Organic Chemistry

🏥 Organic Chemistry

Part 1 of 7 — Functional Groups & Nomenclature

Key functional groups: hydroxyl (-OH), carbonyl (C=O), carboxyl (-COOH), amino (-NH2), thiol (-SH).

Naming: find the longest carbon chain, number from the end nearest the first substituent.

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Key Insight: Degree of unsaturation (DoU) = (2C + 2 + N - H - X) / 2 — predicts rings and double bonds.

MCAT Tip: Functional group interconversions are heavily tested: alcohol to aldehyde to carboxylic acid.

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Stereochemistry

Part 2 of 7 — Stereochemistry

Chirality: a carbon with 4 different substituents is a chiral center (stereocenter).

R/S configuration: assign priorities by atomic number (Cahn-Ingold-Prelog rules).

Concept Check 🎯

Key Insight: Enantiomers: nonsuperimposable mirror images with identical physical properties but opposite optical rotation.

MCAT Tip: Diastereomers: stereoisomers that are NOT mirror images — different physical properties.

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Substitution & Elimination

Part 3 of 7 — Substitution & Elimination

SN1: two steps, carbocation intermediate, racemization, favored by 3-degree substrate and polar protic solvent.

SN2: one step, backside attack, inversion of configuration, favored by 1-degree substrate and strong nucleophile.

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Key Insight: E1: two steps, carbocation, Zaitsev product (more substituted alkene), competes with SN1.

MCAT Tip: E2: one step, anti-periplanar geometry required, strong base needed, Zaitsev product preferred.

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Carbonyl Chemistry

Part 4 of 7 — Carbonyl Chemistry

Aldehydes (RCHO) are more reactive than ketones (RCOR) due to less steric hindrance.

Nucleophilic addition: nucleophile attacks electrophilic carbonyl carbon.

Concept Check 🎯

Key Insight: Aldol condensation: alpha-carbon of one aldehyde attacks another to form beta-hydroxy carbonyl.

MCAT Tip: Hemiacetal/acetal formation: important for cyclic sugar chemistry on the MCAT.

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Carboxylic Acid Derivatives

Part 5 of 7 — Carboxylic Acid Derivatives

Order of reactivity: acid halide > anhydride > ester > amide (most to least reactive).

Nucleophilic acyl substitution: the leaving group departs as the nucleophile attacks.

Concept Check 🎯

Key Insight: Esters undergo hydrolysis (saponification with base) — critical for lipid metabolism.

MCAT Tip: Amide bond formation: condensation of carboxylic acid + amine — this is the peptide bond.

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Spectroscopy & Structure

Part 6 of 7 — Spectroscopy & Structure

IR spectroscopy: O-H broad ~3300, N-H sharp ~3300, C=O sharp ~1700, C-H ~2900 cm-1.

1H NMR: chemical shift indicates electronic environment; splitting follows n+1 rule.

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Key Insight: Mass spectrometry: molecular ion peak gives molecular weight; fragmentation reveals structure.

MCAT Tip: UV-Vis: conjugated systems absorb longer wavelengths — more conjugation = lower energy transition.

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Review & MCAT Practice

Part 7 of 7 — Review & MCAT Practice

IR spectroscopy: O-H broad ~3300, N-H sharp ~3300, C=O sharp ~1700, C-H ~2900 cm-1.

1H NMR: chemical shift indicates electronic environment; splitting follows n+1 rule.

Concept Check 🎯

Key Insight: Mass spectrometry: molecular ion peak gives molecular weight; fragmentation reveals structure.

MCAT Tip: UV-Vis: conjugated systems absorb longer wavelengths — more conjugation = lower energy transition.

Concept Check 🎯

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