Organic Chemistry Lecture Notes

Introduction to Organic Chemistry

• Focuses on organic compounds containing carbon atoms.
• Carbon typically forms four bonds.

Bond Formation Preferences

• Hydrogen (H): 1 bond
• Beryllium (Be): 2 bonds
• Boron (B): 3 bonds
• Carbon (C): 4 bonds
• Nitrogen (N): 3 bonds
• Oxygen (O): 2 bonds
• Halogens (F, Cl, Br, I): Usually 1 bond
  • Can form more in some cases.

Drawing Lewis Structures

• Understanding bond preferences aids in drawing Lewis structures.
• Example: Water (H2O)
  • Oxygen forms 2 bonds, hydrogen forms 1.
  • Add lone pairs to complete octet.

Types of Covalent Bonds

• Hydrogen Bond: Special type of covalent bond.
  • Occurs when H is bonded to N, O, or F.
• Polar Covalent Bond: Unequal sharing of electrons.
  • Example: Carbon-Fluorine bond.
• Nonpolar Covalent Bond: Equal sharing of electrons.
  • Example: Carbon-Hydrogen bond.

Ionic Bonds

• Involves transfer of electrons.
• Example: Sodium chloride (NaCl)
  • Sodium gives up an electron to become Na+, chlorine accepts to become Cl-.
• Result in electrostatic attraction between ions.

Alkanes and Alkenes

• Alkanes: Saturated hydrocarbons (CnH2n+2)
  • Examples: Methane (CH4), Ethane (C2H6), Propane (C3H8), etc.
• Alkenes: Unsaturated, contain at least one double bond.
  • Example: Ethene (C2H4).

Bond Lengths and Strengths

• Bond Length: Single > Double > Triple.
• Bond Strength: Triple > Double > Single.

Sigma and Pi Bonds

• Single bonds: 1 sigma bond.
• Double bonds: 1 sigma + 1 pi bond.
• Triple bonds: 1 sigma + 2 pi bonds.
• Sigma bonds are stronger than pi bonds.

Bond Order

• Single bond: Bond order 1.
• Double bond: Bond order 2.
• Triple bond: Bond order 3.

Hybridization

• Determined by the number of atoms and lone pairs around a carbon atom.
  • sp3: 4 groups
  • sp2: 3 groups
  • sp: 2 groups

Calculating Formal Charge

• Formula: Valence electrons - (Bonds + Dots)
• Example calculations provided for carbon, sulfur, and nitrogen.

Functional Groups and Lewis Structures

• Alcohol (OH): Ethanol (C2H5OH)
• Aldehyde (CHO): Ethanal
• Ketone (RCOR'): Propanone
• Ester (RCOOR'): Methyl Ethanoate
• Carboxylic Acid (COOH): Pentanoic acid

Expanding Structural Formulas

• Convert condensed formulas to full structures.
• Recognizing positions of CH3, CH2, and other groups in the structure.

Miscellaneous

• Radical: Molecule with an unpaired electron.
• Cations and Anions: Positive and negative ions respectively.
• Explanation of complex organic structures and functional groups.