Overview of Functional Groups in Organic Molecules

Introduction to Hydrocarbons and Functional Groups

• Hydrocarbons are important for combustion and fuel.
• Functional groups are added to hydrocarbons to create biologically interesting molecules.

Key Functional Groups

1. Hydroxyl Group (–OH)

• Definition: When –OH is attached to a carbon backbone, it forms an alcohol.
• Example: Ethanol (C2H5OH)
  • Properties:
    • Oxygen is electronegative, creating partial charges.
    • Polar and hydrophilic (dissolves in water).
    • Can form hydrogen bonds.

2. Sulfhydryl Group (–SH)

• Definition: Similar to hydroxyl but contains sulfur.
• Properties:
  • Less electronegative than oxygen, leading to less polarity.
  • Still polar but not as polar as hydroxyl groups.

3. Carbonyl Group (C=O)

• Definition: Present in sugars like fructose.
• Properties:
  • Oxygen is highly electronegative in double bond, leading to partial charges.
  • Polar, contributes to the overall polarity of the molecule.
• Structure:
  • Fructose has multiple hydroxyl groups and one carbonyl group.

4. Carboxyl Group (–COOH)

• Definition: Contains a carbonyl and a hydroxyl group.
• Properties:
  • Acidic because it can donate a hydrogen ion (proton).
  • Resonance allows electrons to be shared within the group.
• Example: Found in amino acids.

5. Amino Group (–NH2)

• Definition: Contains nitrogen.
• Properties:
  • Basic, can pick up a proton due to a lone pair of electrons.
• Example: Present in amino acids, contributes to their basic characteristics.

6. Methyl Group (–CH3)

• Definition: A hydrocarbon group with one carbon and three hydrogens.
• Properties:
  • Non-polar and hydrophobic, does not dissolve in water.

7. Phosphate Group (–PO4)

• Definition: Important in biological molecules (e.g., ATP, DNA backbone).
• Properties:
  • Acidic, can donate protons when protonated, contributing to acidity.

Summary

• Understanding these functional groups is crucial in studying biology and complex organic molecules.
• Recognize how different functional groups contribute to the properties and functions of biological molecules.