Reactions of amines

Page 1: Introduction to Amines

• Amines: Organic compounds derived from ammonia, characterized by the presence of nitrogen.

• Properties: Amines contain polar bonds, enabling primary and secondary amines to form hydrogen bonds with each other and with water, contributing to their solubility.

Page 2: Hydrogen Bonding in Amines

• Types of Amines:

  • Primary and Secondary Amines: Able to form hydrogen bonds with both water molecules and each other.

  • Tertiary Amines: Can only form hydrogen bonds with water, not with themselves.

• Strength of Bonds: Hydrogen bonds in amines are weaker than those in alcohols due to nitrogen's lower electronegativity compared to oxygen.

Page 3: Boiling Points of Amines

• Comparative Boiling Points:

  • Amines have higher boiling points than alkanes but lower than alcohols.

  • Primary Amines: Can form more hydrogen bonds, resulting in higher boiling points than secondary amines of similar mass.

  • Tertiary Amines: Do not form hydrogen bonds with each other, leading to lower boiling points compared to primary and secondary amines of the same mass.

Page 4: Solubility of Amines in Water

• Hydrogen Bonding: Amines with polar bonds can create hydrogen bonds with water.

• Solubility Considerations: Amines containing one to six carbon atoms, including tertiary amines, are generally soluble in water.

• Effect of Carbon Atoms: As the carbon chain in amines increases, the nonpolar characteristics of the hydrocarbon portion diminish hydrogen bonding effects, decreasing solubility.

Page 5: Solubility Visual

• Diagram: Illustrates interactions between primary, secondary, and tertiary amines with water through hydrogen bonding.

Page 6: Further Details on Solubility

• Amines with over Six Carbon Atoms:

  • Diminished impact of hydrogen bonding.

  • Increased nonpolar hydrocarbon chain reduces solubility in water.

Page 7: Learning Check 1

• Question: Identifies various compounds and asks which are soluble in water.

Page 8: Solution to Learning Check 1

• Answer Options: A and B are soluble in water; C (an alkane) is not, and D (an amine with over six carbons) is not soluble in water.

Page 9: Amines as Bases in Water

• Role as Bases: Amines exhibit behavior as Brønsted–Lowry bases.

• Mechanism: The lone pair on nitrogen accepts a proton from water, resulting in an ammonium ion and a hydroxide ion.

Page 10: Neutralization of Amines

• Formation of Amine Salts: Occurs when amines with odors (like fish) react with acids.

• Chemical Reaction: As amines react as Brønsted–Lowry bases, they form ammonium salts that eliminate unpleasant odors.

Page 11: Neutralization Reaction Process

• Acid and Amine Interaction:

  • Amine acts as a base; nitrogen's lone pair receives a proton from the acid to form an ammonium salt without the generation of water.

• Nomenclature: Named by combining the alkylammonium ion with the anion’s name.

Page 12: Examples of Neutralization

• Chemical Equations:

  • Methylamine + HCl → Methylammonium chloride

  • Dimethylamine + HCl → Dimethylammonium chloride

Page 13: Quaternary Ammonium Salts

• Definition: A nitrogen atom is bonded to four carbon groups, classifying it as a quaternary amine.

• Charge: The nitrogen carries a positive charge and is not bonded to any hydrogen atoms.

• Example: Choline, a quaternary ammonium ion found in glycerophospholipids.

Page 14: Properties of Ammonium Salts

• Characteristics:

  • Ionic nature results in strong attraction between the ammonium ion and anions (often chloride).

  • Generally solids at room temperature, odorless, and soluble in both water and biological fluids.

  • Often, amines are converted to ammonium salts for medicinal applications.

Page 15: Ammonium Salts in Medicines

• Active Ingredients: Examples include:

  • Ephedrine: A bronchodilator in Sudafed.

  • Diphenylhydramine: Found in Benadryl for skin irritation relief.

Page 16: Cocaine and Ammonium Salts

• Cocaine Hydrochloride: An ammonium salt that is often smuggled and used illegally.

• Free Base Form: Crack cocaine, a solid product absorbed rapidly when smoked, leading to stronger effects than hydrochloride form.

Page 17: Converting Cocaine Hydrochloride

• Conversion Process: Cocaine hydrochloride can be reverted back to its free amine or base form, known as crack cocaine, via treatment with a strong base.

Page 18: Learning Check 2

• Task: Draw the structural formula for the ammonium salt formed from trimethylamine and HCl.

Page 19: Solution to Learning Check 2

• Answer: Structural formula for the compound resulting from the reaction of trimethylamine and HCl.