18.1.2 Basicity of Amines

• What atom do amines contain that gives them their basic properties?

  Nitrogen
• Primary amines have the structure R-NH2
• Secondary amines are more basic than tertiary amines.
• What ion do amines form when they accept a proton?

  Ammonium ion
• Electronegative substituents reduce the basicity of amines.
• Rank the following factors affecting amine basicity from most significant to least significant:

  1️⃣ Steric hindrance

  2️⃣ Electronegativity of substituents

  3️⃣ Conjugation with aromatic rings
• Match the type of amine with its basicity:

  Primary Amines ↔️ Most basic

  Secondary Amines ↔️ Moderately basic

  Tertiary Amines ↔️ Least basic
• Why is methylamine more basic than aniline?

  Benzene ring reduces basicity
• Bulky substituents increase steric hindrance, which reduces amine basicity.
• The basicity of amines is affected by steric hindrance, electronegativity, and conjugation.
• How are amines classified based on their structure?

  Number of alkyl or aryl groups
• Steric hindrance from alkyl groups reduces the ability of amines to accept protons.
• Rank the basicity of primary, secondary, and tertiary amines from strongest to weakest:

  1️⃣ Primary amines

  2️⃣ Secondary amines

  3️⃣ Tertiary amines
• What is the primary factor that makes tertiary amines the least basic?

  Significant steric hindrance
• Match the factor affecting basicity with its effect:

  Electronegativity ↔️ Reduces basicity

  Steric hindrance ↔️ Hinders proton acceptance

  Conjugation ↔️ Decreases lone pair availability
• Aniline is less basic than methylamine due to the electron-withdrawing effect of the benzene ring.
• Amines are organic compounds containing a nitrogen atom with a lone pair of electrons
• Match the type of amine with its relative basicity:

  Primary Amines ↔️ Most basic

  Secondary Amines ↔️ Moderately basic

  Tertiary Amines ↔️ Least basic
• The basicity of amines is their ability to accept a proton (H+) to form an ammonium ion.
• The basicity of amines is affected by the electronegativity of substituents
• Why is methylamine more basic than aniline?

  Benzene ring reduces basicity
• Amines are classified as primary, secondary, or tertiary based on the number of alkyl or aryl groups attached to the nitrogen atom.
• What stabilizes the ammonium ion after protonation, enhancing basicity?

  Alkyl groups
• Methylamine is more basic than ethylamine due to the greater electron-donating effect of the ethyl group.

  False
• Steric hindrance increases with more alkyl groups, hindering proton acceptance
• Rank the basicity of primary, secondary, and tertiary amines from strongest to weakest:

  1️⃣ Primary Amines

  2️⃣ Secondary Amines

  3️⃣ Tertiary Amines
• What is the inductive effect of alkyl groups on amine basicity?

  Stabilizes the ammonium ion
• Substituents attached to an amine affect basicity by influencing the availability of the lone pair on the nitrogen atom.
• Match the substituent type with its effect on amine basicity:

  Electron-Donating Groups ↔️ Enhance basicity

  Electron-Withdrawing Groups ↔️ Reduce basicity
• What effect does steric hindrance have on amine basicity?

  Reduces basicity
• Aromatic amines are more basic than aliphatic amines due to conjugation with the aromatic ring.

  False
• How does conjugation with an aromatic ring affect the basicity of aromatic amines?

  Reduces basicity
• Electron-donating groups attached to the aromatic ring of an aromatic amine increase its basicity