Nucleophilic Substitution: The reactivity of halogenated hydrocarbons

chemical equation showing generic reaction of a molecule that has a leaving group reacting with a nucleophile

During this activity students investigate the solubility and reactivity of n- and t- pentanol in water and hydrochloric acid.

Reactions with Sodium Iodide in Acetone Solution

a chemical eauation showing the production of an insoluble salt and an iodohydrocarbon from a generic chlorine or bromoine containing halohydrocarbon reacting with sodium iodide in acetone.

A solution (1 mL) of sodium iodide dissolved in acetone is added to eight test tubes.

Sodium iodide is soluble in acetone whereas sodium chloride and sodium bromide are not. Thus, the formation of a precipitate is evidence that the iodide displaced the leaving group, which then precipitated from solution.

A few drops of the following alkyl halides are added, one compound for one of each of the test tubes, to the first four test tubes.

1-chlorobutane
1-bromobutane
2-chlorobutane
2-bromobutane

A few drops of the following halohydrocarbons are added, one compound for one of each of the test tubes, to the second four test tubes.

2-chloro-2-methylpropane
1-chloro-2-butene
benzyl chloride (aka -chlorotoluene)
bromobenzene

Note: The test tube labeled 2-chloro-2-methylbutane is mislabeled. 2-Chloro-2-methylpropane is the chemical that was added to the reaction.

The mixtures that remained clear are transfered to a warm water bath (50 °C max).

Note: The test tube labeled 2-chloro-2-methylbutane is still mislabeled. 2-Chloro-2-methylpropane is the chemical that was added to the reaction.

Reactions with Ethanol in the Presence of Silver Nitrate

a chemical eauation showing the production of an insoluble silver salt and an ethyl ether from a generic chlorine or bromoine containing halohydrocarbon reacting with ethanol in the presence of silver nitrate.

A solution (1 mL) of silver nitrate dissolved in ethanol is added to eight test tubes.

Silver nitrate is soluble in ethanol, but silver chloride and silver bromide are not. The formation of a precipitate is evidence that a nucleophile (ethanol, which is also the solvent) has displaced the halogen leaving group.

A few drops of the following alkyl halides are added, one compound for one of each of the test tubes, to the first four test tubes.

1-chlorobutane
1-bromobutane
2-chlorobutane
2-bromobutane

A few drops of the following halohydrocarbons are added, one compound for one of each of the test tubes, to the second four test tubes.

2-chloro-2-methylpropane
1-chloro-2-butene
benzyl chloride (aka -chlorotoluene)
bromobenzene

Note: The test tube labeled 2-chloro-2-methylbutane is once again mislabeled. 2-Chloro-2-methylpropane is the chemical that was added to the reaction.

The mixtures that remaineded clear are transfered to a warm water bath (80 °C max).

Note: The test tube labeled 2-chloro-2-methylbutane is still mislabeled. 2-Chloro-2-methylpropane is the chemical that was added to the reaction.