Haloalkanes and Haloarenes Class 12 Chemistry

Flashcards covering key concepts from Haloalkanes and Haloarenes in Class 12 Chemistry.

SN1 mechanism

A nucleophilic substitution reaction mechanism where a carbocation is formed as an intermediary.

Nucleophilicity

The tendency of a species to donate a pair of electrons to form a bond.

Benzyl Chloride

A compound that undergoes nucleophilic substitution exclusively by the SN1 mechanism due to stabilization by resonance.

Carbocation Stability

The relative stability of a carbocation, with tertiary being more stable than secondary and primary.

Reactivity Order of C—X Bonds

The increasing order of reactivity towards nucleophiles in C—X bonds follows the stability of formed carbocations.

m-Xylene and Br2 Reaction

A reaction where products are formed due to steric hindrance with the o- and p-directing methyl groups.

Racemisation

The formation of a racemic mixture during a nucleophilic substitution reaction when a chiral compound undergoes reaction.

Non-Polar Solvents

Solvents that favor nucleophilic substitution reactions due to their ability to stabilize carbocations.

Benzyne Mechanism

A mechanism that involves the substitution of an aromatic compound usually under specific reaction conditions.

Dihalogen Derivative

A compound containing two halogen atoms which may undergo reactions with KOH to produce a hydrocarbon.

Alkyl Fluoride Synthesis

Best accomplished via the Swartz reaction using alkyl halides and silver salts.

Chiral Compounds

Compounds that can exist in two enantiomeric forms due to the presence of a chiral carbon.

Haloalkane

A compound containing a halogen atom attached to an sp3 hybridised carbon atom.

Optically Active Compound

A compound that can rotate plane-polarized light due to its chiral nature.

Electrophilic Substitution

A chemical reaction in which an electrophile replaces a substituent in an aromatic compound.

SN2 mechanism

A type of nucleophilic substitution where the rate depends on both the nucleophile and the substrate.

Synthesis of Alkyl Halides

Can be achieved through various reactions including halogenation and nucleophilic substitution.

Finkelstein Reaction

A method to convert alkyl bromides to alkyl iodides using sodium iodide.

Chloropicrin

A compound formed by the reaction of nitric acid with chlorobenzene.

Structural Isomers

Compounds with the same molecular formula but different connectivity of atoms.

Electrophiles

Species that accepts an electron pair from a nucleophile to form a bond.

SN1 Reaction Characteristics

Leads to racemisation and occurs in two steps, with formation of a carbocation.

KCN Reactivity

Reacts with alkyl halides to form isocyanides, highlighting ambident nucleophilicity.

Gem-Dihalides

Compounds containing two halogen atoms attached to the same carbon atom.

Tyrosine Mechanism

Refers to the reaction mechanism involving a functional group in aromatic compounds.

Nucleophilic Aromatic Substitution

A substitution reaction where nucleophiles attack aromatic compounds that typically contain electron-withdrawing groups.

Elimination Reaction

A reaction where a molecule loses atoms or groups to form a double bond.

Grignard Reagent Formation

Created by the reaction of an alkyl halide with magnesium in dry ether.

Density Inequality in Haloalkanes

Higher molecular weight haloalkanes generally have higher densities.

Hydrolyzed Chloromethane

Reacts with ammonia to yield methanamine.

Nucleophilic Substitution by Hydroxide Ion

Typically yields a racemic mixture in secondary halides due to the creation of a planar carbocation.

Resonance Stabilized Carbocation

A carbocation that is stabilized by resonance, increasing its reactivity.

Ambident Nucleophiles

Nucleophiles that can react at two different sites to form different products.

Optical Rotation

The rotation of plane-polarized light by chiral compounds.

Markovnikov's Addition

Refers to the addition of HX to alkenes that results in the formation of the more substituted alkyl halide.

Electrophilic Addition vs. Substitution

Electrophilic addition forms adducts, while electrophilic substitution replaces existing groups.

Tyrosine Effects

Refers to the substituent effects on nucleophilicity in aromatic compounds.

Molecularity of SN1 Reactions

The molecularity of SN1 reactions is two, as it involves two species in the rate-determining step.

Chirality in Compounds

The geometric property of a molecule having distinguishable non-superimposable mirror images.

Hydroxyl Group Reactivity

Hydroxyl groups increase the reactivity of compounds in nucleophilic substitution.

Elimination Reaction Conditions

Favorable conditions for elimination reactions usually involve strong bases or heat.

Stabilization of Carbocations

Arises from hyperconjugation and resonance effects in more substituted carbocations.

Benzyl Group Reactivity

The benzyl group stabilizes carbocations and enhances their reactivity towards nucleophiles.

Formation of Racemic Mixtures

Occur in reactions involving chiral centers without a controlling factor for stereochemistry.

Chemical Properties of Haloalkanes

Include reactivity, boiling points, and molecular densities, which vary with structure.

Electron-Withdrawing Groups

Groups that stabilize negative charge on the adjacent atoms, increasing reactivity.

SN1 vs. SN2 Comparison

SN1 reactions are unimolecular and form carbocations, whereas SN2 reactions are bimolecular and involve direct displacement.

Reactivity of Halides

Varies across primary, secondary, and tertiary structures; tertiary halides react fastest in SN1 reactions.

Solvent Effects on Nucleophilic Substitution

Polar protic solvents stabilize ions; non-polar solvents favor SN1 mechanisms.

Hydrogen Bonding Effects

Influences the boiling points and solubility of haloalkanes in water.

Substituent Effects on Aromatic Halides

Electron-donating groups increase nucleophilicity, while electron-withdrawing groups decrease nucleophilicity.

Hydrolysis of Haloalkanes

React with water or alcohol to form alcohols, typically via SN1 or SN2 mechanisms.

Reaction of Ethyl Halide

Involves reagents and conditions that dictate the product's molecular structure.

Structure of Alkyl Halides

Characterized by the nature of the alkyl group and halogen attached, impacting reactivity.

Nucleophile Strength Order

Follows I− > Br− > Cl− > F− due to electronegativity and bond strength.