18.1.2 Basicity of Amines

• What are amines derived from?

  Ammonia
• Amines exhibit basic properties due to the presence of a lone pair of electrons on the nitrogen atom
• The basicity of an amine is influenced by the availability of the lone pair
• Electron-donating alkyl groups increase the basicity of amines by increasing electron density on the nitrogen
• What stabilizes the conjugate acid of an amine, thereby increasing its basicity?

  Electron-donating groups
• Order the basicity of primary, secondary, and tertiary amines from most to least basic

  1️⃣ Secondary

  2️⃣ Primary

  3️⃣ Tertiary
• Match the type of amine with its relative basicity:

  Primary ↔️ Moderately Basic

  Secondary ↔️ More Basic

  Tertiary ↔️ Less Basic
• Secondary amines are generally more basic than primary amines due to electron-donating alkyl groups
• Which type of amine is most affected by steric hindrance?

  Tertiary
• Match the type of amine with its relative basicity compared to aliphatic amines:

  Aromatic amines ↔️ Less Basic

  Aliphatic amines ↔️ More Basic
• Why are aromatic amines less basic than aliphatic amines?

  Delocalization of lone pair
• The delocalization of the lone pair in aromatic amines makes it less available for protonation
• The delocalization of the lone pair in aromatic amines reduces their basicity
• What effect do electron-donating groups have on amine basicity?

  Increase
• Alkyl groups are examples of electron-donating groups that increase amine basicity
• Electron-withdrawing groups such as halogens decrease electron density on the nitrogen, making the lone pair less available for protonation
• Electron-donating groups increase basicity, while electron-withdrawing groups decrease
• What is a common example of an electron-donating group?

  Alkyl groups
• Halogens are electron-withdrawing groups that reduce electron density on nitrogen.
• Electron-donating groups increase electron density on nitrogen
• Which type of electronic effect increases the basicity of an amine?

  Electron-donating effect
• Alkyl groups are electron-donating groups that enhance amine basicity.
• Amines are organic compounds derived from ammonia
• What is the key property of amines that makes them basic?

  Lone pair of electrons
• Order the basicity of different types of amines from most basic to least basic.

  1️⃣ Secondary (R_{2}NH</latex>)

  2️⃣ Primary ($RNH_{2}$)

  3️⃣ Tertiary ($R_{3}N$)
• Which factor stabilizes the conjugate acid of an amine, increasing its basicity?

  Electron density
• Electron-donating groups increase the availability of the lone pair in amines.
• Alkyl groups increase electron density on the nitrogen atom, making the lone pair more available for protonation
• Why are aromatic amines less basic than aliphatic amines?

  Lone pair delocalization
• Bulky alkyl groups around the nitrogen atom can hinder the approach of protons, reducing basicity.
• Match the amine type with its basicity:

  Aliphatic ↔️ More Basic

  Aromatic ↔️ Less Basic
• Why is the lone pair in aromatic amines less available for protonation?

  Delocalization into the ring
• The structure of an aliphatic amine is $R - NH_{2}$
• Electron-donating groups like alkyl groups increase the availability of the lone pair for protonation
• Which group is an example of an electron-withdrawing group attached to nitrogen in an amine?

  Halogen
• Steric hindrance in amines reduces the accessibility of the lone pair for protonation.
• Order the protonation accessibility of different types of amines from highest to lowest.

  1️⃣ Primary ($RNH_{2}$)

  2️⃣ Secondary ($R_{2}NH$)

  3️⃣ Tertiary ($R_{3}N$)
• Which type of amine has low steric hindrance and allows easier protonation?

  Primary amine
• Secondary amines have higher basicity compared to tertiary amines due to less steric hindrance.
• Secondary amines, with two alkyl groups, offer the highest basicity