Halogenalkanes

• What prefix is used for the halogen atom fluorine in halogenoalkane naming?


  Fluoro
• What is the prefix for the halogen atom chlorine in halogenoalkane naming?


  Chloro
• What is the prefix for the halogen atom bromine in halogenoalkane naming?


  Bromo
• What is the prefix for the halogen atom iodine in halogenoalkane naming?


  Iodo
• How are substituents listed in the naming of halogenoalkanes?


  Substituents are listed alphabetically
• What is the name of the compound with the structure shown as 1-bromopropane?


  1. bromopropane
• How can halogenoalkanes be classified?


  They can be classified as primary, secondary, or tertiary
• What determines whether a halogenoalkane is primary, secondary, or tertiary?


  It depends on the number of carbon atoms attached to the carbon atom adjoining the C-X functional group
• What type of reaction do halogenoalkanes undergo?


  They undergo nucleophilic substitution reactions
• What is a nucleophile?


  A nucleophile is an electron pair donor
• What happens during a substitution reaction of halogenoalkanes?


  A halogen atom is swapped for another atom or group of atoms
• What does the rate of substitution reactions depend on?


  It depends on the strength of the C-X bond
• What is the bond enthalpy of the C-I bond?


  238 kJ/mol
• What is the bond enthalpy of the C-Br bond?


  276 kJ/mol
• What is the bond enthalpy of the C-Cl bond?


  338 kJ/mol
• What is the bond enthalpy of the C-F bond?


  484 kJ/mol
• Which halogenoalkanes are the fastest and slowest to substitute?


  Iodoalkanes are the fastest, and fluoroalkanes are the slowest
• Why are fluoroalkanes very unreactive?


  Because the strength of the C-F bond is very high
• What do curly arrows represent in reaction mechanisms?


  Curly arrows show the movement of two electrons
• What is a primary halogenoalkane?


  One carbon is attached to the carbon atom adjoining the halogen
• What is a secondary halogenoalkane?


  Two carbons are attached to the carbon atom adjoining the halogen
• What is a tertiary halogenoalkane?


  Three carbons are attached to the carbon atom adjoining the halogen
• What is hydrolysis in the context of halogenoalkanes?


  Hydrolysis is the splitting of a molecule by a reaction with water
• What is the general reaction for hydrolysis of a halogenoalkane?


  CH3CH2X + H2O → CH3CH2OH + X- + H+
• What is the role of aqueous silver nitrate in comparing halogenoalkanes?


  It forms a silver halide precipitate with the halide leaving group
• What does the formation of a precipitate indicate in the context of halogenoalkanes?


  It indicates that the halide ion has left the halogenoalkane
• What is the precipitate formed when iodoalkane reacts with silver nitrate?


  AgI (s) - yellow precipitate
• What is the precipitate formed when bromoalkane reacts with silver nitrate?


  AgBr (s) - cream precipitate
• What is the precipitate formed when chloroalkane reacts with silver nitrate?


  AgCl (s) - white precipitate
• How does the strength of the C-X bond affect the rate of substitution reactions?


  The weaker the bond, the easier it is to break and the faster the reaction
• What is the change in functional group when halogenoalkane reacts with aqueous hydroxide ions?


  Halogenoalkane changes to alcohol
• What reagent is used in nucleophilic substitution with aqueous hydroxide ions?


  Potassium (or sodium) hydroxide
• What are the conditions for nucleophilic substitution with aqueous hydroxide ions?


  In aqueous solution and warm
• What happens when the solvent is changed to ethanol during nucleophilic substitution?


  An elimination reaction occurs
• How do tertiary halogenoalkanes undergo nucleophilic substitution differently?


  They form a carbocation intermediate before the nucleophile attacks
• Why are tertiary carbocations stabilized?


  They are stabilized by the electron-releasing methyl groups around them
• What is the change in functional group when halogenoalkane reacts with cyanide ions?


  Halogenoalkane changes to nitrile
• What reagent is used in nucleophilic substitution with cyanide ions?


  KCN dissolved in ethanol/water mixture
• What are the conditions for nucleophilic substitution with cyanide ions?


  Heating under reflux
• What is the change in functional group when halogenoalkane reacts with ammonia?


  Halogenoalkane changes to amine