Introduction to Green Chemistry
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Questions and Answers

What is the role of ethylaluminum dichloride in the polymerization of isobutyl vinyl ether (IBVE)?

  • It acts as a catalyst for the reaction.
  • It serves as a Lewis acid. (correct)
  • It functions as a Lewis base deactivator.
  • It is the initiator for the polymerization.

At what temperature and pressure was the polymerization of IBVE conducted in scCO2?

  • 50 °C and 350 bar
  • 40 °C and 345 bar (correct)
  • 20 °C and 300 bar
  • 35 °C and 400 bar

What was the yield of poly(IBVE) in the polymerization described?

  • 85%
  • 78%
  • 91% (correct)
  • 75%

What type of polymerization process was used to form poly(IBVE) in scCO2?

<p>Heterogeneous precipitation (D)</p> Signup and view all the answers

Which reaction was first reported in scCO2 in 1987?

<p>Stoichiometric Diels–Alder reaction (D)</p> Signup and view all the answers

What is the primary goal of the most important principle of green chemistry?

<p>To eliminate or decrease the formation of hazardous products (B)</p> Signup and view all the answers

In the preparation of an amide shown in Scheme 2.3, what percentage of atom economy was achieved?

<p>65.4% (A)</p> Signup and view all the answers

Which method is suggested to minimize toxicity in chemical syntheses?

<p>Designing methods to generate non-toxic substances (C)</p> Signup and view all the answers

What major side effect was associated with thalidomide when prescribed to pregnant women?

<p>Abnormally short limbs and other malformations (C)</p> Signup and view all the answers

What is the primary substance used in the oxidation of cyclohexene to adipic acid as per Scheme 2.4?

<p>30% hydrogen peroxide (B)</p> Signup and view all the answers

What was the primary use of thalidomide when it was first introduced?

<p>As an antiemetic for pregnant women (A)</p> Signup and view all the answers

Why is controlling the formation of hazardous products important in chemical synthesis?

<p>It reduces environmental and health risks (C)</p> Signup and view all the answers

What does the concept of atom economy refer to in green chemistry?

<p>The percentage of atoms from reactants that become part of the final product (A)</p> Signup and view all the answers

What is one advantage of using ionic liquids in chemical processes?

<p>They reduce the volatility of solvents. (C)</p> Signup and view all the answers

What is a primary goal of green chemistry concerning energy use?

<p>To decrease energy requirements whenever possible. (C)</p> Signup and view all the answers

What is a key disadvantage of fluorous solvents mentioned in the content?

<p>They are expensive and toxic gases are required for their production. (D)</p> Signup and view all the answers

In what type of reaction system does the Sonogashira coupling occur as described?

<p>Liquid/liquid fluorous biphasic system (D)</p> Signup and view all the answers

Which method is NOT mentioned as a green energy source for chemical reactions?

<p>Fossil fuel combustion (B)</p> Signup and view all the answers

What is a benefit of using microwave conditions in the reaction of azaheterocycles with alkyl halides?

<p>They lead to higher purity and faster reaction times. (B)</p> Signup and view all the answers

What defines a supercritical liquid (SCL)?

<p>It is above its critical temperature and critical pressure. (A)</p> Signup and view all the answers

What was the role of silica in the ultrasound-assisted reaction outlined in the content?

<p>It acted as a promoter for the reaction. (C)</p> Signup and view all the answers

Which substance is the most widely used supercritical liquid?

<p>Carbon dioxide (C)</p> Signup and view all the answers

What reaction takes place in the Sonogashira coupling example provided?

<p>Synthesis of 1-(4-nitrophenyl)-2-phenylacetylene (B)</p> Signup and view all the answers

In the context provided, which statement about N-alkylation of azaheterocycles under microwave conditions is correct?

<p>The reaction exclusively produces N-alkyl derivatives. (D)</p> Signup and view all the answers

Which solvent mixture is mentioned in the Sonogashira coupling process?

<p>FC-72, a mixture perfluorohexane (B)</p> Signup and view all the answers

Which of the following is a characteristic of using green energy sources in chemical reactions?

<p>They often lead to a decrease in reaction time. (D)</p> Signup and view all the answers

What effect does varying temperature and pressure have on supercritical liquids?

<p>It changes their specific properties. (D)</p> Signup and view all the answers

What is a common reaction performed using alkyl halides and azaheterocycles under microwave conditions?

<p>N-alkylation to produce N-alkyl derivatives. (A)</p> Signup and view all the answers

What temperature condition is specified for the Sonogashira coupling reaction?

<p>55 °C (C)</p> Signup and view all the answers

What is the primary benefit of microfabricated microfluidic analytical devices?

<p>They integrate multiple sample-handling processes on a microchip. (A)</p> Signup and view all the answers

Which of the following is a characteristic of green analytical chemistry?

<p>It aims for faster and simpler onsite monitoring of pollutants. (C)</p> Signup and view all the answers

What type of technologies has driven the interest in biosensor technology?

<p>Faster, simpler, cheaper, and better monitoring tools. (A)</p> Signup and view all the answers

Why is the urea/hydrogen peroxide complex considered safer than liquid hydrogen peroxide?

<p>It is cheap, stable, and green. (A)</p> Signup and view all the answers

What type of applications have been developed using capillary electrophoresis/electrochemistry microchips?

<p>Rapid separation and detection of pollutants. (A)</p> Signup and view all the answers

What is a key step in the complete assay process using lab-on-a-chip devices?

<p>Integration of electrophoretic separations. (C)</p> Signup and view all the answers

What major factor should be considered to prevent accidents in chemical processes?

<p>The selection of safer reagents. (B)</p> Signup and view all the answers

Which is NOT a recommended benefit of using lab-on-a-chip technology?

<p>Increased lab equipment costs. (C)</p> Signup and view all the answers

What is a primary advantage of using ionic liquids in catalysis?

<p>They can be used in biphasic catalysis due to phase separation. (A)</p> Signup and view all the answers

Which property of ionic liquids contributes to increased catalyst lifetime?

<p>They are non-nucleophilic and provide an inert environment. (A)</p> Signup and view all the answers

Which of the following is a key characteristic of poly(ethylene glycol) (PEG)?

<p>PEG is a linear polymer made from ethylene oxide. (D)</p> Signup and view all the answers

What makes PEG a better alternative compared to volatile organic solvents?

<p>PEG can be easily separated from the reaction medium by simple procedures. (D)</p> Signup and view all the answers

What is a disadvantage common to both PEGs and ionic liquids?

<p>They require organic solvents for the extraction of reaction products. (A)</p> Signup and view all the answers

Why are low molecular weight PEG derivatives preferred in reactions?

<p>They are typically liquids at room temperature and have low melting points. (A)</p> Signup and view all the answers

Which is true about the diffusion rate of gases in ionic liquids?

<p>The diffusion rate of gases is higher, increasing reaction rates. (C)</p> Signup and view all the answers

What is a common characteristic of ionic liquids containing BF41 or PF61 anions?

<p>They are widely used in biphasic catalysis. (D)</p> Signup and view all the answers

Flashcards

Immobilized solvents

Solvents that are fixed in place, often used to improve chemical processes.

Low-volatility solvents

Solvents that do not easily evaporate, reducing losses and improving efficiency.

Ionic liquids

Unique solvents, often used as 'green' alternatives to traditional solvents.

Energy efficiency in chemical processes

Minimizing energy consumption during chemical reactions, considering environmental and economic factors.

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Microwave irradiation

Using microwaves to speed up chemical reactions or increase yields.

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N-alkylation of azaheterocycles

A process of adding alkyl groups to nitrogen atoms in specific heterocyclic compounds (like pyrrole and imidazole).

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Ultrasound-assisted reactions

Using ultrasound waves to speed up reactions.

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Room temperature reactions

Performing chemical reactions at normal room temperature.

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Atom economy

A measure of how many atoms of the starting materials are incorporated into the final product in a chemical reaction.

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Green chemistry

A set of principles aimed at designing chemical products and processes to minimize the negative impact on human health and the environment.

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Less hazardous chemical syntheses

Chemical reactions designed to produce substances with reduced toxicity to humans and the environment.

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Designing safer chemicals

Designing products with reduced risk to human health and the environment.

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Thalidomide

A drug that was once prescribed for morning sickness but later found to be harmful during pregnancy, causing birth defects like phocomelia.

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Hazardous product

A chemical substance that is toxic or has a detrimental effect on the environment.

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Chemical synthesis

A process of creating new chemical compounds from existing ones.

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Leaving group

A part of a molecule that leaves during a chemical reaction.

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Biosensor Technology

A technology using biological systems to detect and measure substances.

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Lab-on-a-chip

Microfluidic analytical devices integrating multiple sample-handling processes with measurement on a microchip.

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Green Analytical Chemistry

Analytical techniques focused on reducing the environmental impact of chemical analysis.

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Capillary Electrophoresis/Electrochemistry (CE-EC) microchips

Microchips using capillary electrophoresis and electrochemistry for rapid separation and detection of pollutants.

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Priority Pollutants

Substances of significant environmental concern.

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Inherently Safer Chemistry

Chemical processes that minimize the risk of accidents.

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Oxidizing Agent

A substance that causes oxidation reactions.

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Micro-fabricated microfluidic devices

devices that combine microfluidic systems with analytical measurements, often on a microchip.

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Ionic liquids (containing BF4- or PF6- anions)

Ionic liquids that commonly contain BF4- or PF6- anions and are used in biphasic catalysis.

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Biphasic catalysis

A type of catalysis where reactants and products are primarily found in separate liquid phases.

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Non-nucleophilic

Doesn't readily attack other compounds in a chemical reaction.

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PEG (Polyethylene glycol)

A linear polymer, generally used in organic reactions, due to its low vapor pressure, thermal stability, biocompatibility, low toxicity, and easy removal from the reaction.

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Phase transfer catalysis

A type of catalysis where the catalyst transfers reactants between two liquid phases, like PEG being used in this method.

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Green alternative

An alternative to volatile organic solvents that are environmentally friendly and are also easy to separate.

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Low molecular weight PEG derivatives

PEGs with a molecular weight below 20,000, which are typically liquid at room temperature and are applied in organic reactions.

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Supercritical Carbon Dioxide (scCO2)

A substance that can be used for extracting reaction products from PEG or ionic liquids.

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ScCO2 in Polymerization

Supercritical carbon dioxide (ScCO2) is used as a solvent in polymerization reactions, particularly for cationic polymerization of isobutyl vinyl ether (IBVE).

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Heterogeneous Precipitation

In this process, the polymer formed during polymerization in ScCO2 precipitates out of the solution, creating a separate phase from the solvent.

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Lewis Acid & Base

In the polymerization of IBVE, a Lewis acid (ethylaluminum dichloride) and a Lewis base (ethyl acetate) are used to control the reaction.

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Diels-Alder in ScCO2

Diels-Alder reactions, a type of cycloaddition, have been studied extensively in ScCO2, particularly the reaction of maleic anhydride with isoprene.

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Pressure Effect on Rate

The rate of the Diels-Alder reaction in ScCO2 is affected by the pressure of CO2. Increasing pressure generally increases the reaction rate.

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Fluorous Biphasic System

A reaction system using two immiscible liquid phases, one containing a fluorous solvent and the other an organic solvent. Reactants and catalysts concentrate in the fluorous phase and products in the organic phase, allowing for easier separation and purification.

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Sonogashira Coupling

A specific type of organic reaction used to join a sp carbon (like in an alkyne) to an sp2 carbon (like in an aryl halide). It uses a palladium catalyst and copper co-catalyst.

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Supercritical Fluid

A substance that exists above its critical temperature and pressure, exhibiting properties between those of a liquid and a gas. It can dissolve materials and has unique transport properties.

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ScCO2

Supercritical carbon dioxide, a common and useful supercritical fluid due to its low cost, mild operating conditions, and environmental friendliness.

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Critical Temperature (Tc)

The temperature above which a substance cannot exist as a liquid, regardless of pressure. It marks the point where the liquid and gas phases become indistinguishable.

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Critical Pressure (Pc)

The minimum pressure required to liquefy a substance at its critical temperature. It's the pressure needed to overcome the tendency of a substance to vaporize.

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Advantages of Fluorous Solvents

Fluorous solvents can enhance reaction rates and selectivity, facilitate product separation, and enable catalyst recycling.

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Disadvantages of Fluorous Solvents

Fluorous solvents are often expensive to produce, require specialized equipment, and may have toxicity and environmental concerns.

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Study Notes

Introduction to Green Chemistry

  • Green Chemistry was introduced by Anastas in 1991.
  • The US Environmental Protection Agency (EPA) created a special program.
  • The program aimed at stimulating chemical and technological development.
  • The goal was to improve the outlook of chemists regarding environmental protection.
  • The approach focused on reducing or eliminating environmental and human health risks from chemical processes.

The Concept of Green Chemistry

  • Green chemistry emerged in the USA.
  • It stemmed from interdisciplinary cooperation between research groups.
  • This included universities, independent research groups, scientific societies, and government agencies.
  • Each group had its own program for reducing environmental pollution.
  • Green chemistry is a new approach to chemical substances, synthesis, processing, and applications.
  • It aims to reduce risks to human health and the environment.

12 Principles of Green Chemistry

  • Proposed by Anastas and Warner.
  • Guidance for creating new chemicals, syntheses, and technological processes.
  • Focuses on preventing waste, using renewable resources, and minimizing toxicity.

Prevention

  • Waste formation is better prevented than cleaning it up later/
  • Chemical procedures should strive to avoid waste.
  • Waste prevention is prioritized over cleanup and waste management in chemical methods.
  • "Grinding chemistry" is an example, where reagents are mixed without solvents.
  • Microwave irradiation is a growing area for solventless chemical processes.

Atom Economy

  • Chemical reactions should ideally use all the starting materials in the final product.
  • Aiming for 90%+ yield of desired product.
  • Ideal reactions ideally use all atoms to create desired product.
  • Any leftover unreacted atoms are considered waste.

Less Hazardous Chemical Syntheses

  • Chemical syntheses should be designed to use substances that pose little or no toxicity to human health and the environment.
  • Using less hazardous substances during chemical syntheses.

Designing Safer Chemicals

  • Design of chemical products, including drugs, should consider human health and environmental safety.
  • This principle aims at risk assessment of chemical products.
  • A real example is Thalidomide, a drug that caused birth defects in pregnant women.

Safer Solvents and Auxiliaries

  • Solvent selection should minimize environmental and health hazards.
  • Using ionic liquids or supercritical CO2 is ideal.
  • Choosing solvents that avoid harmful byproducts, are non-volatile, easily recycled, and non-toxic.

Energy Efficiency

  • Aim to reduce energy consumption in chemical processes.
  • Use of more energy-efficient chemical reactions.
  • The preferred temperatures for reactions are often ambient temperatures with lower possible temperatures/
  • Favoring techniques such as microwave irradiation.

Use of Renewable Feedstocks

  • Using renewable starting materials is preferable to using non-renewable ones like oil.
  • This promotes sustainability and can reduce the dependence on finite resources.
  • An example of a renewable feedstock is biodiesel which is produced from vegetable oils/ animal fats.

Design for Degradation

  • Chemical products should be designed to break down into harmless substances after their use/
  • This principle encourages environmentally friendly products that do not persist in the environment.
  • This includes promoting the use of biodegradable polymers.

Real-Time Analysis for Pollution Prevention

  • Aim to monitor chemical processes in real time to prevent the formation of harmful products.
  • Employing analytical tools and methodologies during the reaction, close to the production process/
  • Use of sensors in production facilities and in the field.

Inherently Safer Chemistry for Accident Prevention

  • Chemical processes to be designed with caution in case of accident events and avoiding the release of hazardous substances.
  • Use of safe reagents that limit negative environmental or health impacts.

Green Solvents

  • The choice of organic solvents should be carefully considered in chemical synthesis.
  • Volatile organic solvents, which are harmful to the environment, should be avoided if possible.
  • Use of environmentally friendly safer and less hazardous alternatives.
  • Employing water, ionic liquids, or supercritical carbon dioxide (scCO2) in reactions whenever possible.

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Chapter 2: 12 Principles of Green Chemistry PDF

Description

Discover the essentials of Green Chemistry, a pivotal field aimed at reducing environmental and health risks in chemical processes. Learn about its origins, key principles, and the collaborative efforts that shaped its development. This quiz also covers the 12 Principles of Green Chemistry proposed by Anastas and Warner.

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