Chemistry Chapter 13 - Amines (PDF)

# **AMINES** ## **Chapter Outline** | **Topic** | **Page Number** | |---|---| | Important Methods and Reactions | 278 | | Exercises | 280 | | 13.1 Introduction and Classification of amines | 283 | | 13.2 Nomenclature of amines | 283 | | 13.2.1 Common names | 283 | | 13.2.2 IUPAC names | 291 | | 13...

# **AMINES** ## **Chapter Outline** | **Topic** | **Page Number** | |---|---| | Important Methods and Reactions | 278 | | Exercises | 280 | | 13.1 Introduction and Classification of amines | 283 | | 13.2 Nomenclature of amines | 283 | | 13.2.1 Common names | 283 | | 13.2.2 IUPAC names | 291 | | 13.3 Preparation of amines | 291 | | 13.3.1 By ammonolysis of alkyl halides | 291 | | 13.3.2 Reduction of nitro compounds | 291 | | 13.3.3 Reduction of alkyl cyanide (alkanenitriles) | 291 | | 13.3.4 By reduction of amides | 291 | | 13.3.5 Gabriel phthalimide synthesis | 291 | | 13.3.6 By Hofmann degradation (Hofmann rearrangement/Hofmann bromamid degradation/Hofmann hypobromite degradation) | 291 | | 13.4 Physical properties of amines | 299 | | 13.4.1 Intermolecular forces, boiling points and solubility | 299 | | 13.5 Basicity of amines | 301 | | 13.5.1 Basic strength of aliphatic amines | 301 | | 13.5.2 Basicity of arylamines | 304 | | 13.6 Chemical properties of amines | 304 | | 13.6.1 Laboratory test for amines | 304 | | 13.6.2 Alkylation of amines : Hofmann's exhaustive alkylation | 304 | | 13.6.3 Hofmann elimination | 304 | | 13.6.4 Acylation of amines | 304 | | 13.6.5 Carbylamine reaction | 304 | | 13.6.6 Reaction with nitrous acid | 304 | | 13.7 Reactions of arene diazonium salts | 312 | | 13.8 Reactions with arene sulphonyl chloride | 314 | | 13.9 Electrophilic aromatic substitution in aromatic amines | 321 | | Multiple Choice Questions | 334 | ## **Important Methods and Reactions** Amines are nitrogen containing organic compounds having basic character. **1. Classification of amines:** | **Type** | **Name** | **Formula** | **Examples Formula** | **Common Name** | |---|---|---|---|---| | Primary amine, (1°) | Amino | - NH2 | C2H5-NH2 | Ethylamine | | Secondary amine, (2°) | Imino | >NH | CH3 NH CH3 | Dimethylamine | | Tertiary amine, (3°) | Tertiary nitrogen | >N | CH3 CH3-N CH3 | Trimethylamine | **2. Methods of preparation and the reactions of primary amines:** - Ammonolysis of Alkyl Halides - Reduction of Nitro compounds - Reduction of Alkyl Cyanides (Alkanenitriles) - By reduction of amides - Gabriel phthalimide synthesis - By Hofmann degradation (Hofmann rearrangement/Hofmann bromamide degradation/ Hofmann hypobromite degradation) **3. Electrophilic aromatic substitution:** - 2,4,6 tribromoaniline - Acetanilide - p-Nitroaniline - m-Nitroaniline - o-Nitroaniline - Sulphanilic acid **4. Preparation and reactions of arene Diazonium salts:** | **Substrate** | **Reagent** | **Products** | **Title of reaction** | |---|---|---|---| | Ar-N2X | CuCl/HCl | Ar-Cl + N2 | Sandmeyer reaction | | Ar-N2X | CuBr/HBr | Ar-Br + N2 | | | Ar-N2X | CuCN/KCN | Ar-CN + N2 | | | Ar-N2X | Cu powder HCl | Ar-Cl + N2 | Gatterman reaction | | Ar-N2X | Cu powder HBr | Ar-Br + N2 | | | Ar-N2X | KI | Ar-I + N2 | Idodoarene formation | | Ar-N2Cl | H3PO2 | Ar-H + N2 + H3PO3 + HCl | Mild reduction | | Ar-N2Cl | H₂O CH3-CH2-OH | Ar-H + N2 + CH3CHO + HCI | | | Ar-N2Cl | H₂O 283 K | Ar-OH + N2 + HCI | Phenol formation | ## **Exercises** **Unit 13.1 Introduction and Classification of amines** - **Q. 1. What are amines?** - **Q. 2. How are amines classified?** - **Q. 3. Classify the following amines as primary, secondary and tertiary.** - **Q. 4. Mention the functional group in: (1) Primary amine (2) Secondary amine (3) Tertiary amine.** - **Q. 5. Write common and IUPAC names of following compounds :** - **Q. 6. Write the IUPAC names of the following amines :** - **Q. 7. Write IUPAC names of the following amines.** - **Q. 8. Give the structures of the following :** - **Q. 9. Give the IUPAC names of the following amines :** - **Q. 10. Write the IUPAC names of the following amines :** - **Q. 11. Give the structures and IUPAC names of the following amines :** - **Q. 12. Classify the following amines as primary, secondary and tertiary and write the IUPAC names.** - **Q. 13. Write the structures and classify the following amines as primary, secondary, tertiary amines.** - **Q. 14. Write the common and IUPAC name of a tertiary amine in which one methyl, one ethyl and one n-propyl group is attached to nitrogen.** ## **Unit 13.3 Preparation of amines** - **Q. 15. How will you prepare ethanamine from ethyl iodide?** - **Q. 16. Explain ammonolysis of alkyl halides.** - **Q. 17. How is a nitroalkane converted to a primary amine?** - **Q. 18. How will you prepare aniline from nitrobenzene?** - **Q. 19. Identify the compounds A and B in the following reactions:** - **Q. 20. How will you obtain a primary amine from an alkyl cyanide (nitrile)?** - **Q. 21. How will you prepare ethylamine from acetonitrile?** - **Q. 22. How will convert phenyl acetonitrile to ẞ-phenyl ethylamine?** - **Q. 23. How will you obtain primary amine from an acid amide?** - **Q. 24. How is ethyl amine obtained from phthalimide?** - **Q. 25. Explain Hoffmann degradation of amides.** - **Q. 26. How will you obtain methyl amine from acetamide?** - **Q. 27. How will you convert the following?** - **Q. 28. How will you prepare propan-1-amine from (1) butane nitrile (2) 1-nitropropane (3) propanamide (4) butanamide?** - **Q. 29. Write reaction to convert ethylamine into methyl amine.** - **Q. 30. Write reactions to prepare ethanamine from :** - **Q. 31. Identify A and B in the reactions:** - **Q. 32. Write a reaction to convert acetic acid into methyl amine.** ## **Unit 13.4 Physical properties of amines** - **Q. 33. Primary and secondary amines have boiling points higher than the tertiary amines. Explain why?** - **Q. 34. Amines have boiling points higher than the hydrocarbon but lower than the alcohols of comparable masses. Explain, why?** - **Q. 35. Arrange the following compounds in the decreasing order of their solubility in water.** - **Q. 36. Arrange the following compounds in the decreasing order of their boiling points.** ## **Unit 13.5 Basicity of amines** - **Q. 37. Explain the basic nature of amines with suitable example.** - **Q. 38. Tertiary amine (R3N) or 3º amine is weaker base than secondary amine R₂NH or 2º amine. Explain.** - **Q. 39. Primary or aliphatic amine is a stronger base than ammonia . Explain.** - **Q. 40. Aniline is less basic than ammonia. Explain.** - **Q. 41. Explain the order of basicity in ammonia and aliphatic amines.** - **Q. 42. Arrange the following amines in the decreasing order of their basic nature.** - **Q. 43. Arrange the following amines in the increasing order of their pK, values.** ## **Unit 13.6 Chemical properties of amines** - **Q. 45. Explain laboratory test for amines.** - **Q. 46. Explain Hofmann's exhaustive alkylation.** - **Q. 47. Predict the products of exhaustive methylation of following compounds.** - **Q. 48. Explain Hofmann elimination.** ## **Unit 13.4 Physical properties of amines** - **Q. 33. Primary and secondary amines have boiling points higher than the tertiary amines. Explain why?** - **Q. 34. Amines have boiling points higher than the hydrocarbon but lower than the alcohols of comparable masses. Explain, why?** - **Q. 35. Arrange the following compounds in the decreasing order of their solubility in water.** - **Q. 36. Arrange the following compounds in the decreasing order of their boiling points.** ## **Unit 13.5 Basicity of amines** - **Q. 37. Explain the basic nature of amines with suitable example.** - **Q. 38. Tertiary amine (R3N) or 3º amine is weaker base than secondary amine R₂NH or 2º amine. Explain.** - **Q. 39. Primary or aliphatic amine is a stronger base than ammonia. Explain.** - **Q. 40. Aniline is less basic than ammonia. Explain.** - **Q. 41. Explain the order of basicity in ammonia and aliphatic amines.** - **Q. 42. Arrange the following amines in the decreasing order of their basic nature.** - **Q. 43. Arrange the following amines in the increasing order of their pK, values.** ## **Unit 13.6 Chemical properties of amines** - **Q. 45. Explain laboratory test for amines** - **Q. 46. Explain Hofmann's exhaustive alkylation.** - **Q. 47. Predict the products of exhaustive methylation of following compounds.** - **Q. 48. Explain Hofmann elimination.** ## **Unit 13.7 Reactions of arene diazonium salts** - **Q. 61. Write a note on Sandmeyer's reaction.** - **Q. 62. How is aryl chloride or aryl bromide prepared by Gattermann reactions?** - **Q. 63. How is aryl iodide obtained from diazonium salt?** - **Q. 64. Explain the reduction of arene diazonium salt?** - **Q. 65. How is phenol obtained from arene diazonium salt?** - **Q. 66. How is aryl fluoride obtained from diazonium salt?** - **Q. 67. How is nitrobenzene obtained from benzene diazonium fluoroborate?** - **Q. 68. What is meant by a coupling reaction? Explain with suitable examples.** - **Q. 69. Explain Hinsberg's test.** ## **Unit 13.8 Reactions with arene sulphonyl chloride** - **Q. 70. What is the action of p-toluene sulphonyl chloride on ethyl amine and diethyl amine?** ## **Unit 13.9 Electrophilic aromatic substitution in aromatic amines** - **Q. 77. What is the action of aqueous bromine on aniline?** - **Q. 79. What is the action of acetic anhydride on aniline?** - **Q. 80. How will convert aniline to p-nitroaniline? (major product)** - **Q. 81. What is the action of conc. sulphuric acid on aniline?** ## **Unit 13.11 Reactions** - **Q. 82. How will you convert the following?** - **Q. 84. Write reactions to bring about the following conversions :** - **Q. 85. How will you convert :** - **Q. 86. Write reaction to convert :** - **Q. 87. How will you convert :** - **Q. 88. Complete the following reactions :** - **Q. 90. Identify B, C and D write complete reactions :** - **Q. 91. Identify the compounds B, C and D in the following series of reactions and rewrite the complete equations :** - **Q. 92. Identify the compounds ‘A’ and ‘B’ in the following equation :** - **Q. 93. Answer in one sentence :** ## **Unit 13.12** - **Q. 94. Select and write the most appropriate answer from the given alternatives for each subquestion :** ## **Unit 13.13** - **Q. 95. Why are aliphatic amines are stronger bases than ammonia?** - **Q. 96. Predict the product of the following reaction. Nitrobenzene Sn/conc. HCI ?** - **Q. 97. Write the IUPAC name of benzyl amine.** - **Q. 98. Arrange the following amines in an increasing order of boiling points n-propyl amine, ethyl methyl amine, trimethyl amine.** - **Q. 99. Write the balanced chemical equations for action of dil. H₂SO₄ on diethyl amine.** ## **Unit 13.14** - **Q. 100. Arrange the following amines in the increasing order of their „K, values. Aniline, cyclohexyl amine, 4-nitroaniline.** - **Q. 101. Arrange the following compounds in decreasing order of basic strength in their aqueous solutions. NH3, C2H5NH2, (CH3)2NH, (CH3)3N** - **Q. 102. Arrange the following compounds in an increasing order of their solubility in water.** - **Q. 103. What is Hinsberg's reagent?** - **Q. 104. Name the reaction in which a primary amine is formed from amide.** - **Q. 105. NH3 is a Lewis base.** - **Q. 106. How many primary amines are possible for the compound C3H,N?** - **Q. 107. State the hybridization of the nitrogen atom in amines.** - **Q. 108. Arrange the following compounds in an increasing order of basic strength. Aniline, p-nitroaniline, p-toluidine.** - **Q. 109. Which of the two is more basic and why? CH3NH2 or NH3** - **Q. 110. Which of the two is more basic and why? p-toluidine or aniline.** ## **Unit 13.15** - **Q. 111. What is diazotisation? Write diazotisation reaction of aniline.** ## **Unit 13.16** - **Q. 112. How is aryl chloride or aryl bromide or aryl cyanide prepared from diazonium salt?** - **Q. 113. How is aryl chloride or aryl bromide prepared by Gattermann reactions?** - **Q. 114. How is aryl iodide obtained from diazonium salt?** - **Q. 115. Explain the reduction of arene diazonium salt?** - **Q. 116. How is phenol obtained from arene diazonium salt?** - **Q. 117. How is aryl fluoride obtained from diazonium salt?** - **Q. 118. How is nitrobenzene obtained from benzene diazonium fluoroborate?** ## **Unit 13.17** - **Q. 120. Identify the compound B in the following series of reaction. Popanenitrile Na/Alc. NaNO2 A dil. HCl B** ## **Unit 13.18** - **Q. 121. What is the action of acetyl chloride on :** - **Q. 122. What is acetylation of amine?** ## **Unit 13.19** - **Q. 123. Explain carbyl amine test or isocyanide test.** - **Q. 124. Write the carbylamine reaction by using aniline as starting material.** ## **Unit 13.20** - **Q. 125. What is the action of nitrous acid on ethyl amine?** - **Q. 126. What is the action of nitrous acid on aniline?** - **Q. 127. How is benzenediazonium chloride prepared?** - **Q. 128. Write resonance stabilized structures of aryl diazonium salt.** ## **Unit 13.21** - **Q. 129. Give plausible explanation for each of the following statements :** ## **Unit 13.22** - **Q. 130. Complete the following reactions :** - **Q. 131. Identify the compounds ‘A’ and ‘B’ in the following equation :** ## **Unit 13.23** - **Q. 132. Identify the compounds B, C and D in the following series of reactions and rewrite the complete equations :** ## **Unit 13.24** - **Q. 133. Identify the compound ‘A' in the following reaction :** - **Q. 134. n-propyl alcohol is obtained when HNO₂ is treated with** ## **Unit 13.25** - **Q. 135. A mixture of CH3NH2, ( CH3) 2NH , (CH3) 3N can be distinguished by using** ## **Unit 13.26** - **Q. 136. In the acetylation reaction the H-atom of an amine is replaced by** ## **Unit 13.27** - **Q. 137. Amines are basic in nature** ## **Unit 13.28** - **Q. 138. The correct order of increasing basic strength is** - **Q. 139. Which of the following is the strongest base?** ##**Unit 13.29** - **Q. 140. Identify the weakest base amongst the following:** ## **Unit 13.30** - **Q. 141. Amine that cannot be prepared by Gabriel phthalimide synthesis is** - **Q. 142. Which of the following exist as Zwitter ion?** - **Q. 143. Reduction of benzene diazonium chloride with Zn/HCl gives** - **Q. 144. When primary amine reacts with CHCl3 in alcoholic KOH, the product is** - **Q. 145. Which of the following amines cannot be prepared by Gabriel phthalimide synthesis?** - **Q. 146. Which of the following compounds has highest boiling point?** - **Q. 147. Identify the statement about the basic nature of amines.** - **Q. 148. The compounds 'A', 'B' and 'C' react with methyl iodide to give finally quaternary ammonium iodides. Only 'C' gives carbylamines test while only 'A' forms yellow oily compound on reaction with nitrous acid. The compounds 'A', 'B' and 'C' are respectively.** - **Q. 149. Which of the following amines is most basic in nature?** - **Q. 150. How many moles of methyl iodide are required to convert ethylamine, diethylamine and triethylamine into quaternary ammonium salt, respectively?** - **Q. 151. Which of the following amines does not undergo acetylation?** - **Q. 152. n-Propylamine can be prepared by catalytic reduction of** - **Q. 153. Identify the compound 'B' in the following series of reactions :** - **Q. 154. Chloropicrin is used as** ## **Unit 13.31** - **Q. 155. Triethylamine when treated with nitrous acid gives** - **Q. 156. Amines are basic in nature because** - **Q. 157. An aqueous solution of primary amine contains** - **Q. 158. The basic nature of amines in an aqueous solution is in the order of** - **Q. 159. In trimethyl ammonium ion, the number of sigma bonds attached to nitrogen are** - **Q. 160. The number of coordinate bond/bonds in a trialkyl ammonium ion is** - **Q. 161. The number of electrons in the valence shell of nitrogen in methyl amine is** - **Q. 162. Ethanamine reacts with excess of acetyl chloride to form** - **Q. 163. The compound used for acylation of amine is .....** - **Q. 164. Dimethyl amine reacts with acetyl chloride to give** ##**Unit 13.32** - **Q. 165. Identify 'A' in the following reaction :** - **Q. 166. n-propyl alcohol is obtained when HNO2 is treated with** - **Q. 167. A mixture of CH3NH2, ( CH3) 2NH , (CH3) 3N can be distinguished by using** - **Q. 168. In the acetylation reaction the H-atom of an amine is replaced by** - **Q. 169. Amines are basic in nature** - **Q. 170. The correct order of increasing basic strength is** - **Q. 171. Which of the following is the strongest base?** - **Q. 172. Identify the weakest base amongst the following:** - **Q. 173. Amine that cannot be prepared by Gabriel phthalimide synthesis is** - **Q. 174. Which of the following exist as Zwitter ion?** - **Q. 175. Reduction of benzene diazonium chloride with Zn/HCl gives** - **Q. 176. When primary amine reacts with CHCl3 in alcoholic KOH, the product is** - **Q. 177. Which of the following amines cannot be prepared by Gabriel phthalimide synthesis?** - **Q. 178. Which of the following compounds has highest boiling point?** - **Q. 179. Identify the statement about the basic nature of amines.** - **Q. 180. The compounds 'A', 'B' and 'C' react with methyl iodide to give finally quaternary ammonium iodides. Only 'C' gives carbylamines test while only 'A' forms yellow oily compound on reaction with nitrous acid. The compounds 'A', 'B' and 'C' are respectively.** - **Q. 181. Which of the following amines is most basic in nature?** - **Q. 182. How many moles of methyl iodide are required to convert ethylamine, diethylamine and triethylamine into quaternary ammonium salt, respectively?** - **Q. 183. Which of the following amines does not undergo acetylation?** - **Q. 184. n-Propylamine can be prepared by catalytic reduction of** - **Q. 185. Identify the compound 'B' in the following series of reactions :** - **Q. 186. Chloropicrin is used as**