Organic Chemistry Exam Topics

Exam Format and Topics

• Number of Problems: 5
• Topics Covered:
  1. Proton NMR questions
  2. Naming with stereochemistry (E/Z nomenclature, functional groups)
  3. Completing reactions and reagents (epoxides, alcohols, Grignard reaction, ethers, carbocation rearrangements)
  4. Carbocation rearrangement mechanism
  5. Synthesis questions

Problem 1: Proton NMR Question

• Process: Deduce structure using molecular formula and proton NMR spectrum.
  • Degrees of Unsaturation: Calculate by comparing to the alkane formula (C_nH_2n+2).
  • Signals: Identify unique signals and their integration.
  • Chemical Shift: Use a table to note chemical shift, coupling, and integration.
  • Symmetry and Structure: Symmetry in molecule suggests few unique hydrogen positions.

Problem 2: Naming

• Focus: Naming organic compounds while considering E/Z stereochemistry.
  • Steps:
    • Identify highest priority functional group (Ketone takes priority over alcohol and alkene).
    • Numbering and naming substituents.
    • Incorporate stereochemistry at the end (R/S priority sequence).
  • Double Bonds: Use E/Z terminology for double bonds.

Problem 3: Completing the Reaction

• Part A: Oxidation of Alcohols

  • Reagent: PCC (or other oxidation reagents)
  • Outcome: Secondary alcohols to ketones; tertiary alcohol unchanged.

• Part B: Grignard Reaction and Protection

  • Steps:
    • Protect Alcohol: Convert to ether.
    • Create Grignard Reagent: Use Mg to prepare.
    • React with Carbonyl: Nucleophilic addition to form alcohol.
    • Deprotect: Convert ether back to alcohol.

• Part C: Carbocation Rearrangement

  • Use of hydride shift to stabilize carbocations.

Problem 4: Mechanism with Carbocations

• Pinnacle Rearrangement: Analyze given information to predict outcomes.
  • Key Concept: Carbocation stabilization next to oxygen.
  • Approach: Utilize known mechanisms and rearrangement principles.

Problem 5: Synthesis Question

• Goal: Synthesize target molecule from carbon pieces.
  • Strategy: Use retrosynthetic analysis to deconstruct target.
  • Key Reactions: Grignard reactions, forming and breaking carbon-carbon bonds.
  • Functional Group Transformations: Consider oxidation and reduction steps.

General Tips:

• Exam Strategy: Understand concepts over memorization.
• Tools: Visual aids such as resonance structures and stereochemistry models.
• Practice: Exposure to various problems enhances problem-solving skills.

Ensure thorough understanding of reaction mechanisms and molecular transformations for success in organic chemistry exams.