Organic Chemistry Comprehensive Review

A vocabulary-style comprehensive review of organic chemistry principles including physical properties, reaction types, thermodynamics, kinetics, the ARIO framework, and electronic effects.

Van der Waals (London Dispersion) Forces

Temporary, transient dipoles induced by fluctuating electron clouds that are present in all molecules and scale with surface area, molecular weight, and polarizability.

Dipole-Dipole Interactions

Permanent electrostatic attractions between the net positive ends and net negative ends of polar molecules containing asymmetric heteroatom bonds such as $C-O$, $C-Cl$, or $C=O$.

Hydrogen Bonding (H-Bonding)

A specialized subset of dipole-dipole interactions occurring when a hydrogen atom covalently bonded to a strongly electronegative atom ($N$, $O$, or $F$) is attracted to a lone pair on an adjacent $N$, $O$, or $F$ atom.

Ionic / Electrostatic Interactions

Ultra-strong coulombic attractions holding full, permanent formal charges together, such as in carboxylate salts ($RCOO^- Na^+$) or ammonium salts ($RNH_3^+ Cl^-$).

H-Bond Donor (HBD)

A structural fragment containing a hydrogen attached directly to $N$, $O$, or $F$, such as the $-OH$ of an alcohol or $-NH_2$ of an amine.

H-Bond Acceptor (HBA)

An electronegative atom ($N$, $O$, or $F$) possessing active lone pairs capable of receiving an electropositive hydrogen atom.

Boiling Point (BP) Trend

Increases directly with stronger IMFs and larger surface area, but decreases with branching as linear molecules become compact spheres.

Melting Point (MP) Trend

Increases with stronger IMFs and highly rigid, symmetric crystal lattice packing; often increases with symmetry in highly branched molecules like neopentane.

Aqueous Solubility Rule

Governed by "Like Dissolves Like" where hydrophilic groups enhance solubility; a standard rule is that $1$ polar group can solubilize about $4-5$ carbons.

Addition Reaction

A reaction where components are added across a multiple bond, breaking one weak $\pi$ bond to form two new strong $\sigma$ bonds.

Elimination Reaction

The reverse of an addition where two strong $\sigma$ bonds are severed to form a new weak $\pi$ bond, ejecting a small neutral fragment like water.

Substitution Reaction

A process where an atom or functional group is replaced by an incoming group, involving the breaking of one $\sigma$ bond and the formation of one new $\sigma$ bond at the target carbon.

Rearrangement Reaction

A skeletal migration where elements shift positions within the structure to yield a constitutional isomer, often involving hydride or alkyl group migrations.

Nucleophiles ($Nu^-$)

Electron-rich chemical units seeking positive centers that possess lone pairs, negative charges, or active $\pi$ systems.

Electrophiles ($E^+$)

Electron-deficient chemical units seeking electron density that contain full or partial positive charges or open valencies.

Enthalpy change ($\Delta H^\circ$)

Approximated by the calculation: $\Delta H^\circ = \sum BDE\text{(bonds broken, reactants)} - \sum BDE\text{(bonds formed, products)}$.

Gibbs Free Energy ($\Delta G^\circ$)

The energy dictating equilibrium spontaneity, calculated as $\Delta G^\circ = \Delta H^\circ - T\Delta S^\circ$ or $\Delta G^\circ = -RT \ln(K_{eq})$.

Transition States

Unstable chemical boundaries represented as peaks (local maxima) on an energy profile where bonds are partially forming or breaking.

Reaction Intermediates

Fully formed chemical structures, such as carbocations, represented by valleys (local minima) on an energy profile.

Activation Energy ($E_a$)

The height of the hill from reactant to peak which governs kinetics; a taller hill indicates a slower reaction and a shorter hill indicates a faster reaction.

Catalysts / Enzymes

Substances that accelerate reaction metrics exclusively by lowering the activation energy ($E_a$) without affecting $\Delta G^\circ$, $\Delta H^\circ$, or $K_{eq}$.

ARIO Framework

A priority hierarchy (Atom, Resonance, Induction, Orbital) used to evaluate the stability of a conjugate base ($A^-$) to determine the strength of its parent acid.

Atom (ARIO - Row Trend)

The rule that electronegativity dominates charge stability across a row ($C < N < O < F$), making $HF$ more acidic than $H_2O$.

Atom (ARIO - Column Trend)

The rule that atomic size dominates charge stability down a column ($F < Cl < Br < I$), making $HI$ more acidic than $HF$.

Resonance (ARIO)

The stabilization of a conjugate base through the delocalization of a negative charge across multiple atoms via conjugated $\pi$ systems.

Induction (ARIO)

The distribution of a conjugate base charge through the $\sigma$ framework caused by nearby electron-withdrawing atoms, intensifying with electronegativity, proximity, and quantity.

Orbital (ARIO)

The principle that stability follows $sp > sp^2 > sp^3$ hybridization because $sp$ orbitals have $50\%$ s-character, holding electrons closest to the stabilizing nucleus.

Hyperconjugation

Weak stabilizing orbital overlap between a filled neighboring $C-H$ or $C-C$ $\sigma$-bond and an adjacent vacant p-orbital, establishing the stability cascade: $3^\circ > 2^\circ > 1^\circ > \text{methyl}$.

Steric Effects

Van der Waals repulsive strains arising when atoms are physically forced into close geometric quarters, which can alter reaction velocity or regioselectivity.