Organic Reactions and Preparations: Synthesis, Mechanisms, and Functional Groups

Vocabulary practice flashcards covering introductory concepts in organic synthesis, reaction mechanisms, polar and nonpolar reaction types, and carbonyl functional group transformations.

Organic synthesis

The set of methods and strategies chemists use to construct organic molecules from simpler starting materials; derived from the Greek word synthesis, meaning "put together."

Friedrich Wöhler (1828)

Reported the laboratory synthesis of urea, establishing an early milestone in the history of organic synthesis.

Hermann Kolbe (1845)

Coined the word "synthesis" and successfully synthesized acetic acid.

Emil Fischer (1890)

Accomplished one of the most remarkable syntheses of the 19th century by synthesizing glucose.

Electronegativity

The power of an atom in a molecule to attract electrons to itself; rated on an arbitrary scale where $F = 4.0$ and $Cs = 0.7$.

Hybridization effect on electronegativity

Because $s$ orbitals have substantial electron density at the nucleus while $p$ orbitals have a node, higher percent $s$ character holds electrons closer to the nucleus, increasing effective electronegativity in the order: $sp^3d^2 < sp^3d < sp^3 < sp^2 < sp$.

Resonance (mesomerism)

The use of two or more Lewis structures differing only in the placement of $\pi$ or nonbonding electrons to describe bonding in a molecule, providing extra stability through electron delocalization.

Polar (ionic) reactions

Reactions in which bond-forming or bond-breaking processes involve the movement of electron pairs.

Radical reactions

Reactions in which bond-forming or bond-breaking processes involve the movement of single unpaired electrons.

Pericyclic reactions

Reactions in which bond-forming and bond-breaking processes take place simultaneously in a concerted manner through a cyclic transition state without generating intermediates.

Substitution reaction

A reaction where one atom or group is replaced by another atom or group, involving breaking one $\sigma$ bond and forming a new $\sigma$ bond at the same carbon atom.

Elimination reaction

A reaction where two groups are removed from a starting material, resulting in the cleavage of two $\sigma$ bonds and the formation of a new $\pi$ bond between adjacent atoms.

Addition reaction

A reaction where a $\pi$ bond is broken to add new atoms or groups across adjacent carbons, forming two new $\sigma$ bonds; structurally the exact opposite of an elimination reaction.

Rearrangement reaction

A reaction where the chemical bonds within a compound are reorganized without adding or removing atoms.

Functional group

An atom, group of atoms, or specific bond that imparts characteristic chemical properties and predictable reactivity to an organic molecule.

Functional group transformation

The process of converting one functional group into another through standard reaction types such as substitution, addition, elimination, oxidation, or reduction using specific reagents.

Carbonyl group

A functional group consisting of a carbon atom double-bonded to an oxygen atom ($C=O$), where the $sp^2$-hybridized carbon adopts a trigonal planar geometry with bond angles of approximately $120^\circ$.

Carbonyl carbon

The electrophilic (Lewis acidic) site of a carbonyl group bearing a partial positive charge ($\delta+$) due to polarization toward the electronegative oxygen, making it susceptible to nucleophilic attack.

Carbonyl oxygen

The nucleophilic (Lewis basic) site of a carbonyl group bearing a partial negative charge ($\delta-$), which reacts with electrophiles and participates in hydrogen bonding with hydrogen-bond donors.

Nucleophilic addition (carbonyl compounds)

A reaction characteristic of aldehydes and ketones in which a nucleophile attacks the carbonyl carbon because the attached $-H$ or alkyl/aryl group ($-R$) cannot act as a leaving group.

Nucleophilic acyl substitution

A two-step pathway typical of carboxylic acid derivatives where a nucleophile attacks the carbonyl carbon to form a tetrahedral intermediate, which then expels a stable leaving group to regenerate the carbonyl group.

Tetrahedral intermediate

An $sp^3$-hybridized intermediate formed when an attacking nucleophile adds to the planar $sp^2$ carbonyl carbon of a carboxylic acid derivative.

Alpha-carbon ($\alpha$-carbon)

The carbon atom positioned directly adjacent to a carbonyl group, bearing acidic hydrogens that can be deprotonated by base.

Enolate ion

A resonance-stabilized anion formed by the deprotonation of an $\alpha$-hydrogen by a base, with the negative charge delocalized over the $\alpha$-carbon and the carbonyl oxygen.

Alpha-substitution reaction

A reaction in which an acidic hydrogen at the $\alpha$-carbon of a carbonyl compound is replaced by an electrophile via an intermediate enol or enolate ion.