Organic Chemistry Final Exam Review

This study guide provides notes on a multiple-choice final exam review for the first semester of organic chemistry.

Functional Groups

• Aldehyde: Identified by -CHO.
• Ester: Contains RCOOR', with two oxygens connected to a carbon.
• Amine: Contains NH2 group.
• Ether: Oxygen connected to two R groups (ROR').
• Carboxylic Acid: COOH group.
• Alcohol: OH group.
• Amide: NH2 connected to a carbonyl group.

Nomenclature and Stability

• IUPAC Naming:
  • Longest chain determines the base name (octane, pentane, etc.).
  • Number chain for lowest substituent numbers.
  • Ethyl and methyl groups should be numbered for lowest position.
• Carbocation Stability:
  • Tertiary (3 carbons attached) > Secondary > Primary.
  • Allylic (one carbon away from a double bond) has resonance stability.

Hybridization

• SP3: 4 groups/lone pairs attached.
• SP2: 3 groups/lone pairs.
• SP: 2 groups/lone pairs.
• S: Single bond for hydrogen atoms.

Formal Charges and Lewis Structures

• Formal Charge = Valence Electrons - Bonds + Dots.
• Check for resonance structures to evaluate stability.

Resonance Structures

• Electrons can move in resonance structures; atoms cannot.
• Trans and cis isomers represent different 3D structures; not resonance.

Acidity and Basicity

• Lewis Base: Donates electron pairs.
• Lewis Acid: Accepts electron pairs.
• Strong acids have low pKa values.
• OH > NH in acidity due to electronegativity.

Reaction Mechanisms

• Hydroboration-Oxidation: Anti-Markovnikov; OH adds to less substituted carbon.
• Oxymercuration-Demercuration: Markovnikov addition; no rearrangement, OH adds to more substituted carbon.
• Radical Reactions: Br2 with light initiates radical halogenation at most stable carbon.

Stereochemistry

• R/S Configuration: Determined by priority of groups attached to chiral center.
• Syn/Anti Addition: Specifies addition direction in reaction.

Mesomers and Racemic Mixtures

• Meso Compounds: Achiral compounds with chiral centers and plane of symmetry.
• Racemic Mixtures: Equal mix of enantiomers; usually from reactions with carbocations.

Practice Problems

1. Identify functional groups not present in a molecule using structure and options.
2. Use IUPAC rules to name compounds based on chain length and substituent positions.
3. Determine the most stable carbocation in given structures.
4. Assign hybridization to atoms in given structures based on attached groups.
5. Calculate formal charges in Lewis structures to determine stability.
6. Distinguish between resonance and isomer structures.
7. Identify Lewis acids and bases in reactions.
8. Compare acid strengths using pKa values and molecular structure.
9. Predict major products of organic reactions based on reagents and conditions.
10. Use mechanisms to explain product formation in reactions.

These notes provide a concise review of key concepts in organic chemistry, focusing on functional groups, nomenclature, reaction mechanisms, stereochemistry, and acidity/basicity, essential for preparing for a final exam.