MCH-019 Solved Assignment January 2026 | GREEN CHEMISTRY | IGNOU MSCCHEM

Q1. List the twelve principles of green chemistry.

Key Points:

Prevention: Prioritize preventing waste over treating or cleaning it.
Atom Economy: Maximize reactant incorporation into the final product.
Safer Chemistry: Design processes and chemicals to minimize toxicity.
Energy Efficiency: Minimize energy use, preferably at ambient conditions.

Answer: Green chemistry, as elucidated in MCH-019, provides a framework of twelve fundamental principles guiding the design of chemical products and processes to reduce or eliminate hazardous substances. These principles serve as a cornerstone for pollution prevention and fostering environmentally benign chemical practices. 1. **Prevention**: It is better to prevent waste generation than to treat or clean up waste after it has been formed, emphasizing waste minimization at the source. 2. **Atom Econ...

Q2. Explain the principle of using safer solvents and auxiliaries.

Key Points:

Green Chemistry Principle 5: Use safer solvents and auxiliaries.
Minimize or eliminate hazardous solvents and auxiliary substances.
Solvents are often largest mass component, contributing to waste.
Avoid toxic, flammable VOCs like benzene or halogenated solvents.

Answer: The principle of using safer solvents and auxiliaries, enshrined as the fifth principle of Green Chemistry, mandates minimizing or eliminating the use of hazardous substances in chemical processes. Solvents and other auxiliary agents, such as separation agents, often constitute the largest mass component of a reaction mixture, thereby contributing substantially to waste streams and environmental impact. This principle advocates for selecting solvents that are non-toxic, non-flammable, biodegrad...

Q3. Explain the terms-‘reaction yield' and 'atom economy'. How are these two different?

Key Points:

Reaction yield measures actual product obtained against theoretical maximum from limiting reactant.
Reaction yield formula: (Actual Yield / Theoretical Yield) × 100%.
Atom economy measures how efficiently reactant atoms are incorporated into desired product.
Atom economy formula: (MW of Desired Product / Σ MW of All Reactants) × 100%.

Answer: In Green Chemistry, 'reaction yield' and 'atom economy' are crucial metrics for assessing synthetic efficiency, but they evaluate different aspects. Reaction yield, often expressed as a percentage, quantifies the efficiency of converting the limiting reactant into the desired product. It is calculated as the ratio of the actual amount of product obtained to the maximum theoretical amount that could be formed from the limiting reactant. The formula is: `Reaction Yield = (Actual Yield / Theoretic...

Q4. What aspects should be kept in mind while selecting a proper feedstock for synthesis from green chemistry point of view?

Key Points:

Prioritize renewable feedstocks (e.g., biomass) over non-renewable to reduce environmental impact (Principle 7).
Select feedstocks with inherently low hazard, toxicity, and flammability for safety (Principle 3).
Choose feedstocks maximizing atom incorporation into the final product to minimize waste (Atom Economy, Principle 2).
Evaluate the full lifecycle environmental impact, from sourcing to degradation, of the feedstock.

Answer: Selecting an appropriate feedstock for synthesis, from a green chemistry perspective, fundamentally aims to minimize environmental impact and maximize resource efficiency. A primary aspect involves prioritizing renewable raw materials, aligning with Principle 7 (Use of Renewable Feedstocks). This crucial shift reduces reliance on finite fossil resources, opting instead for sustainable alternatives such as biomass-derived compounds, thereby lowering the overall carbon footprint of chemical proces...

Q5. What are VOCs? Give examples. Explain various sources of VOCs.

Key Points:

VOCs are organic chemicals with high vapor pressure, easily evaporating into the atmosphere.
They have low boiling points and participate in atmospheric photochemical reactions.
Common examples include benzene, toluene, formaldehyde, and acetone.
Major anthropogenic sources are industrial solvents, paints, vehicle emissions, and fuel evaporation.

Answer: Volatile Organic Compounds (VOCs) are organic chemicals that have a high vapor pressure at ordinary room temperature. This high vapor pressure causes them to evaporate easily into the atmosphere, existing as gases. They are characterized by their low boiling points and their ability to participate in atmospheric photochemical reactions, contributing to air pollution. Examples of common VOCs include benzene, toluene, xylene, formaldehyde, acetone, and ethanol. These compounds are ubiquitous in v...

Q6. Explain various type of chemical reactions giving a suitable example for each.

Key Points:

Addition reactions combine molecules into one product, typically 100% atom-economical.
Substitution reactions replace groups, often generating byproducts and reducing atom economy.
Elimination reactions remove groups to form multiple products, leading to byproducts.
Rearrangement reactions involve atom reorganization within a molecule, usually byproduct-free.

Answer: Chemical reactions can be broadly classified based on how atoms rearrange, transform, or combine. Understanding these types is crucial in Green Chemistry, where atom economy and minimizing waste are key principles. While specific examples from the MCH-019 course PDF are not available, general chemistry provides clear illustrations. **1. Addition Reactions:** These reactions involve two or more molecules combining to form a single, larger molecule with no atoms left over. They are highly atom-ec...

Q7. When we search the literature available for a particular compound, what questions we should explore about it to know that it is a safe chemical.

Key Points:

Assess acute and chronic toxicity (e.g., LD₅₀, carcinogenicity, ecotoxicity).
Evaluate environmental persistence (biodegradability, environmental half-life).
Determine bioaccumulation potential (log P, Bioconcentration Factor - BCF).
Investigate physical hazards: flammability, explosivity, and reactivity.

Answer: To ascertain a compound's safety through a literature search, one must address its inherent hazards and environmental interactions comprehensively. This aligns with Green Chemistry principles, particularly "designing safer chemicals" (Principle 4) and "design for degradation" (Principle 10), ensuring a holistic evaluation beyond immediate toxicity. Crucial questions include: What is its acute (e.g., LD₅₀ value) and chronic toxicity (e.g., carcinogenicity, mutagenicity, teratogenicity) to humans...

Q8. Discuss various aspects of toxicity of a chemical to the humans to be considered while making a wiser choice from the available options.

Key Points:

Toxicity assessment is central to the Green Chemistry principle "Design safer chemicals."
Distinguish between acute (rapid) and chronic (prolonged exposure) toxicity effects.
Prioritize avoiding chemicals with carcinogenicity, mutagenicity, or teratogenicity (CMT).
Consider specific target organ toxicities like neurotoxicity, hepatotoxicity, nephrotoxicity.

Answer: When making wiser chemical choices, assessing potential human toxicity is fundamental, aligning with the Green Chemistry principle to "Design safer chemicals." This involves a comprehensive understanding of various hazardous properties that can impact human health, guiding the selection towards substances with inherently lower risk profiles. Key considerations include differentiating between acute toxicity, which causes rapid effects after short exposure, and chronic toxicity, arising from prol...

Q9. Illustrate how chemicals can harm and changes the local environment.

Key Points:

Chemicals disrupt natural environmental balances upon release.
Direct toxicity from pollutants harms local flora and fauna, reducing biodiversity.
Persistent chemicals (e.g., POPs) bioaccumulate and biomagnify through food webs.
Eutrophication, from nutrient runoff, depletes aquatic oxygen, killing fish.

Answer: Chemicals introduced into the local environment, through sources like industrial discharge, agricultural runoff, or improper waste disposal, can profoundly harm and alter natural ecosystems. These foreign substances disrupt delicate ecological balances and contaminate vital resources such as soil, water, and air. Many chemicals exert direct toxicity on local flora and fauna. For instance, heavy metals, including lead and mercury from industrial effluents, can poison aquatic life, while specific...

Q10. Discuss the harmful effects of global climate change.

Key Points:

Anthropogenic greenhouse gas emissions drive global temperature rise.
Melting glaciers and ice caps cause significant global sea level rise.
Coastal regions face increased flooding, erosion, and saltwater intrusion.
Climate change intensifies extreme weather events like heatwaves and droughts.

Answer: Global climate change, primarily driven by increased anthropogenic greenhouse gas emissions, poses severe and widespread harmful effects across environmental, social, and economic spheres. The core consequence is a significant rise in global average temperatures, leading to a cascade of destructive impacts. One major effect is the accelerated melting of glaciers and polar ice caps, directly contributing to a substantial rise in global sea levels. This phenomenon threatens coastal communities wi...

Q11. Explain the Boots synthesis of ibuprofen giving the chemical reactions involved.

Key Points:

Boots synthesis (BHC process) is a 3-step green route for ibuprofen.
First step: Friedel-Crafts acylation of isobutylbenzene using HF catalyst.
Second step: Catalytic hydrogenation of 4-isobutylacetophenone to an alcohol.
Third step: Carbonylation of the alcohol with CO, using a palladium catalyst.

Answer: The Boots synthesis, specifically the improved BHC (Boots-Hoechst-Celanese) process, is a renowned three-step green chemistry route for producing ibuprofen. It significantly reduces waste compared to the original six-step synthesis, achieving a high atom economy of approximately 77%. Step 1 involves the Friedel-Crafts acylation of isobutylbenzene. This reaction uses acetic anhydride as the acylating agent and hydrogen fluoride (HF) as a recyclable catalyst, producing 4-isobutylacetophenone and ...

Q12. Discuss the reactions involved in the greener synthesis of ibuprofen. Why is it greener as compared to Boots synthesis?

Key Points:

Greener ibuprofen synthesis (BHC process) has 3 steps; Boots synthesis has 6 steps.
BHC process involves acylation, hydrogenation, and catalytic carbonylation of alcohol.
Key greener reaction is catalytic carbonylation using CO and a palladium catalyst.
BHC process boasts ~77% atom economy, significantly higher than Boots' ~40%.

Answer: Ibuprofen, a widely used analgesic, has two main synthetic routes: the traditional Boots synthesis and the greener BHC (Hoechst Celanese) process. The BHC process exemplifies green chemistry principles by minimizing waste and enhancing efficiency. This greener approach significantly improves atom economy and reduces environmental impact compared to its predecessor. The greener BHC synthesis involves three key steps starting from isobutylbenzene. First, isobutylbenzene undergoes acylation with a...

Q13. Explain the importance of adipic acid. Write the scheme of its synthesis starting from benzene.

Key Points:

Adipic acid is a critical monomer for producing Nylon 6,6 polymer.
Nylon 6,6 is used in textiles, carpets, and engineering plastics for its strength.
Synthesis starts with catalytic hydrogenation of benzene to cyclohexane.
Cyclohexane is then oxidized using nitric acid to form adipic acid.

Answer: Adipic acid is a highly important dicarboxylic acid, crucial in polymer chemistry. Its primary significance lies in its role as a key monomer for the production of Nylon 6,6, a high-performance polyamide widely used in textiles, carpets, and engineering plastics due to its strength and durability. Beyond Nylon 6,6, adipic acid finds applications as a plasticizer, a component in polyurethanes, and even as a food additive (E355) for its tartness. Its substantial industrial demand underscores its ...

Q14. Discuss the harmful effects of the chemicals used in the above synthesis (Q.13) of adipic acid.

Key Points:

Nitric acid in adipic acid synthesis produces N₂O, a potent greenhouse gas.
N₂O contributes to stratospheric ozone depletion and global warming.
Nitrogen oxides (NOₓ) from nitric acid cause acid rain and photochemical smog.
Cyclohexane is a flammable VOC, often derived from carcinogenic benzene.

Answer: The traditional synthesis of adipic acid, often discussed in Green Chemistry courses as a non-green example, primarily involves the oxidation of cyclohexane using concentrated nitric acid. This process, as typically presented in Q.13 within MCH-019, utilizes chemicals with significant environmental and health drawbacks. One of the most harmful chemicals is nitric acid (HNO₃). Its use leads to the substantial production of nitrous oxide (N₂O), a potent greenhouse gas that is 310 times more effe...

Q15. What are antifoulants? Discuss the harmful effects of TBTO.

Key Points:

Antifoulants prevent marine organisms from attaching to submerged surfaces.
Tributyltin Oxide (TBTO) was a highly effective but toxic antifouling biocide.
TBTO causes imposex (male sexual organs in females) in marine gastropods.
Imposex leads to reproductive failure and population decline in affected snails.

Answer: Antifoulants are specialized chemical compounds applied as coatings to surfaces constantly immersed in water. Their primary function is to prevent the attachment and growth of aquatic organisms, known as fouling organisms, which include barnacles, algae, mussels, and other microorganisms. This process, called biofouling, can significantly reduce the efficiency of marine vessels, obstruct pipelines, and damage underwater structures, making antifoulants crucial for marine industries. Historically...

Q16. Explain the harmful effects of blowing agents used in the manufacturing of EPS.

Key Points:

CFCs/HCFCs, historical EPS blowing agents, caused severe stratospheric ozone depletion.
Ozone depletion by CFCs/HCFCs increased harmful UV radiation on Earth.
Current blowing agents like pentane are volatile organic compounds (VOCs).
VOC emissions from pentane contribute to ground-level ozone (smog) formation.

Answer: Expanded Polystyrene (EPS) manufacturing relies on blowing agents to create its characteristic foam structure. Historically, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) were widely used for this purpose. These earlier blowing agents, particularly CFCs and HCFCs, had significant harmful effects. They possessed a high Ozone Depletion Potential (ODP), meaning they chemically reacted with and destroyed the stratospheric ozone layer. This led to increased harmful ultraviolet (UV)...

Q17. What are the implications of using chlorine for obtaining white paper? Explain.

Key Points:

Chlorine (Cl₂) was historically used for bleaching wood pulp for white paper.
Chlorine reacts with lignin, forming highly toxic dioxins (PCDDs, PCDFs).
Dioxins are persistent organic pollutants (POPs) and bioaccumulate in food chains.
Dioxins are carcinogenic, mutagenic, teratogenic, and endocrine disruptors.

Answer: Historically, elemental chlorine (Cl₂) was a primary agent for bleaching wood pulp to achieve the desired whiteness for paper. Its mechanism involved reacting with and breaking down lignin, the natural binding agent in wood fibers, which also contained color-causing compounds. However, this process has significant environmental and health implications, leading to a shift towards greener alternatives. One major implication is the formation of highly toxic chlorinated organic compounds, particula...

Q18. Discuss the role of TAML activators in the bleaching of paper.

Key Points:

TAML activators are tetra-amido macrocyclic ligand iron(III) complexes.
They catalyze hydrogen peroxide (H₂O₂) to enhance its bleaching efficiency.
TAMLs activate H₂O₂ to selectively degrade lignin chromophores in pulp.
Their use replaces chlorine-based bleaching, reducing harmful AOX formation.

Answer: TAML activators, or tetra-amido macrocyclic ligand iron(III) complexes, play a crucial role in greening the paper bleaching process by serving as highly efficient catalysts. In traditional methods, chlorine-based chemicals lead to the formation of harmful Adsorbable Organic Halogens (AOX), posing significant environmental threats. TAML activators offer a sustainable alternative by enabling effective hydrogen peroxide (H₂O₂) bleaching. These activators function by significantly enhancing the oxi...

Q19. Explain the synthesis of PET starting from p-xylene. Write the reactions involved.

Key Points:

PET synthesis begins with the oxidation of p-xylene to terephthalic acid.
p-Xylene oxidation utilizes Co/Mn catalysts in acetic acid with oxygen.
Terephthalic acid (TPA) is a key monomer for PET production.
TPA reacts with ethylene glycol via polycondensation to form PET.

Answer: Polyethylene terephthalate (PET) synthesis from p-xylene involves a two-step process: first, the oxidation of p-xylene to terephthalic acid (TPA), and second, the polycondensation of TPA with ethylene glycol. This widely used polymer finds applications in bottles and fibers due to its robust properties. **Step 1: Oxidation of p-xylene to Terephthalic Acid (TPA)** Para-xylene is oxidized to terephthalic acid (TPA) using air or oxygen. This industrial process, often known as the Amoco process, ...

Q20. Discuss the application of green chemistry in the synthesis of drugs simvastatin, naproxen and aspirin. List some greener methods of synthesis being used these days in chemical laboratories.

(a)) Discuss the application of green chemistry in the synthesis of drugs simvastatin, naproxen and aspirin. (120 words)
(b)) List some greener methods of synthesis being used these days in chemical laboratories. (80 words)

Key Points:

Simvastatin's greener synthesis uses enzymatic resolution, avoiding hazardous organotin reagents.
Naproxen's greener production involves catalytic hydrogenation or supercritical CO2, reducing byproducts and solvent toxicity.
Aspirin's greener synthesis uses acetic acid with a catalyst, producing water instead of hazardous acetic anhydride.
Biocatalysis employs enzymes for highly selective, efficient reactions under mild conditions.

Answer: Green chemistry principles are vital in pharmaceutical synthesis, aiming to minimize waste, reduce hazard, and improve efficiency. This involves redesigning synthetic routes for key drugs like simvastatin, naproxen, and aspirin to align with principles such as atom economy, safer solvents, and catalysis. Modern laboratories are also adopting several greener methodologies to achieve sustainable chemical production. (a) The application of green chemistry in drug synthesis focuses on making proces...

MCH-019 Solved Assignment — January 2026 / July 2026

GREEN CHEMISTRY | IGNOU Master of Science in Chemistry Programme (MSCCHEM)

MCH-019—January 2026 / July 2026

GREEN CHEMISTRY

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MCH-019 Assignment Questions — January 2026

Q1. List the twelve principles of green chemistry.

Q2. Explain the principle of using safer solvents and auxiliaries.

Q3. Explain the terms-‘reaction yield' and 'atom economy'. How are these two different?

Q4. What aspects should be kept in mind while selecting a proper feedstock for synthesis from green chemistry point of view?

Q5. What are VOCs? Give examples. Explain various sources of VOCs.

Q6. Explain various type of chemical reactions giving a suitable example for each.

Q7. When we search the literature available for a particular compound, what questions we should explore about it to know that it is a safe chemical.

Q8. Discuss various aspects of toxicity of a chemical to the humans to be considered while making a wiser choice from the available options.

Q9. Illustrate how chemicals can harm and changes the local environment.

Q10. Discuss the harmful effects of global climate change.

Q11. Explain the Boots synthesis of ibuprofen giving the chemical reactions involved.

Q12. Discuss the reactions involved in the greener synthesis of ibuprofen. Why is it greener as compared to Boots synthesis?

Q13. Explain the importance of adipic acid. Write the scheme of its synthesis starting from benzene.

Q14. Discuss the harmful effects of the chemicals used in the above synthesis (Q.13) of adipic acid.

Q15. What are antifoulants? Discuss the harmful effects of TBTO.

Q16. Explain the harmful effects of blowing agents used in the manufacturing of EPS.

Q17. What are the implications of using chlorine for obtaining white paper? Explain.

Q18. Discuss the role of TAML activators in the bleaching of paper.

Q19. Explain the synthesis of PET starting from p-xylene. Write the reactions involved.

Q20. Discuss the application of green chemistry in the synthesis of drugs simvastatin, naproxen and aspirin. List some greener methods of synthesis being used these days in chemical laboratories.