Organic Chemistry
Organic Chemistry on the OAT tests structure, nomenclature, functional groups, stereochemistry, reaction mechanisms, aromatic chemistry, carbonyl chemistry, and spectroscopy. The exam favors recognizing patterns and predicting products rather than memorizing long pathways.
Core rules
- Carbon hybridization explains geometry: sp³ tetrahedral, sp² trigonal planar, sp trigonal linear. A pi bond restricts rotation.
- Functional groups determine reactivity: alcohols, ethers, amines, aldehydes, ketones, carboxylic acids, esters, amides, and aromatic rings each have characteristic reactions.
- SN2 is one step with backside attack and inversion; SN1 is two steps through a carbocation and favors tertiary substrates. E2 is concerted and strongly favored by strong bulky bases.
- Markovnikov addition places H on the carbon with more hydrogens; anti-Markovnikov occurs with peroxides for HBr addition.
- Degree of unsaturation: DBE = (2C + 2 − H)/2 for neutral hydrocarbons. Each ring or pi bond counts as one DBE.
Worked example
For C₅H₈, DBE = (2 × 5 + 2 − 8)/2 = (12 − 8)/2 = 2. The formula therefore has two rings and/or pi bonds, such as a triple bond or two double bonds.
Traps
Do not confuse a nucleophile with a base; do not assign R/S without checking priority 4; do not assume all good nucleophiles are strong bases; do not ignore resonance stabilization; do not read IR as identifying every carbon environment.