Lecture Notes: Functional Groups in Organic Chemistry

Overview

• Discussion on functional groups from the Smith textbook, Chapter 3, Part 2.
• Review of naturally occurring and synthetic molecules with biological activity.

Key Molecules Discussed

• Dopamine: Neurotransmitter.
• Xylitol: Artificial sweetener.
• Morphine & Codeine: Naturally occurring opioid and its derivative.
• Heroin: Morphine derivative.
• Propofol: Anesthetic, hydrophobic, emulsified for administration.
• Aspirin, Acetaminophen, Benzocaine: Common pain relievers.
• DEET: Insect repellent.
• Ibuprofen: Painkiller, often confused with Tylenol.
• Prozac, Methadone, Vanillin, Penicillin: Various pharmaceuticals.
• Testosterone & Estrogen: Hormones responsible for secondary sexual characteristics.
• Ethinyl Estradiol: Component of birth control, mimics pregnancy.
• Aspartame: Artificial sweetener.

Functional Groups Overview

• Alcohols: Includes phenol (a special kind of alcohol).
• Amines: Primary, secondary, tertiary (based on R groups on nitrogen).
• Ethers: ROR structure.
• Alkenes: Carbon-carbon double bond.
• Esters and Amides: Carbonyl containing, derived from carboxylic acids.
• Carboxylic Acids: R-COOH structure.
• Aromatic Hydrocarbons: Contains benzene rings.
• Thiols and Sulfides: Contain sulfur, associated with strong odors.

Interactions and Properties

• Van der Waals Interactions: Momentary dipoles, weak forces.
• Dipole-Dipole Interactions: Stronger due to permanent dipoles.
• Hydrogen Bonding: Strong interactions, significantly affect boiling points.
• Ionic Bonds: Strong electrostatic attractions.

Physical Properties

• Boiling Points: Influenced by molecular weight and type of intermolecular forces.
  • Larger molecules typically have higher boiling points due to increased van der Waals forces.
  • Linear molecules generally have higher boiling points than spherical ones.
• Melting Points: Spherical molecules pack better in crystalline lattices, often more difficult to melt.

Examples and Comparisons

• Pentane vs Neopentane: Demonstrated effects of molecular shape on boiling points.
• Comparison of Alcohols, Ketones, and Alkanes: Highlighted differences in boiling points due to hydrogen bonding and dipole interactions.
• Carboxylic Acids: Form dimers, leading to higher boiling points.

Conclusion

• Understanding functional groups and intermolecular forces is crucial for predicting the physical properties of organic molecules.
• Recognizing the differences between molecular structures helps in anticipating their behavior in biological and chemical contexts.