Organic Chemistry: Reaction Types and Mechanisms

Comprehensive vocabulary flashcards covering chemical reaction types, reagents, bond fission mechanisms, and specific halogenoalkane reactions based on the lecture notes.

Addition Reaction

A chemical reaction where two molecules combine to form one product, typically involving the breaking of a double or triple bond.

Substitution Reaction

A reaction where one atom or functional group in a molecule is replaced by another atom or group, such as bromoethane reacting with $OH^-$ to form ethanol.

Reagent

A substance added to a chemical reaction to cause a reaction or to test for the presence of another substance, categorized as electrophiles, nucleophiles, or free radicals.

Electrophiles

Species that are electron-deficient and accept an electron pair to form a covalent bond; examples include $H^+$ and $NO_2^+$.

Nucleophiles

Species that donate an electron pair to form a covalent bond, typically being negatively charged or having lone pairs, such as $OH^-$, $CN^-$, $NH_3$, and $H_2O$.

Free Radicals

Highly reactive species with an unpaired electron formed by homolytic bond fission, such as chlorine radicals (Cl^ullet) or methyl radicals (CH_3^ullet).

Homolytic Fission

Bond breaking where each atom takes one electron from the shared pair, resulting in the formation of free radicals; represented by single-headed (fish-hook) arrows.

Heterolytic Fission

Bond breaking where both bonding electrons go to one of the atoms, resulting in the formation of ions; represented by full curly (double-headed) arrows.

Electrophilic Addition

A reaction where an electrophile (like ext{H}^{ ext{ iny $\delta$}+} in $HBr$) attacks an electron-rich double bond in an alkene to form a single product.

Free Radical Substitution

A reaction occurring in alkanes and halogens requiring UV light, consisting of initiation (forming radicals), propagation (chain reaction), and termination.

Halogenoalkane Polarity

A characteristic caused by halogens being more electronegative than carbon, drawing electron density away to form ext{C}^{ ext{ iny $\delta$}+} and ext{X}^{ ext{ iny $\delta$}-} regions.

Carbon-Halogen Bond Strength

The trend where atomic size increases down the group, making the C-F bond the strongest and the C-I bond the longest and weakest.

Halogenoalkane Reactivity

The reactivity trend determined by bond enthalpy, where the $C-I$ bond is more reactive than $C-Br$, $C-Cl$, and $C-F$ bonds.

Nucleophilic Substitution

A reaction type where a nucleophile attacks the electron-poor ( ext{ iny $\delta$}+) carbon in a halogenoalkane to displace the halogen as a halide ion.

Nitrile Formation

A nucleophilic substitution reaction where a halogenoalkane is heated under reflux with $KCN$ in ethanol, replacing the halogen with a $-CN$ group.

Amine Formation

A reaction where a halogenoalkane reacts with ammonia ($NH_3$) dissolved in ethanol when heated under pressure.

Reflux

The heating condition used when reacting halogenoalkanes with cyanide ions in ethanol to ensure the reaction goes to completion and produces a nitrile.