Amines

• What is the fundamental structure of amines based on?

  Ammonia
• Amines are classified as primary, secondary, or tertiary
• What structural feature characterizes aromatic amines?

  Benzene ring
• Aromatic amines are used in the manufacture of dyes.
• What is the general formula of aliphatic amines?

  C_nH_{2n+3}N</latex>
• Primary aliphatic amines are prepared from halogenoalkanes using excess ammonia
• Steps in the nucleophilic substitution mechanism for preparing primary amines

  1️⃣ NH₃ attacks the halogenoalkane

  2️⃣ Formation of a positively charged intermediate

  3️⃣ Removal of H⁺ to form R-NH₂
• What type of reaction is used to prepare primary amines from nitriles?

  Reduction
• Amines are weak bases due to the lone pair of electrons on the nitrogen atom
• Primary aliphatic amines are stronger bases than ammonia.
• Match the type of amine with its relative basicity compared to ammonia:

  Primary aliphatic amines ↔️ Stronger

  Primary aromatic amines ↔️ Weaker
• Why are aromatic amines weaker bases than aliphatic amines?

  Lone pair delocalization
• A nucleophile is an electron pair donor.
• Steps in the nucleophilic substitution mechanism for amines with halogenoalkanes

  1️⃣ Lone pair on nitrogen attacks C

  2️⃣ Formation of a charged intermediate

  3️⃣ Loss of H⁺ to form R-NH₂
• What is the end product when a primary amine reacts with a halogenoalkane?

  Secondary amine
• Why are amines considered nucleophiles?

  They donate electron pairs
• Amines participate in nucleophilic substitution and addition-elimination reactions
• A nucleophile is an electron pair donor
• What is the general equation for the nucleophilic substitution reaction of ammonia with a halogenoalkane?

  RX + 2NH₃ → R-NH₂ + NH₄⁺X⁻
• Outline the mechanism for the nucleophilic substitution reaction of ammonia with a halogenoalkane.

  1️⃣ Lone pair of electrons on nitrogen in NH₃ attacks the δ+ carbon in the halogenoalkane

  2️⃣ Cl⁻ is released as a leaving group

  3️⃣ A proton is transferred to form R-NH₂ and H⁺Cl⁻
• 1°, 2°, and 3° amines react with halogenoalkanes by nucleophilic substitution
• What does the product formed from the reaction of an amine with a halogenoalkane depend on?

  The conditions used
• Excess halogenoalkane reacts with an amine to form a quaternary ammonium salt
• Match the use of quaternary ammonium salts with a specific product.

  Cationic surfactants ↔️ Household products

  Ionic region ↔️ Soluble in water

  Hydrocarbon region ↔️ Insoluble in water
• What is the general equation for the nucleophilic addition-elimination reaction of ammonia with an acyl chloride?

  R-C-Cl + NH₃ → RCONH₂ + HCl
• The nucleophilic addition-elimination reaction of ammonia with an acyl chloride produces a 1° amide
• Outline the mechanism for the nucleophilic addition-elimination reaction of an amine with an acyl chloride.

  1️⃣ Lone pair of electrons on nitrogen in the amine attacks the δ+ carbon in the acyl chloride

  2️⃣ Cl⁻ is released as a leaving group

  3️⃣ A proton is transferred to form R-C-NHR' and H⁺Cl⁻
• The reaction of ammonia with an acid anhydride produces a 1° amide and a carboxylic acid
• How are primary aliphatic amines prepared?

  Reaction of ammonia with halogenoalkanes
• Amines are weak bases
• The base strength of amines depends on the availability of the lone pair of electrons on the nitrogen atom