Organic Synthesis

Chemistry, HSSC-Punjab Second Year. This chapter is split into 21 topics and has 500 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. FGI of alkenes, halogenoalkanes and alcohols 25 questions
2. Criteria of a good synthesis and overall yield 24 questions
3. Retrosynthesis and synthesis of ethyl ethanoate 25 questions
4. Quick Check items and synthons in Unit 25 24 questions
5. Retrosynthesis of aspirin 25 questions
6. Terminology and worked examples of retrosynthesis 23 questions
7. Planning multi-step syntheses 25 questions
8. Retrosynthesis of paracetamol 25 questions
9. Synthesis of aspirin and numericals 22 questions
10. Artificial intelligence in drug design and Halicin 25 questions
11. FGI and carbon-carbon bond formation 24 questions
12. FGI of aromatic compounds (Figure 25.4) 26 questions
13. Reaction types and by-products in synthetic steps 23 questions
14. Exercise MCQs of Unit 25 21 questions
15. Synthesis and retrosynthesis 23 questions
16. Functional groups and the concept of synthesis 25 questions
17. FGI by oxidation, reduction and acid derivatives 25 questions
18. Exercise short and descriptive questions of Unit 25 23 questions
19. Synthesis of paracetamol and numericals 21 questions
20. Designing syntheses from benzene 24 questions
21. Identifying functional groups and predicting properties 22 questions

Sample questions: Organic Synthesis

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. The compound used as the central starting point in Figure 25.4 is

From your book: Figure 25.4 (page 137) Full page Open book

• A. benzene(correct answer)
• B. aniline
• C. phenol
• D. toluene

Answer: A.Benzene is at the centre, with arrows leading to toluene, nitrobenzene, acetophenone and benzenesulfonic acid.

Q2. Which statement about the retrosynthetic arrow and the synthetic arrow is correct?

• A. they both mark a reversible reaction
• B. they point in opposite directions(correct answer)
• C. they are the same symbol in all books
• D. they both mark the use of a catalyst

Answer: B.The retrosynthetic arrow points from the TM to its precursors; the synthetic arrow points toward the TM.

Q3. The past few decades have seen the development of

• A. no antibiotics at all
• B. a very large number of new antibiotics
• C. very few new antibiotics(correct answer)
• D. only antiviral drugs

Answer: C.The book says few new antibiotics were developed and those were slightly different from existing ones.

Q4. The best order for making 4-nitrotoluene from benzene is

• A. sulfonation first, then alkylation
• B. alkylation first, then nitration(correct answer)
• C. nitration first, then alkylation
• D. oxidation first, then nitration

Answer: B.CH₃ directs the nitro group to the para (and ortho) position; nitrobenzene resists Friedel–Crafts alkylation (standard knowledge).

Q5. The chlorine substituent is an

• A. ortho/para director and deactivating group(correct answer)
• B. meta director and deactivating group
• C. meta director and activating group
• D. ortho/para director and activating group

Answer: A.Chlorine withdraws electrons by the −I effect but donates a lone pair by resonance (standard knowledge).

Q6. Phenylamine can be converted to phenol via

• A. toluene then warm water
• B. benzoic acid then warm water
• C. the diazonium salt then warm water(correct answer)
• D. nitrobenzene then warm water

Answer: C.Phenylamine is diazotised with NaNO₂/HCl in the cold and then warmed with water to give phenol (Unit 24).

Q7. The retrosynthesis of propyl ethanoate would give the starting materials

• A. propanoic acid and methanol
• B. ethanoic acid and propan-1-ol(correct answer)
• C. propanoic acid and ethanol
• D. ethanoic acid and propan-2-ol

Answer: B.Propyl ethanoate, CH₃COOCH₂CH₂CH₃, disconnects at the ester C−O bond into ethanoic acid and propan-1-ol.

Q8. A neutral solution of the aspirin product gives a violet colour with FeCl₃ only if unreacted

• A. free salicylic acid (a phenol)(correct answer)
• B. unreacted acetic anhydride
• C. traces of acetic acid
• D. the aspirin product itself

Answer: A.Phenols give a violet colour with iron(III) chloride; aspirin has no free phenolic OH (standard knowledge).

Q9. In the sequence phenol → nitrophenol (nitration) → aminophenol (reduction) → paracetamol (acetylation), how many functional group conversions occur before the last step?

• A. one: nitration only
• B. three: nitration, reduction, acylation
• C. none: no change of group
• D. two: nitration, then reduction(correct answer)

Answer: D.Phenol is nitrated to 4-nitrophenol, then reduced to 4-aminophenol; acetylation is the final step giving paracetamol.

Q10. One advantage of retrosynthesis is that

• A. complex targets become simple starting materials(correct answer)
• B. reagents are no longer needed
• C. the target becomes more expensive to make
• D. every molecule becomes explosive

Answer: A.Retrosynthesis makes complex target structures appear simple and achievable by working back to simple starting materials.