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Key Organic Chemistry Concepts for Exam

Sep 10, 2024

Organic Chemistry Exam Review

Key Topics Covered

  • Functional Groups
  • Lewis Structures
  • Hybridization
  • Sigma and Pi Bonds
  • Resonance Structures
  • Acids and Bases
  • Newman Projections
  • Boiling Points
  • Cherykov (likely typo intended as "Chirality" or similar) Formations

Glutathione Functional Groups

  • Glutathione is a tripeptide molecule with glutamic acid, cysteine, and glycine.
  • Functions as an antioxidant; contains two amide functional groups.
  • Contains a thiol group (RSH), which is crucial for antioxidant properties.
  • The oxidized form involves a disulfide bridge.
  • Functional group not present: Ketone

Drawing Lewis Structures

  • CH3CN: Carbon forms four bonds, hydrogen one; triple bond between carbon and nitrogen.
  • C2H2 (Acetylene): Triple bond between two carbons, each with a hydrogen.
  • C6H5CH2N2: Benzene (phenyl) ring with CH2 and N2 resembling nitrogen gas. Nitrogen has a positive formal charge.
  • CH3COCH3: Ketone structure with a double bond between carbon and oxygen.
  • CH3CO3H (Peroxy Acid): Carbonyl oxygen with two other oxygens.
  • CH3CO2 (Ester): Single carbon bonded to an oxygen and a double-bonded oxygen.
  • CH3(CH2)3CHO (Aldehyde): Aldehyde group at the end.
  • Amide Group: Carbon with a double-bonded oxygen and NH2.

Hybridization

  • Methane (CH4): sp3 hybridized.
  • Formaldehyde (CH2O): sp2 hybridized.
  • Hydrogen: Always s hybridized.
  • Hybridization Rules: Sum of exponents equals number of groups around the atom.
  • Examples: Methane (sp3), Ammonia (sp3), Water (sp3), Ethylene (sp2), Acetylene (sp).

Bond Strength

  • Ethane vs Ethylene: Sigma and pi bond energy comparison.
  • Sigma bonds are generally stronger than pi bonds.
  • Double bonds stronger than single bonds.

Resonance Structures

  • Major contributor has more stable structure (negative charge on more electronegative atom like nitrogen).
  • Resonance hybrid shows shared pi bonds and charge distribution.

Acidity

  • Compound B vs A: Higher acidity due to sulfur's larger atomic size stabilizing the negative charge better.
  • Atomic size impacts acidity more than electronegativity here.

Boiling Points

  • Straight-chain hydrocarbons have higher boiling points than branched ones.
  • Presence of hydrogen bonds increases boiling point.
  • More carbon atoms generally increase boiling point.

Newman Projections

  • 2-Methylbutane: Least stable conformation has methyl groups eclipsed.
  • Energy profile calculated for eclipsed configuration.

Chair Conformations

  • Conversion from chair to bond line structure involves positioning groups correctly based on direction (up or down).

These notes cover foundational concepts in organic chemistry that are critical for understanding molecular structure and behavior, particularly for exam preparation.

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