VIDEOS

NOTES

ASSIGNMENT

Section A: Multiple Choice Questions (1 mark each)

1. Which of the following is a product of Wurtz reaction?
   a) Alkene
   b) Alkyne
   c) Alkane
   d) Alcohol
2. Which reagent gives elimination as the major product with 2-bromopentane?
   a) Aqueous KOH
   b) Alcoholic KOH
   c) KCN
   d) AgNO₃
3. SN1 mechanism is favored by:
   a) Primary halides
   b) Secondary halides
   c) Tertiary halides
   d) All halides equally
4. Which of the following reacts with haloarenes in Wurtz-Fittig reaction?
   a) Another aryl halide
   b) Sodium alkoxide
   c) Alkyl halide + Na
   d) Sodium nitrite
5. The elimination reaction of 2-bromobutane in alcoholic KOH gives:
   a) Butan-2-ol
   b) But-1-ene and But-2-ene
   c) Butane
   d) 2-chlorobutane

Section B: Assertion and Reason (1 mark each)

1. Assertion (A): Alcoholic KOH induces β-elimination in haloalkanes.
   Reason (R): The OH⁻ acts as a base and abstracts a proton.
2. Assertion (A): SN2 reactions are faster in primary alkyl halides.
   Reason (R): Less steric hindrance allows easy backside attack.
3. Assertion (A): Aryl halides do not easily undergo nucleophilic substitution.
   Reason (R): Resonance stabilization and partial double bond character in C–X bond.

Section C: One Word/One Line Answer (1 mark each)

1. Name the reaction: Alkyl halide + Na + Alkyl halide → Alkane.
2. What is the role of dry ether in Wurtz reaction?
3. What type of product is obtained when haloalkane reacts with alcoholic KOH?

Section D: Short Answer Questions (2 marks each)

1. Explain with an example the difference between SN1 and SN2 mechanisms.
2. Write a balanced chemical equation for the Wurtz-Fittig reaction and name the product.

Section E: Short Answer Question (3 marks)

1. Complete and write the products for the following reactions:
   (a) C₂H₅Br + alcoholic KOH → ?
   (b) Bromobenzene + CH₃Br + Na (in dry ether) → ?
   (c) C₂H₅Br + KCN → ?

KEY

Section A: Multiple Choice Questions

1. Answer: c) Alkane
2. Answer: b) Alcoholic KOH
3. Answer: c) Tertiary halides
4. Answer: c) Alkyl halide + Na
5. Answer: b) But-1-ene and But-2-ene

Section B: Assertion and Reason

1. Answer: a) Both Assertion and Reason are true, and Reason is the correct explanation.
2. Answer: a) Both Assertion and Reason are true, and Reason is the correct explanation.
3. Answer: a) Both Assertion and Reason are true, and Reason is the correct explanation.

Section C: One Word/One Line Answers

1. Answer: Wurtz reaction
2. Answer: Solvent and reaction medium for the sodium metal
3. Answer: Alkene (via β-elimination)

Section D: Short Answer Questions

1. Answer:
   – **SN1** is a two-step mechanism, involves carbocation intermediate, e.g., (CH₃)₃CBr → (CH₃)₃COH
   – **SN2** is a single-step backside attack with inversion, e.g., CH₃CH₂Br + OH⁻ → CH₃CH₂OH
2. Answer:
   C₆H₅Br + CH₃Br + 2Na → C₆H₅CH₃ + 2NaBr
   (This is the **Wurtz-Fittig reaction**; product is toluene)

Section E: Short Answer Question (3 Marks)

1. Answer:
   • (a) C₂H₅Br + alcoholic KOH → CH₂=CH₂ + HBr + H₂O (Ethene formed via β-elimination)
   • (b) C₆H₅Br + CH₃Br + 2Na → C₆H₅CH₃ + 2NaBr (Toluene via Wurtz-Fittig reaction)
   • (c) C₂H₅Br + KCN → C₂H₅CN + KBr (Ethyl cyanide via nucleophilic substitution)