Organic Reactions and Preparations: Introduction to Organic Synthesis & Types of Reactions

Comprehensive vocabulary flashcards covering the fundamentals of organic synthesis, historical milestones, bonding principles, electronegativity trends, hybridization, resonance, and general classes of organic reaction mechanisms.

Synthesis (Etymology)

Derived from the Greek term meaning "put together".

Organic Synthesis

The set of methods and strategies chemists use to construct organic molecules from simpler starting materials.

Friedrich Wöhler (1828)

The chemist who reported the synthesis of urea in $1828$, an early milestone in organic synthesis.

Hermann Kolbe (1845)

The chemist who coined the term "synthesis" and synthesized acetic acid in $1845$.

Emil Fischer (1890)

The chemist who achieved the synthesis of glucose in $1890$, celebrated as one of the most remarkable syntheses of the 19th century.

Tetravalent

An atom that possesses $4$ valence electrons, needs $4$ electrons to complete its valence shell, and forms $4$ covalent bonds, such as carbon ($\text{C}$).

Divalent

An atom that possesses $6$ valence electrons, requires $2$ electrons to complete its outer shell, and forms $2$ bonds, such as oxygen ($\text{O}$).

Electronegativity

The power of an atom in a molecule to attract electrons to itself.

Polarized Bond

A covalent bond formed between atoms with an electronegativity difference, producing partial positive ($\delta+$) and partial negative ($\delta-$) charges.

Hybridization Effect on Electronegativity

The increase in orbital electronegativity corresponding to increasing percent $s$ character ($sp^3d^2 < sp^3d < sp^3 < sp^2 < sp$), which follows the order $\text{C}\equiv\text{CH} > \text{CH}=\text{CH}_2 > \text{CH}_3$.

Resonance (Mesomerism)

The use of two or more Lewis structures differing only in the placement of $\pi$ or nonbonding electrons to describe the bonding in a molecule.

Delocalization

The spreading of electrons over a larger part of a molecule, bringing them closer to more nuclei and stabilizing the resonance hybrid.

Ionic (Polar) Reactions

Organic reactions in which bond-forming and bond-breaking processes are associated with the movement of an electron pair.

Radical Reactions

Organic reactions in which bond-forming and bond-breaking processes are associated with single electrons.

Pericyclic Reactions

Reactions in which bond-forming or bond-breaking processes occur in a concerted way without forming any intermediate, passing through a cyclic transition state.

Substitution Reaction

A reaction in which one atom or group is replaced by another atom or group, involving the cleavage of one $\sigma$ bond and formation of another $\sigma$ bond at the same carbon atom.

Elimination Reaction

A reaction in which two groups are removed from adjacent atoms, breaking two $\sigma$ bonds and generating a new $\pi$ bond.

Addition Reaction

A reaction in which new groups add across multiple bonds, breaking a $\pi$ bond and forming two new $\sigma$ bonds.

Rearrangement Reaction

A reaction in which the bonds within a compound are reorganized without adding or removing atoms.

Redox Reaction

A process where one substance is oxidized by losing electrons and another is reduced by gaining electrons.

Nucleophilic Acyl Substitution

A substitution reaction occurring at an $sp^2$ hybridized carbonyl carbon of carboxylic acids and their derivatives, replacing a leaving group ($\text{Z}$) with a nucleophile ($\text{:Nu}^-$).

$\beta$-Elimination

An elimination process taking place at an $sp^3$ hybridized carbon atom where groups on adjacent carbons are removed (such as losing $\text{HX}$ from an alkyl halide with base or $\text{H}_2\text{O}$ from an alcohol with acid) to form an alkene.