Pharmaceutical Organic Chemistry 3 Unit 4th Heterocyclic compounds

 1. Pyridine has a delocalised π molecular orbital containing:

• A. 4 electrons

• B. 8 electrons

• C. 6 electrons

• D. 12 electrons

Ans :- A

2. Which of the following compound is not a aromatic?

• A. Pyridine

• B. Furan

• C. Pyrrole

• D. Piperidine

Ans :- D

3. Pyridine is a planar compound?

• A. True

• B. False

Ans :- B

3. Pyridine is a planar compound?

• A. True

• B. False

Ans :- B

4. Pyrrole is less basic than pyridine because the lone pair of electrons on N atoms on pyridine_____________

• A. Is a part of a delocalised π molecular orbital.

• B. Is not a part of delocalised π molecule

• C. Resides in Sp2 hybrid orbital

• D. Resides in Sp hybrid orbital

Ans :- A

5. What is the smallest angle in pyridine ring?

• A. 116.7°

• B. 124.0°

• C. 115.0°

• D. 118.1°

Ans :- A

6. Which of the following alkaloids does not contain isoquinoline ring?

• A. Papaverine

• B. Narcotine

• C. Beriberine

• D. Aeriflavine

Ans :- D

7. Metronidazole, tinidazole contain which basic ring which can be used as an amoehicidal deep?

• A. Thiazole

• B. Imidazole

• C. Oxazole

• D. Pyrazole

Ans :- B

8. Midazolam, loprazolam contain which basic ring which can be used as an axoxiolytics?

• A. Imadazole

• B. Thiazole

• C. Oxazole

• D. Pyrazole

Ans :- A

9. Trimethoprim, sulphamethoxazole contain which of the following basic ring?

• A. Thiazole

• B. Pyrazole

• C. Oxazole

• D. Imidazole

Ans :- C

10. Imadazole on autoxidation gives _________

• A. Oxamide

• B. 4-carboxyl imidazole

• C. Imidazolodine

• D. All of the above

Ans :- A

11. Protonation of pyrazole gives __________

• A. Ring closure

• B. Ring opening

• C. Pyrazolium cation

• D. None of the above

Ans :- C

12. Rediszewski synthesis is used for the synthesis of __________

• A. Pyrazole

• B. Imadazole

• C. Thiazole

• D. Oxazole

Ans :- B

13. Debus prepared _____________ by reaction of glyoxal with ammonia.

• A. Pyrazole

• B. Thiazole

• C. Oxazole

• D. Imidazole

Ans :- D

14. Deprotanation of pyrazole at C-3 in the presence of strong base lead to:

• A. Ring closure

• B. Ring opening

• C. Pyrazolium cation

• D. None of the above

Ans :- B

15. Robinson-Gabriel synthesis is common method by the preparation of following compound ____________

• A. Imidazole

• B. Thiazole

• C. Oxazole

• D. Pyrazole

Ans :- C

16. How many number of resonating structure stabilises a pyridine molecules?

• A. 4

• B. 5

• C. 6

• D. 7

Ans :- B

17. Pyridine comes under which category of heterocycle classification of the basis of chemical behaviour?

• A. Excessive heterocycle

• B. Deficient heterocycle

• C. Equivalent heterocycle

• D. None of the above

Ans :- B

18. Electrophilic attacks in pyrazole is most favourably at the position _________

• A. C-4

• B. C-3

• C. C-4

• D. C-2

Ans :- A

19. Electrophilic substitutation of isoquinoline occurs at position _______

• A. 1

• B. 2

• C. 5

• D. 3

Ans :- C

20. Diphenylamine 2-carboxylic acid gives which of the following compound?

• A. Quinoline

• B. Isoquinoline

• C. Indole

• D. Acridine

Ans :- D

21. Pyridine react with HCL to form ________

• A. Pyridinium chloride

• B. Chloropyridine

• C. 3- Chloropyridine

• D. All of the above

Ans :- A

22. Pyridine undergoes nucleophilic substitution with NaNH2 at 100°C to form ____________

• A. 3- Amino pyridine

• B. 3- Nitro pyridine

• C. 4- Amino pyridine

• D. 2- Amino pyridine

Ans :- D

23. Pyridine react with a mixture of KNO3 and H2SO4 at 300°C to give ___________

• A. 1- Nitro pyridine

• B. 2- Nitro pyridine

• C. 3- Nitro pyridine

• D. 4- Nitro pyridine

Ans :- C

24. Pyridine undergoes electrophilic substitutation with fuming H2S04 at 350°C to give ___________

• A. 3- Pyridine sulphonic acid

• B. 2- Pyridine sulphonic acid

• C. 4- Pyridine sulphonic acid

• D. None of the above

Ans :- A

25. Indole ring is present in the following alkaloids:

• A. Ergot alkaloid

• B. Yohimbe alkaloid

• C. Harmala alkaloid

• D. All of the above

Ans :- D

26. Electrophilic substitutation reactions in indole occurs at position ___________

• A. 1

• B.2

• C. 3

• D. 4

Ans :- C

27. Nucleophilic substitution reactions in indole occurs at position ___________

• A. 1

• B. 2

• C. 3

• D. 4

Ans :- B

28. Nucleophilic substitution reactions in acridine occurs at position ___________.

• A. 1

• B. 2

• C. 3

• D. All of the above

Ans :- D

29.In acridine which of the following catalyst causes reduction of benzene ring?

• A. Zn/HCL

• B. Pt/HCL

• C. LiAlH4

• D. Both A and C

Ans :- B

30. In thiazole and oxazole nucleophile and electrophile attacks at _________

• A. C1 and C2 respectively

• B. C2 and C3 respectively

• C. C2 and C3 respectively

• D. C1 and C3 respectively

Ans :- C

31. The molecular formula of imidazole?

• A. C3H3N

• B. C3H3H2N

• C. C3H3HN2

• D. C3N2H4

Ans :- D

32. Which of the following statement is correct:

• A. Pyridine is primarily amine

• B. Pyridine is secondary amine

• C. Pyridine is neither primari nor a secondary amine

• D. None of the above

Ans :- C

33. Pyridine is basic in nature:

• A. Due to presence of lone pair of electrons on nitrogen atom

• B. Due to formation of salts with acid

• C. Due to formation of quaternary salt with alkyl halide

• D. All of the above

Ans :- D

34. Pyridine weaker base than aliphatic tertiary amine because………..

• A. Lone pair of electrons on nitrogen is sp2 hybridized

• B. Lone pair of electrons on nitrogen is sp3 hybridized

• C. Both A and B

• D. None of the above

Ans :- A

35. Pyridine is more basic than pyrolle because…………..

• A. Pyrolle is not having any lone pair of electrons for sharing

• B. Pyridine having lone pair of electrons for sharing

• C. Both A and B

• D. None of the above

Ans :- C

36. Pyridine shows low reactivity towards electrophilic substitutation reactions due to the…………

• A. Delocalised pi electrons

• B. Formation of pyridinilium ion in acidic condition

• C. All C-atom in pyridine ring are occupied

• D. Both A and B

Ans :- D

37. Which of the following catalyst is used for reduction of pyridine?

• A. H2/pt

• B. HI/Red P

• C. LiAlH

• D. All of the above

Ans :- D

38. Pyridine in absence of acid react with benzoyl peroxide to form…………..

• A. 2- phenyl pyridine

• B. 3- phenyl pyridine

• C. 4- phenyl pyridine

• D. Mixture of all of the above

Ans :- D

39. In Quinoline which of the ring is more electron rich?

• A. Nitrogen containing ring

• B. Carboxylic ring

• C. Both A and B

• D. None of the above

Ans :- B

40. Electrophilic substitutation reactions occurs in Quinoline at ………….

• A. Position 2 and 4

• B. Position 3 and 5

• C. Position 5 and 8

• D. Position 4 and 6

Ans :- C

41. Nitration of quinoline with nitric acid and acetic anhydride gives ______________

• A. 5 and 8 dinitro quinoline

• B. 2 and 4 dinitro quinoline

• C. 1 and 3 dinitro quinoline

• D. 3-nitroquinoline

Ans :- D

42. Vapour phase bromination of quinoline accours at …………

• A. 4 position

• B. 3 position

• C. 5 and 8 position

• D. 1 and 3 position

Ans :- B

43. In isoquinoline electrophilic substitutation reaction occurs at ………….

• A. Position 5 only

• B. Position 5 and 8

• C. Position 5 and 7

• D. Position 4 only

Ans :- B

44. Bromination and mercuration of isoquinoline occurs at ……….

• A. Position 5 only

• B. Position 5 and 8

• C. Position 4 only

• D. Position 4 and 8

Ans :- C

45. Nucleophilic attack in isoquinoline occurs at ………..

• A. Position 1

• B. Position 2

• C. Position 5 and 8

• D. Position 4

Ans :- A

46. Which of the ring in isoquinoline gets easily reduced?

• A. Benzene ring

• B. Nitrogen containing ring

• C. Both rings (A and B)

• D. None of the above

Ans :- B

47. In indole which of the heterocyclic ring is fused with benzene ring ___________

• A. Pyrazole

• B. Imadazole

• C. Isoxazole

• D. Pyrrole

Ans :- D

48. Pyridine in the presence of acid react with benzoyl peroxide and yield __________

• A. 2- phenyl pyridine

• B. 3- phenyl pyridine

• C. 4- phenyl pyridine

• D. Mixture of all of above

Ans :- A

49. Reduction of quinoline with H2/pt gives __________

• A. 1,2-dihydroquinoline

• B. 1,2,3,4-tetrahydroquinone

• C. Decahydroquinoline

• D. Nicotinic acid

Ans :- C

50. The molecular formula of Pyrazole?

• A. C3H6N2H

• B. C3H5N2H

• C. C3H5N3H

• D. C3H3N2H

Ans :- D.

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