Organic Nitrogen Compounds

Chemistry, HSSC-Punjab Second Year. This chapter is split into 30 topics and has 681 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Multi-step syntheses with nitrogen compounds 25 questions
2. Preparation of amides 23 questions
3. Preparation of primary amines 23 questions
4. Azo dyes and the chromophore 22 questions
5. Numericals on Kb, pKb and pH of amines 21 questions
6. Reagents and conditions for nitrogen compounds 24 questions
7. Nitriles: preparation and hydrolysis 22 questions
8. Importance of organic nitrogen compounds 23 questions
9. Coupling reactions and azo compounds 21 questions
10. Reaction of phenylamine with bromine water 21 questions
11. Properties and basicity of amides 22 questions
12. Structure of amino acids 23 questions
13. Ninhydrin and detection of amino acids 20 questions
14. Preparation of phenylamine 21 questions
15. Basicity of amines 23 questions
16. Nitrous acid tests on amines 24 questions
17. Numericals on nitrogen compounds 21 questions
18. Zwitterions and acid-base properties of amino acids 24 questions
19. Peptides and peptide bonds 25 questions
20. Isomerism of amines 23 questions
21. Classification of amines 24 questions
22. IUPAC naming of amines 21 questions
23. Relative basicity of ammonia, amines and phenylamine 23 questions
24. Diazotisation and diazonium salts 24 questions
25. Isoelectric point and electrophoresis 26 questions
26. Reactions of phenylamine: ring versus amino group 21 questions
27. Exercise questions of Unit 24 24 questions
28. Preparation of secondary amines 23 questions
29. Hofmann bromamide reaction 22 questions
30. Reactions of amides 22 questions

Sample questions: Organic Nitrogen Compounds

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

Q1. The IUPAC name of CH₃CH(CH₃)CH₂CH₂CH₂NH₂ is

• A. isohexylamine
• B. 2-methylpentan-1-amine
• C. 4-methylpentan-1-amine(correct answer)
• D. 3-methylhexan-1-amine

Answer: C.The chain has five carbons from C1 (CH₂NH₂); the methyl group is on C4. This is the structure in the book’s Quick Check 24.1(a)(i).

Q2. Primary, secondary and tertiary amines of the same molecular formula are examples of

• A. position isomers, with the same groups
• B. chain isomers, with the same groups
• C. functional isomers, with the same formula(correct answer)
• D. geometrical isomers, with a C=C bond

Answer: C.The book’s MCQ I answer: they are functional group isomers (the nitrogen has different numbers of alkyl groups).

Q3. How many methods for preparing aliphatic primary amines are listed in 24.2 A of the book?

• A. three
• B. five(correct answer)
• C. six
• D. four

Answer: B.Halogenoalkane + NH₃; reduction of nitriles; reduction of nitroalkanes; reduction of amides; the Hofmann reaction.

Q4. The nitrile, nitro compound and amide that each give 2-methylpropan-1-amine on reduction are, in order,

• A. (CH₃)₃CCN, (CH₃)₃CNO₂ and (CH₃)₃CCONH₂
• B. CH₃CH₂CH₂CN, CH₃CH₂CH₂CH₂NO₂ and CH₃CH₂CH₂CONH₂
• C. (CH₃)₂CHCN, (CH₃)₂CHCH₂NO₂ and (CH₃)₂CHCONH₂(correct answer)
• D. (CH₃)₂CHCH₂CN, (CH₃)₂CHCH₂NO₂ and (CH₃)₂CHCH₂CONH₂

Answer: C.The nitrile and amide have one carbon more than the nitro compound shares: the CN or CONH₂ carbon becomes the CH₂NH₂ carbon (book Quick Check 24.2b).

Q5. Secondary amines can be prepared by

• A. oxidation of primary alcohols with dichromate
• B. hydrolysis of nitriles with dilute acid
• C. hydration of alkenes with steam
• D. alkylation of primary amines with halogenoalkanes(correct answer)

Answer: D.The book states that a halogenoalkane with a primary amine under pressure in ethanol gives a secondary amine.

Q6. Why is the nitro route preferred for phenylamine in the retrosynthesis of Unit 25?

• A. NH₂ is a poor reducing agent for benzene
• B. NO₂ is a cheaper reagent than NH₂
• C. benzene dissolves in HNO₃ but not in NH₃
• D. NO₂ attaches by electrophilic substitution, NH₂ cannot(correct answer)

Answer: D.The book says it is easy to attach NO₂ on benzene by electrophilic substitution, rather than NH₂ by nucleophilic substitution.

Q7. How will you synthesise ethanal from ethanenitrile (book Q2 i)? A suitable route is

• A. heating with NaOH to give the aldehyde directly
• B. adding HCN across the C≡N bond
• C. oxidation of the nitrile with K₂Cr₂O₇
• D. partial reduction of the nitrile with a controlled hydride(correct answer)

Answer: D.Nitriles are reduced to aldehydes by a mild hydride (DIBAL-H) or by Stephen’s method; the book asks the question without giving the answer.

Q8. Why does coupling happen at the para position and not at the ortho positions of phenol?

• A. the ortho positions have the OH bonded to them
• B. the para position has a positive charge
• C. para attack is less hindered and the ring is activated there(correct answer)
• D. the ortho positions are deactivated

Answer: C.Both ortho and para are activated, but the large diazonium electrophile prefers the para position (standard knowledge).

Q9. Primary, secondary and tertiary amines are regarded as (exercise Q1 I)

• A. metamers differing in alkyl groups only
• B. tautomers that interconvert at once
• C. functional group isomers of the same formula(correct answer)
• D. position isomers of a single chain

Answer: C.The book’s answer to the first MCQ: they differ in the number of alkyl groups on nitrogen, giving functional isomers of the same molecular formula.

Q10. Which one of the following bases is the strongest (exercise Q1 III)?

• A. ethylamine
• B. ammonia
• C. diethylamine(correct answer)
• D. phenylamine

Answer: C.Diethylamine, a secondary amine, has two electron-releasing ethyl groups (the book’s options a, b, c, d list NH₃, ethylamine, phenylamine, diethylamine).