Organic Chemistry - GOC & Hydrocarbon Revision

This set of vocabulary flashcards covers key concepts from Organic Chemistry Lecture 03 on General Organic Chemistry (GOC), focusing on electronic effects, resonance stability rules, and acidic strength in aromatic compounds.

EDG

Electron Donating Group; groups that donate electron density to the system.

EWG

Electron Withdrawing Group; groups that pull electron density away from the system.

+M Effect

The mesomeric effect where a group donates electrons through resonance, typically characterized by a lone pair in conjugation (e.g., $-NH_2$, $-OH$, $-OCH_3$).

-M Effect

The mesomeric effect where a group withdraws electrons through resonance, typically involving a $\text{=}$ bond in conjugation (e.g., $-NO_2$, $-CN$, $-CHO$, $-COOH$).

Stability of Resonance Structures: Neutral vs. Charged

A rule stating that neutral resonance structures are generally more stable than charged ones.

Stability of Resonance Structures: \text{\pi} bonds

The stability of a resonance structure increases as the number of \text{\pi} bonds increases.

Stability of Resonance Structures: Electronegativity

Stability is higher when a negative charge is on a more electronegative (EN) atom and a positive charge is on a less electronegative atom.

Extended vs. Cross Conjugation

Extended conjugation is generally more stable than cross conjugation.

Localized lone pair

A lone pair that does not participate in resonance.

Delocalized lone pair

A lone pair that participates in resonance.

Meta Position Rule for M-effect

The mesomeric effect ($+M$ or $-M$) does not operate at the meta position of a benzene ring.

Halogen Electronic Effects

For halogens like $Cl$, $Br$, and $I$, the inductive effect ($-I$) is stronger than the mesomeric effect ($+M$).

Ortho effect ($S.I.R$)

Steric Inhibition of Resonance; an effect in aromatic carboxylic acids where bulkiness at the ortho position increases acidic strength.

Acidic Strength - EWG Influence

Acidic strength increases with the presence of electron-withdrawing groups ($-M$ or $-I$).

Acidic Strength - EDG Influence

Acidic strength decreases with the presence of electron-donating groups ($+M$ or $+I$).