⬡Organic Chemistry

Why molecules take the shape they do: Lewis structures, resonance, hybridization, and the functional groups the rest of the course is built from.

Lewis Structures and Formal Charge · Resonance Structures and Delocalization · Hybridization: sp3, sp2, and sp · VSEPR and Molecular Geometry · +2 more

The one skill that predicts almost every reaction to come: finding the acid, finding the base, and reading pKa to see which way it goes.

Bronsted-Lowry Acids and Bases · Lewis Acids and Bases · pKa and Predicting the Position of Equilibrium · Factors That Control Acidity · +1 more

Molecules are never frozen: bonds spin, rings pucker, and a chair flip trades every axial substituent for an equatorial one.

Nomenclature of Alkanes · Degrees of Unsaturation · Newman Projections and Rotation About a Single Bond · Conformations of Butane and Gauche Strain · +4 more

The three-dimensional shape of a molecule, not just its bonds: chirality, mirror images, and the rare case where both collapse into one.

Chirality and Stereocenters · Assigning R and S Configuration · Enantiomers and Optical Activity · Diastereomers · +4 more

The handful of moves that run every mechanism in the course: what a curved arrow really shows, and why some products win on speed while others win on stability.

Curved Arrows: What They Actually Show · Nucleophiles and Electrophiles · Thermodynamics vs Kinetics of a Reaction · Reaction Coordinate Diagrams and Transition States · +1 more

One stereocenter, two fates: SN2 inverts it like an umbrella catching the wind, SN1 flattens it into a carbocation and erases it entirely.

The SN2 Mechanism and Backside Attack · The SN1 Mechanism and Carbocation Formation · Stereochemistry of SN2: Inversion of Configuration · Stereochemistry of SN1: Racemization · +4 more

The same alkyl halides from the last unit, pushed a different way: a base rips off a proton, a pi bond forms, and the leaving group leaves.

The E2 Mechanism and Anti-Periplanar Geometry · The E1 Mechanism and Carbocation Intermediates · Zaitsev's Rule and the More Substituted Alkene · Hofmann Product with Bulky Bases · +1 more

One pi bond, a dozen different ways to break it: Markovnikov and anti-Markovnikov addition, bromonium ions, epoxides, and a double bond cut clean in two.

Alkene Nomenclature and E/Z Configuration · Alkene Stability and Heat of Hydrogenation · Addition of HX and Markovnikov's Rule · Carbocation Rearrangements During Electrophilic Addition · +8 more

The straight, sp-hybridized cousin of the alkene: a proton acidic enough to remove, and a triple bond that can absorb two full additions.

Alkyne Structure and Nomenclature · Acidity of the Terminal Alkyne · Addition of HX and X2 to Alkynes · Hydration of Alkynes and Tautomerization · +2 more

Bonds that split one electron to each atom instead of two to one, and the chain reactions that unpaired electron sets off.

Radical Initiation, Propagation, and Termination · Halogenation of Alkanes by a Radical Chain · Selectivity in Radical Halogenation · Allylic Bromination · +2 more

The hydroxyl group playing both roles at once, oxygen bridging two carbons, and the strained three-membered ring that answers to acid and base differently.

Nomenclature and Properties of Alcohols · Alcohols as Nucleophiles and as Electrophiles · Oxidation of Alcohols to Aldehydes, Ketones, and Acids · Williamson Ether Synthesis · +3 more

Turning a carbon-halogen bond into a carbon-metal bond flips carbon from electrophile to nucleophile, and hands a chemist a new carbon-carbon bond.

Making a Grignard Reagent · Grignard Addition to Carbonyl Compounds · Organolithium Reagents · Limitations of Organometallic Reagents with Protic Groups

How chemists know what they made: a fragmented molecular ion, a functional group's fingerprint, and a proton's neighbors counted from its own peak pattern.

Mass Spectrometry and the Molecular Ion · Fragmentation Patterns in Mass Spectrometry · IR Spectroscopy and Characteristic Absorptions · 1H NMR Chemical Shift · +5 more

Electrons spread across more than one bond at once, and two pi systems swinging together to build two new bonds in a single concerted step.

Conjugation and Overlapping p Orbitals · Allylic Cations and Extended Resonance · 1,2- vs 1,4-Addition to a Diene · Kinetic vs Thermodynamic Control in Diene Addition · +3 more

Why one particular ring of six carbons refuses to behave like an ordinary alkene, and the electron-counting rule that predicts which rings share its stability.

The Structure of Benzene · Criteria for Aromaticity · Huckel's Rule and the 4n+2 Count · Antiaromatic and Nonaromatic Systems · +1 more

Benzene keeps its aromaticity by swapping a hydrogen instead of adding across a double bond, and every substituent decides where the next one lands.

The General Mechanism of Electrophilic Aromatic Substitution · Halogenation of Benzene · Nitration and Sulfonation · Friedel-Crafts Alkylation · +4 more

Two escape routes off an aromatic ring that never touch a carbocation: a stabilized addition intermediate, and a strained triple bond hiding inside the ring.

The Addition-Elimination Mechanism of Nucleophilic Aromatic Substitution · The Benzyne Mechanism · Diazonium Salts and Their Reactions

The carbonyl as the course's key electrophile: a nucleophile drops in from above, and the tetrahedral intermediate it forms goes six different directions.

Nomenclature and Relative Reactivity of Carbonyls · Nucleophilic Addition to the Carbonyl · Hydration and Hemiacetal Formation · Acetal Formation as a Protecting Group · +3 more

A carbonyl with a leaving group attached: the same tetrahedral intermediate as a ketone, but one that collapses back down and kicks the leaving group out.

Nomenclature and Acidity of Carboxylic Acids · Relative Reactivity of Acyl Derivatives · Nucleophilic Acyl Substitution Mechanism · Fischer Esterification · +4 more

The carbon next to a carbonyl leads a double life: acidic enough to deprotonate, and nucleophilic enough to build a whole new carbon-carbon bond.

Keto-Enol Tautomerism · Enolate Formation and Alpha-Carbon Acidity · Alpha-Halogenation of Ketones · The Aldol Addition and Condensation · +4 more

Nitrogen's lone pair makes it the course's most versatile base and nucleophile at once, from grabbing a stray proton to building a diazonium salt.

Amine Structure and Basicity · Amine Nomenclature and Nucleophilicity · Synthesis of Amines by Reductive Amination · Synthesis of Amines by the Gabriel Synthesis · +2 more

Every earlier tool in one molecule: a Fischer projection's stereocenters, a hemiacetal closing into a ring, and a full acetal linking two rings together.

Fischer Projections of Monosaccharides · D and L Sugars · Cyclic Hemiacetal Formation and Anomers · Mutarotation · +2 more

A molecule with both a positive and a negative charge at once, linked to its neighbors by the same amide bond from the carboxylic acid unit.

Amino Acid Structure and the Zwitterion · Isoelectric Point and Electrophoresis · Peptide Bond Formation · Primary Through Quaternary Protein Structure · +1 more

Fatty acids that pack together or refuse to, a triester that turns into soap, and one fused ring skeleton behind every steroid in the body.

Fatty Acids and Saturation · Triglycerides and Saponification · Phospholipids and the Cell Membrane · Steroids and the Terpene Skeleton

Every reaction from the whole course, run in reverse: a target molecule breaking apart, branch by branch, back to the simple pieces it could be built from.

Thinking Backward: The Retrosynthetic Arrow · Choosing a Disconnection · Functional Group Interconversion in a Synthesis Plan · Protecting Groups in a Multi-Step Synthesis · +1 more