Halogenoalkanes

• What is the general formula of halogenoalkanes?

  $\text{CH}_{2n + 1}\text{X}$
• Halogenoalkanes are more reactive than alkanes due to the presence of a polar bond.
• Match the use with the halogenoalkane property:

  Refrigerants ↔️ Low boiling point

  Solvents ↔️ Dissolve non-polar substances

  Pharmaceuticals ↔️ Biological activity
• Halogenoalkanes are named using the prefix chloro-, bromo-, or iodo- followed by the parent alkane name.
• If there are three or more carbon atoms in a halogenoalkane, the position of the halogen must be indicated
• What is the IUPAC name for CH3CH₂Br?

  Bromoethane
• Position isomers of halogenoalkanes have the same molecular formula but different positions of the halogen atom.
• If two different halogens are present in a molecule, they are named in alphabetical
• What is the IUPAC name for CH3CICHCl₂?

  1,1,2-trichloroethane
• A nucleophile is defined as an electron pair donor.
• Curly arrows in reaction mechanisms show the movement of a pair of electrons
• What happens to the C-Halogen bond in nucleophilic substitution?

  Breaks by heterolytic fission
• Match the common nucleophile with its chemical formula:

  Hydroxide ion ↔️ OH

  Cyanide ion ↔️ CN

  Ammonia ↔️ NH3
• What type of reaction occurs when halogenoalkanes react with aqueous hydroxides?

  Hydrolysis
• Sodium hydroxide solution is a common reagent used in the hydrolysis of halogenoalkanes.
• What are the organic products of the reaction between bromoethane and OH-

  Ethanol and Br-
• The hydrolysis of halogenoalkanes follows a nucleophilic substitution mechanism.
• Halogenoalkanes react with potassium cyanide to form nitriles
• What is the general equation for the reaction of a halogenoalkane with KCN?

  R-Hal + KCN → R-CN + K+Hal-
• Reacting a halogenoalkane with cyanide increases the length of the carbon chain.
• The nucleophile in the reaction between halogenoalkanes and KCN is the cyanide
• What is the IUPAC name for the organic product formed in the reaction between chloromethane and KCN?

  Ethanenitrile
• Halogenoalkanes react with excess ammonia to form amines.
• The general equation for the reaction of a halogenoalkane with excess ammonia is R-X + 2NH3 → R-NH₂ + NHX
• What is the organic product formed in the reaction between bromoethane and excess ammonia?

  Ethylamine
• Ammonia acts as a nucleophile in its reaction with halogenoalkanes.
• In the reaction of halogenoalkanes with ammonia, the halogen atom is replaced by an amino
• Outline the mechanism for the reaction between 2-iodobutane and excess ammonia.

  $\text{H}_{3}\text{C - CH}_{2}\text{ - CH - CH}_{3}\text{ + NH}_{3} \rightarrow \text{H}_{3}\text{C - CH}_{2}\text{ - CH - CH}_{3} \text{ + I}^{ - }$
• What does the rate of nucleophilic substitution in halogenoalkanes depend on?

  Carbon-halogen bond enthalpy
• Arrange the carbon-halogen bonds in order of decreasing bond enthalpy:

  1️⃣ C-F

  2️⃣ C-Cl

  3️⃣ C-Br

  4️⃣ C-I
• The C-I bond is the easiest carbon-halogen bond to break due to its lowest bond enthalpy.
• What precipitate forms during the hydrolysis of halogenoalkanes with silver nitrate?

  Silver halide
• Using halogenoalkanes with different chain lengths ensures a fair test in hydrolysis reactions.

  False
• Match the halogenoalkane with the color of the precipitate formed during hydrolysis with silver nitrate:

  1-chlorobutane ↔️ White

  1-bromobutane ↔️ Cream

  1-iodobutane ↔️ Yellow
• Arrange the relative rates of hydrolysis of halogenoalkanes from fastest to slowest:

  1️⃣ Iodoalkane

  2️⃣ Bromoalkane

  3️⃣ Chloroalkane
• Why is the C-I bond the easiest carbon-halogen bond to break?

  Lowest bond enthalpy
• In an elimination reaction, a halogenoalkane reacts to form an alkene
• Elimination reactions require sodium hydroxide under reflux conditions.
• What atom from an adjacent carbon atom is removed during an elimination reaction?

  Hydrogen
• Arrange the steps of the elimination reaction of 2-iodobutane to form but-1-ene:

  1️⃣ Removal of halogen atom

  2️⃣ Removal of hydrogen atom

  3️⃣ Formation of double bond