Organic Chemistry Final Exam Comprehensive Review

Octet Rule

The principle that most atoms will share electrons (covalent bonding) or transfer electrons (ionic bonding) to obtain a total of $8$ electrons in its valence shell.

Formal Charge

A value assigned to an atom calculated as: $\text{Normal Valence } e^- - (1/2 \text{ bonding electrons} + \text{nonbonding electrons})$.

Sigma Overlap

The end-to-end overlap of any $2$ orbitals; all single bonds are characterized as sigma bonds.

Pi Overlap

The sideways overlap of $p$ orbitals, which are only present in multiple bonds.

s-character

The percentage of s-orbital contribution in hybrid orbitals, where greater s-character results in lower energy and greater stability of a base (sp > sp^2 > sp^3).

Steric Strain

Repulsion between the electron clouds of atoms.

Torsional Strain

Repulsion between bonding electrons.

Allylic

A carbon atom that is adjacent to an alkene.

Benzylic

A carbon atom that is adjacent to a benzene ring.

Constitutional Isomers

Compounds with the same molecular formula but different connectivity; also referred to as structural isomers.

Enantiomers

Chiral compounds that have nonsuperimposable (non-identical) mirror images.

Diastereomers

Nonsuperimposable (non-identical) non-mirror images, such as cis/trans isomers.

Racemic Mixture

A $50/50$ mixture of enantiomers that is optically inactive.

Meso Compounds

Compounds that are achiral but contain chiral centers.

Chiral Centers

Tetrahedral atoms ($sp^3$ hybridized) that have four different substituents.

Br%nsted-Lowry Acid

A chemical species that acts as an $H^+$ donor.

Lewis Base

A chemical species that acts as an $e^-$ donor.

Induction

The stabilization of a base by electron-withdrawing groups (electronegative atoms) located near the basic atom, which lowers electron energy.

Walden Inversion

The inversion of configuration that occurs during a concerted $S_N2$ reaction.

Zaitsev Product

The major product in elimination reactions which corresponds to the more substituted alkene.

Hofmann Product

The less substituted alkene major product in elimination reactions, typically favored when using a strong, bulky base.

s-cis Conformation

The specific orientation where a diene must be placed to participate in a Diels-Alder reaction.

Endo Rule

The stereoselective preference in Diels-Alder reactions where electron-withdrawing groups prefer the endo positions.

Sigma Complex

The

Reagent: Sodium Borohydride (NaBH₄)

A reducing agent commonly used to reduce ketones and aldehydes into alcohols.

Reagent: Lithium Aluminum Hydride (LiAlH₄)

A strong reducing agent that can reduce esters, carboxylic acids, and amides to alcohols.

Reagent: Potassium Permanganate (KMnO₄)

An oxidizing agent that can oxidize alcohols to ketones or carboxylic acids, depending on conditions.

Reagent: Hydrochloric Acid (HCl)

A strong acid used in various reactions, including the conversion of alcohols to alkyl chlorides.

Reagent: Sulfuric Acid (H₂SO₄)

A strong acid often used as a dehydrating agent in the conversion of alcohols to alkenes.

Reaction: Diels-Alder Reaction

A cycloaddition reaction between a diene and a dienophile to form a cyclohexene derivative.

Reaction: Grignard Reaction

A reaction between a Grignard reagent and a carbonyl compound to form an alcohol.

Reaction: Esterification

A reaction where a carboxylic acid reacts with an alcohol in the presence of an acid catalyst to form an ester.

Reaction: Aldol Condensation

A reaction between aldehydes or ketones to form a β-hydroxy carbonyl compound, followed by dehydration to yield an α,β-unsaturated carbonyl.

Reaction: Free Radical Halogenation

A reaction where alkanes react with halogens under light or heat to form alkyl halides.

Reagent: Bromine Water (Br₂)

Used as a test for unsaturation; reacts with alkenes and alkynes, causing the solution to lose its color.

Reagent: Zinc (Zn)

A reducing agent used in various reactions, including the reduction of nitro compounds to amines.

Reaction: SN1 Reaction

A substitution reaction characterized by a two-step mechanism where the rate-determining step involves the formation of a carbocation.

Reaction: SN2 Reaction

A substitution reaction characterized by a one-step mechanism where the nucleophile attacks the substrate and displaces the leaving group simultaneously.

Reagent: Sodium hydroxide (NaOH)

A strong base often used in nucleophilic substitution and elimination reactions.

Reaction: Oxidative Cleavage of Alkenes

A reaction where alkenes are cleaved using oxidative agents like ozonolysis to form carbonyl compounds.

Reagent: Acetic Acid (CH₃COOH)

A weak acid used in various reactions, including esterification and as a solvent.

Reaction: Cannizzaro Reaction

A chemical reaction where aldehydes without alpha-hydrogens undergo disproportionation in the presence of a strong base to form alcohols and carboxylic acids.

Reagent: Acetyl chloride (CH₃COCl)

Used as an acylating agent in the formation of esters and amides.

Reaction: Ethanol + Acetic Anhydride

Reacting ethanol with acetic anhydride produces ethyl acetate (an ester) and acetic acid.

Reaction: Benzene + Chlorine (in presence of FeCl₃)

Benzene reacts with chlorine in the presence of iron(III) chloride to produce chlorobenzene via electrophilic aromatic substitution.

Reaction: 1-Hexene + H₂ (in presence of Pd)

1-hexene reacts with hydrogen in the presence of palladium to produce hexane through hydrogenation.

Reaction: Cyclohexene + KMnO₄

Cyclohexene reacts with potassium permanganate to produce glycol (1,2-cyclohexanediol) through syn-dihydroxylation.

Reaction: 2-Butanol + H₂SO₄

2-butanol reacts with sulfuric acid to produce butene (alkene) and water through dehydration.

Reaction: Propanal + Sodium Borohydride

Propanal reacts with sodium borohydride to produce propanol (an alcohol) through reduction.

Reaction: Acetophenone + 2,4-Dinitrophenylhydrazine

Acetophenone reacts with 2,4-dinitrophenylhydrazine to produce a hydrazone through condensation.

Reaction: Acetic Acid + Sodium Bicarbonate

Acetic acid reacts with sodium bicarbonate to produce sodium acetate, water, and carbon dioxide (gas).

Reaction: Octane + Oxygen

Octane reacts with oxygen in combustion to produce carbon dioxide and water.

Reaction: Ethyne + H₂ (in presence of Ni)

Ethyne (acetylene) reacts with hydrogen in the presence of nickel to form ethane through hydrogenation.