. Examples are: 1.liquid reactant is used without solvent. 2. Converge reaction without solvent in microwave oven
Guiding principles of Green Chemistry
- Prevention: don’t create waste in the first place. better than clean up afterwards
- Atom Economy: See that most of atoms in the starting materials end up in the product. avoid unreached materials as well as hazardous side products
- Less Hazardous Chemical Synthesis: products should be nontoxic to begin with
- Design Safer processes: products should be highly efficacious and least toxic.
- Safety Solvents & Auxiliaries: avoid unnecessary use of solvents and other substances like separation agents. If not possible to entirely eliminate, use innocuous substances in minimal quantities
- Design for Energy Efficiency: use ambient temperature and pressure as much as possible.
- Use Renewable Feed stocks: avoid dependable raw material or feedstock
- Reduce Derivatives: avoid, blocking group, protection/deprecation, temporary modifications
- Catalysis: selective catalysts rather than chronometric reagents
- Design for Degradation: design degradation of products after their intended use
- Real-Time Analysis for Pollution Prevention: Develop analytical methods so that in-process real time monitoring avoids production of hazardous substances
- Inherently Safer Chemistry for Accident Prevention: minimize potential for chemical accidents including unintended release into atmosphere, explosions, an fires
Understanding Cholesterol Synthesis is always challenging for me but thanks to all math help websites to help me out.
Practical Green Chemistry
An ideal green process development should de aimed for 100% yield and 0% effluent. In practice a minimum of 65-75% of atom economy. Here zero percent effluent means 100% Atom economy.
Instead of measuring, monitoring, controlling toxicity, design molecules that are inherently non-toxic in the first place.
Remember PASE: Pot, Atom, Step Economy.
Safe, Simple, Minimum number of steps, 100 % yield, readily available materials
No waste reagents generation, environmentally acceptable processes
Benign enviro-friendly disposal, recycle and reuse, reduce use of chemicals,
Energy usage, time cycle management
Replace hazardous materials and hazardous and inefficient processes
Further tips for Green Chemistry
Essence of green chemistry:
Right route selection, Right conditions, Right reagent Best case scenario
Wrong route selection, Wrong conditions, No reaction
Wrong reaction Worst case scenario
Dos of Green Chemistry:
- Run larger batches which can reduce labor and overhead charges.
- The cost is directly proportional to overall yield.
- The yield is inversely proportional to the number of synthetic steps.
- The important and significant strategy should be to considered for Convergent synthesis rather than linear synthesis to improve the overall yield
- Reduce the by products
Perspectives in Green Chemistry
Three key developments in green chemistry set out by Ryoji Noyori (Nobel laureate, 2001) are:
Supercritical CO2 - green solvent
Aqueous H2O2 - for clean oxidations
H2 - Asymmetric synthesis.
Examples of applied green chemistry are:
Supercritical water oxidation: Use of supercritical water to clean up pollutants like PCBs by oxidation
On water reactions: reaction as emulsion in water, avoiding the use of solvents
Dry media reactions: Also known as “solventless reaction” or “solid state reaction”. Examples are: 1.liquid reactant is used without solvent. 2. Converge reaction without solvent in microwave oven