Organic Chemistry 2 Exam 1 Review - Spring 2022

Introduction

• Lecture re-recorded and uploaded on Valentine's Day.
• Covers the first exam's key concepts and problems.

Nomenclature Section

Epoxide Naming

• Epoxide as a Parent Chain:

  • Longest carbon chain starting with alcohol.
  • Numbering: 1-4.
  • Naming: 1-butenol, substituents: 4-bromo, 2,3-epoxy.
  • Stereochemistry:
    • Use R/S or cis.
    • 2R, 3S possible.

• Epoxide as a Substituent:

  • Name as oxirane when epoxide is parent chain.
  • Substituents: 2-bromo-methyl, 3-hydroxymethyl.
  • Stereochemistry: cis or 2R, 3S.

Ether Naming

• Ethers have lower priority than alkenes.
• Longest chain with most alkenes is preferred.
• Numbering based on substituents proximity.
  • E.g., 3-ethoxy, 4-butyloxy, 1,6-heptadiene.

Ranking Reactivity & Stability

Carbocation Stability

• Order: Tertiary > Secondary (resonance) > Primary.

Reactivity with Sodium Iodide in Acetone

• Order: Secondary allylic > Secondary > Vinyl (SP2, no reaction).

Reactivity with Grignard Reagent

• Note: Grignard reacts with epoxides, not ethers.
• Order: Least substituted epoxide more reactive.

Resonance Structure Stability

• Stable: Negative charge on most electronegative (Oxygen > Nitrogen > Carbon).
• Hybridization: Lowest energy state, typically SP2.

Diels-Alder Reaction

• Reactivity Criteria:
  • Diene: More electron-donating groups preferred.
  • Dienophile: More electron-withdrawing groups preferred.

Spectroscopy

NMR Signals

• Multiplicity:
  • H-A: 21 signals from interacting hydrogens.
  • H-B: 2 signals.
  • H-C: 4 signals.

Reactions

• Sequential Reactions:
  • Example: Markovnikov addition of OH-Br, formation of epoxide, and subsequent transformations.

Synthesis

• Using Reagents:
  • Convert alcohols, alkenes, and alkynes with specific reagents.
  • Example processes: making a Grignard reagent, oxidation to ketone/alcohol, PCC for aldehyde formation.

Spectroscopy Problem

• Analysis:
  • Benzene with C9H12O2 indicating certain functional groups.
  • Techniques: IR for OH stretch, NMR for unique hydrogen environments.
  • Conclusion: Build structure using given data (e.g., para-substituted benzene).

Conclusion

• Good luck on the exam.
• Acknowledge the delay in video delivery.