Green Chemistry — Chapter 1 Study Materials Flashcards

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Green Chemistry

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Design of chemical products and processes that reduce or eliminate hazardous substances. It emphasizes pollution prevention, resource efficiency, and safer alternatives.

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Atom Economy

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A theoretical metric measuring the proportion of reactant atoms incorporated into the desired product. High atom economy indicates fewer atoms wasted as by-products.

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E-factor

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A process-based metric defined as mass of waste produced per mass of product. Lower E-factor values indicate greener, less wasteful processes.

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Life Cycle Assessment

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An analysis of environmental impacts over a product's entire life cycle from cradle to grave (or cradle to cradle). It identifies hotspots and compares alternatives across stages.

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LD50

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Lethal Dose 50%: the dose of a substance that kills 50% of test animals, usually expressed in mg/kg. Lower LD50 values indicate higher acute toxicity.

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LC50

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Lethal Concentration 50%: concentration in air or water that kills 50% of test animals, expressed in ppm or mg/m³. Used for inhalation or aquatic toxicity assessment.

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Ames Test

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A bacterial assay that screens chemicals for mutagenicity using Salmonella strains and metabolic activation. A positive result flags potential carcinogens that may need further study.

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Three Pillars

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The Environmental, Social, and Economic dimensions of sustainable development. Sustainability requires balancing all three for long-term viability.

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Circular Economy

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An economic model that keeps resources in use through reuse, remanufacture, and recycling, minimizing waste and resource depletion. It complements green chemistry by designing materials for circularity.

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Four Conditions

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The Natural Step's system conditions: avoid build-up of earth-crust materials and persistent man-made substances, not damage natural cycles, and use resources efficiently and fairly. They guide high-level sustainability choices.

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Rearrangement Reaction

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A reaction where atoms or groups shift within a molecule, often with high atom economy because no atoms are lost. Examples include Claisen and Pinacol rearrangements.

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Addition Reaction

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A reaction that adds reagents across unsaturated bonds and is typically atom-efficient because most atoms end up in the product. Diels–Alder and Michael additions are common examples.

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Substitution Reaction

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A reaction that replaces one group with another and usually generates a by-product, lowering atom economy. Many common syntheses use substitution steps.

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Elimination Reaction

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A reaction that removes atoms or groups from adjacent atoms to form unsaturation, often producing small molecule by-products and reducing atom economy.

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Wittig Reaction

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A method to form alkenes that generates triphenylphosphine oxide ($Ph_3P=O$) as stoichiometric waste. This reduces atom economy and complicates industrial use.

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Diels–Alder

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A cycloaddition forming two C–C bonds in one step; highly atom-efficient with few by-products. It is widely used for building ring systems in a single operation.

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Beckmann Rearrangement

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A transformation converting oximes to amides, historically using strong acids and producing acidic waste. Greener alternatives use zeolite catalysts to reduce waste and improve reusability.

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Hazard vs Risk

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Hazard is the intrinsic potential of a substance to cause harm; risk is the likelihood that harm will occur and depends on exposure. Green chemistry aims to reduce hazard, not only exposure.

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Sheldon E-Factor

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Roger Sheldon's E-factor concept quantifies how much waste industry sectors produce per product unit. It highlighted large differences between sectors and drove interest in greener processes.

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Pinacol Rearrangement

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A conversion of vicinal diols to carbonyl-containing compounds under acid catalysis. Greener catalysts (e.g., supported acids) can improve yields and reduce hazardous acid waste.