Ethylenediamine (en) is a small, versatile bidentate diamine with the molecular formula C2H8N2, widely studied in coordination chemistry and pharmaceutical sciences. For B. Pharm students, understanding the structure and uses of ethylenediamine is essential: it forms stable five‑membered chelate rings with metal ions, influences ligand exchange, and serves as an intermediate in synthesis of chelating agents (like EDTA), drug intermediates, and formulation additives. Key topics include bonding, basicity, reactivity (acylation, alkylation), coordination behavior, toxicity and safe handling. This focused set of questions reinforces both theoretical concepts and practical implications for pharmaceutical applications. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the molecular formula of ethylenediamine?
- C2H8N2
- C2H7N2
- C3H8N2
- C2H6N2
Correct Answer: C2H8N2
Q2. How many donor atoms does ethylenediamine provide when acting as a ligand?
- One donor atom
- Two donor atoms
- Three donor atoms
- Four donor atoms
Correct Answer: Two donor atoms
Q3. What type of ligand is ethylenediamine in coordination chemistry?
- Monodentate ligand
- Bidentate ligand
- Tridentate ligand
- Tetradentate ligand
Correct Answer: Bidentate ligand
Q4. What size chelate ring is formed when ethylenediamine coordinates to a metal center through both nitrogen atoms?
- Three‑membered ring
- Four‑membered ring
- Five‑membered ring
- Six‑membered ring
Correct Answer: Five‑membered ring
Q5. Compared to ammonia, ethylenediamine is generally:
- Less basic
- Equally basic
- More basic
- Nonbasic
Correct Answer: More basic
Q6. Which functional groups are present in ethylenediamine?
- Two primary amine groups
- One primary amine and one secondary amine
- Two secondary amine groups
- One tertiary amine group
Correct Answer: Two primary amine groups
Q7. Ethylenediamine acts as a precursor in the synthesis of which common chelating agent?
- Citric acid
- Ethylenediaminetetraacetic acid (EDTA)
- Acetylacetone
- Dimercaprol
Correct Answer: Ethylenediaminetetraacetic acid (EDTA)
Q8. In pharmaceutical contexts, ethylenediamine derivatives are often used as:
- Solvent only
- Curing agent for polymers only
- Intermediates in drug synthesis and chelating agents
- Flavoring agents
Correct Answer: Intermediates in drug synthesis and chelating agents
Q9. Which property of chelate complexes formed by ethylenediamine is most notable?
- Lower solubility than monodentate complexes
- Decreased stability compared to monodentate ligands
- Increased thermodynamic stability due to the chelate effect
- Formation of unstable radicals
Correct Answer: Increased thermodynamic stability due to the chelate effect
Q10. Which reaction is ethylenediamine most likely to undergo at its nitrogen atoms?
- Electrophilic aromatic substitution
- Acylation to form amides
- Diels–Alder reaction
- Friedel–Crafts alkylation
Correct Answer: Acylation to form amides
Q11. The term “en” in coordination complexes (e.g., [Co(en)3]3+) refers to:
- Ethyl nitrite
- Ethylenediamine
- Ethanolamine
- Ethylamine
Correct Answer: Ethylenediamine
Q12. Which statement about ethylenediamine’s geometry when free (not bound) is correct?
- It is planar around both nitrogens
- The N–C–C–N backbone is flexible, allowing gauche conformations
- It always adopts a rigid trans conformation
- It is aromatic
Correct Answer: The N–C–C–N backbone is flexible, allowing gauche conformations
Q13. Ethylenediamine is classified as which type of organic compound?
- Alcohol
- Amine
- Carboxylic acid
- Aldehyde
Correct Answer: Amine
Q14. In coordination complexes, ethylenediamine is best described as which donor type?
- Soft donor
- Hard donor (nitrogen donors are relatively hard)
- Pi-acid donor
- Non‑donor
Correct Answer: Hard donor (nitrogen donors are relatively hard)
Q15. Which safety precaution is most appropriate when handling ethylenediamine in the lab?
- No precautions needed, it is inert
- Use gloves and eye protection due to corrosive and irritant properties
- Store in open containers at room temperature
- Only avoid light exposure
Correct Answer: Use gloves and eye protection due to corrosive and irritant properties
Q16. Ethylenediamine forms strong complexes with transition metals because:
- It donates electrons via oxygen atoms
- It is a bidentate ligand that reduces entropy loss on complexation and forms stable rings
- It is highly bulky and forces metal coordination
- It cannot form chelate rings
Correct Answer: It is a bidentate ligand that reduces entropy loss on complexation and forms stable rings
Q17. Which of the following is a common industrial use of ethylenediamine?
- Fuel additive only
- Intermediate for agrochemicals, pharmaceuticals, and chelating agents
- Food preservative
- Flavor enhancer
Correct Answer: Intermediate for agrochemicals, pharmaceuticals, and chelating agents
Q18. Which analytical technique is most useful to confirm coordination of ethylenediamine to a metal center?
- IR spectroscopy showing shifts in N–H vibrations and metal–ligand bands
- Refractive index measurement only
- Simple pH paper test
- UV‑vis is never useful for such complexes
Correct Answer: IR spectroscopy showing shifts in N–H vibrations and metal–ligand bands
Q19. Protonation of ethylenediamine yields:
- A neutral species with no charge
- A mono‑ or di‑protonated ammonium species depending on pH
- A radical cation only
- An anion
Correct Answer: A mono‑ or di‑protonated ammonium species depending on pH
Q20. Which electrophile reacts readily with ethylenediamine at the nitrogen atoms?
- Acyl chlorides forming amides
- Alkanes under inert conditions
- Noble gases
- Unactivated alkenes without catalyst
Correct Answer: Acyl chlorides forming amides
Q21. Ethylenediamine’s two nitrogen atoms are separated by how many carbon atoms?
- Zero
- One
- Two
- Three
Correct Answer: Two
Q22. Which is true about ethylenediamine derivatives in drug design?
- They are never used due to toxicity
- They serve as linkers and scaffolds for multi‑functional drugs
- They only act as final active drugs without modification
- They cannot be functionalized at nitrogen
Correct Answer: They serve as linkers and scaffolds for multi‑functional drugs
Q23. The presence of two adjacent nitrogen donors in ethylenediamine primarily enhances complex stability via:
- Hydrogen bonding only
- Entropic and enthalpic contributions of chelation
- Electrostatic repulsion
- Decreased orbital overlap
Correct Answer: Entropic and enthalpic contributions of chelation
Q24. Which synthetic transformation converts ethylenediamine into a diacetamide derivative?
- Hydrogenation with Pd/C
- Acylation with acetic anhydride
- Oxidation with KMnO4
- Photolysis
Correct Answer: Acylation with acetic anhydride
Q25. In acid–base titrations, ethylenediamine typically shows:
- Only one equivalence point
- Two equivalence points corresponding to two protonatable amine sites
- No protonation behavior
- Three equivalence points
Correct Answer: Two equivalence points corresponding to two protonatable amine sites
Q26. Which physical property of ethylenediamine affects its use as a solvent or reagent?
- High volatility with no boiling point
- Relatively high polarity and hydrogen‑bonding ability
- Complete insolubility in water
- Being a nonpolar hydrocarbon
Correct Answer: Relatively high polarity and hydrogen‑bonding ability
Q27. Ethylenediamine binds to metal centers through which atom type?
- Oxygen atoms
- Nitrogen atoms
- Sulfur atoms
- Phosphorus atoms
Correct Answer: Nitrogen atoms
Q28. Which statement about enantiomerism for simple ethylenediamine itself is correct?
- Ethylenediamine is inherently chiral
- Free ethylenediamine is achiral, but complexes can be chiral
- It always exists as a racemic mixture
- It has restricted rotation causing atropisomerism
Correct Answer: Free ethylenediamine is achiral, but complexes can be chiral
Q29. Which reagent is commonly used to protect amine groups of ethylenediamine during synthesis?
- Silylation agents (e.g., TMS‑Cl)
- Boc anhydride or carbamate protecting groups
- Chromic acid
- Strong base only
Correct Answer: Boc anhydride or carbamate protecting groups
Q30. Which effect explains the enhanced stability of metal complexes with ethylenediamine compared to two separate monodentate amines?
- Inductive effect
- Chelate effect
- Mesomeric effect
- Hyperconjugation
Correct Answer: Chelate effect
Q31. Ethylenediamine is most likely to be stored under which conditions for safety?
- Open to air at high temperature
- In tightly closed containers, away from acids and oxidizers
- Mixed with strong acids to stabilize it
- Exposed to sunlight on a bench
Correct Answer: In tightly closed containers, away from acids and oxidizers
Q32. In a complex [Ni(en)3]2+, how many ethylenediamine ligands are coordinated?
- One
- Two
- Three
- Six
Correct Answer: Three
Q33. Which of the following best describes ethylenediamine’s role in EDTA synthesis?
- It is a solvent for EDTA only
- It provides the diamine backbone for tetracarboxylation to EDTA
- It is a final chelating product identical to EDTA
- It degrades EDTA
Correct Answer: It provides the diamine backbone for tetracarboxylation to EDTA
Q34. Which spectroscopic change would indicate coordination of ethylenediamine to a metal?
- No change in any spectra
- Shifts in N–H stretching frequencies and new metal–nitrogen bands in IR
- Loss of all signals in NMR
- Appearance of strong C=O bands
Correct Answer: Shifts in N–H stretching frequencies and new metal–nitrogen bands in IR
Q35. Which toxicity concern is associated with ethylenediamine relevant to B. Pharm students?
- It is completely non‑toxic and safe to ingest
- It can be a skin sensitizer and respiratory irritant requiring careful handling
- It is a known nutrient with no hazards
- It explodes on contact with air
Correct Answer: It can be a skin sensitizer and respiratory irritant requiring careful handling
Q36. Which type of drug formulation role could ethylenediamine derivatives play?
- Active pharmaceutical ingredient only
- Buffering agent, complexing agent, or synthetic intermediate
- Flavoring agent in syrups
- Tablet colorant only
Correct Answer: Buffering agent, complexing agent, or synthetic intermediate
Q37. Which reaction type can convert ethylenediamine into a cyclic imine under appropriate conditions?
- Condensation with aldehydes/ketones (Schiff base formation) followed by cyclization
- Direct hydrogenation without catalyst
- Reductive ozonolysis
- Nucleophilic aromatic substitution
Correct Answer: Condensation with aldehydes/ketones (Schiff base formation) followed by cyclization
Q38. Which property makes ethylenediamine a good ligand for stabilizing metal ions in solution?
- Lack of lone pairs on nitrogen
- The presence of lone pairs on both nitrogen atoms allowing chelation
- Its extreme bulk preventing binding
- Its inability to form hydrogen bonds
Correct Answer: The presence of lone pairs on both nitrogen atoms allowing chelation
Q39. Which is a common method to quantify ethylenediamine content in a sample?
- Titration with standard acid and pH monitoring
- Simple weighing without analysis
- Color test for aldehydes
- Measuring refractive index only
Correct Answer: Titration with standard acid and pH monitoring
Q40. In metal complex nomenclature, how is ethylenediamine denoted?
- en
- eda
- eth
- edta
Correct Answer: en
Q41. Which of the following is TRUE about ethylenediamine’s solubility?
- It is insoluble in water
- It is miscible or highly soluble in water due to hydrogen bonding
- It dissolves only in nonpolar solvents
- It sublimes at room temperature
Correct Answer: It is miscible or highly soluble in water due to hydrogen bonding
Q42. Which pharmaceutical process might utilize ethylenediamine as an intermediate?
- Synthesis of antihistamine linkers or heterocyclic scaffolds
- Direct formulation of vitamins
- Color matching in tablet coatings
- Evaporation to dryness only
Correct Answer: Synthesis of antihistamine linkers or heterocyclic scaffolds
Q43. Which condition would protonate ethylenediamine to the diprotonated form?
- Strongly basic pH
- Neutral pH
- Strongly acidic pH
- Anhydrous benzene
Correct Answer: Strongly acidic pH
Q44. Which metal ion commonly forms stable complexes with ethylenediamine?
- Alkali metals like Na+ only
- Transition metals such as Cu2+, Ni2+, Co2+
- Noble gases
- Halide ions
Correct Answer: Transition metals such as Cu2+, Ni2+, Co2+
Q45. Which laboratory technique can separate ethylenediamine from a reaction mixture based on volatility?
- Distillation
- Paper chromatography only
- Magnetic separation
- Counter‑current electrophoresis
Correct Answer: Distillation
Q46. The basicity difference between the two nitrogen atoms in ethylenediamine is primarily due to:
- Large differences in electronegativity between the nitrogens
- Intramolecular hydrogen bonding and mutual electron donation effects
- Presence of aromaticity
- Metal coordination exclusively
Correct Answer: Intramolecular hydrogen bonding and mutual electron donation effects
Q47. Which degradation or hazard is associated with ethylenediamine storage if contaminated with strong oxidizers?
- Enhanced stability and inertness
- Risk of exothermic reaction or decomposition
- Immediate polymerization to harmless wax
- No interaction
Correct Answer: Risk of exothermic reaction or decomposition
Q48. Which type of drug molecule commonly contains ethylenediamine-derived linkers?
- Small molecule drugs requiring bifunctional linkers and flexibility
- Inorganic salts only
- Purely lipidic drugs
- Metallic implants
Correct Answer: Small molecule drugs requiring bifunctional linkers and flexibility
Q49. Which statement best reflects ethylenediamine’s role in chelation therapy?
- Ethylenediamine itself is widely used as a chelation therapy drug
- Derivatives and related chelating agents (e.g., EDTA) are used to sequester metal ions
- It is never related to chelation agents
- It is used to supply metal ions in therapy
Correct Answer: Derivatives and related chelating agents (e.g., EDTA) are used to sequester metal ions
Q50. When designing formulations, why might a pharmacist consider ethylenediamine derivatives?
- To increase volatility of formulations
- To modulate solubility, chelate metals, or provide linker functionality in prodrugs
- To reduce all reactivity in the mixture
- To act as an inert filler
Correct Answer: To modulate solubility, chelate metals, or provide linker functionality in prodrugs
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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