Competing Nucleophiles Lab
Title: Competing Nucleophiles (Exp 24, pp 211-221, pp 808-823, pp 836-842)
Purpose:
The purpose of this experiment is to determine the nucleophilic strength of chloride and bromide ions as it reacts with 1-butanol (n-butyl) and 2-methyl-2-propanol (t-butyl alcohol) under SN1 and SN2 conditions.
Method:
40 g of ice and approximately 30 ml of sulfuric acid is cautiously added to a 100 mL beaker respectively. Weigh 7.6 g of ammonium chloride and 14.0 g of ammonium bromide and place it in another beaker, crushing the lumps until a powdery mixture remains. The powdery mixture is then transferred to a 125 mL Erlenmeyer flask. Add the ammonium salts into the sulfuric acid mixture. Heat is applied to dissolve the salt. Once the solution has fully dissolved, allow it to cool until the warm substance is touchable. A prolonged waiting period can cause the solution to recrystallize and this process would have to be repeated again. Place 6.0 mL of water in a 15 mL centrifuge tube marking the tube at the 6.0 mL level and replace the water with the solvent-nucleophile mixture. The tube is set aside for the t-butyl experiment. The remaining mixture is placed in a 25 mL round bottom flask.
Competitive Nucleophiles with 1- Butanol (n-butyl alcohol)
Assemble a reflux apparatus including the 25 mL round bottom flask and a heating mantle as a heat source. 5 mL of n-butyl alcohol is added to the flask by detaching the flask and adding the alcohol via a Pasteur pipet. Allow the mixture to boil at a temperature sustainable for a gentle boil for approximately 75 minutes. After this process has been completed, turn the heat off and allow the mixture to cool for approximately 10 minutes. Once ten minutes has elapsed, carefully place the flask into a cool water bath (without ice) until the mixture cools to room temperature. At this point, an organic layer should be visible. Transfer this solution into a separatory funnel. Drain most of the bottom aqueous layer into a beaker.
Purpose:
The purpose of this experiment is to determine the nucleophilic strength of chloride and bromide ions as it reacts with 1-butanol (n-butyl) and 2-methyl-2-propanol (t-butyl alcohol) under SN1 and SN2 conditions.
Method:
40 g of ice and approximately 30 ml of sulfuric acid is cautiously added to a 100 mL beaker respectively. Weigh 7.6 g of ammonium chloride and 14.0 g of ammonium bromide and place it in another beaker, crushing the lumps until a powdery mixture remains. The powdery mixture is then transferred to a 125 mL Erlenmeyer flask. Add the ammonium salts into the sulfuric acid mixture. Heat is applied to dissolve the salt. Once the solution has fully dissolved, allow it to cool until the warm substance is touchable. A prolonged waiting period can cause the solution to recrystallize and this process would have to be repeated again. Place 6.0 mL of water in a 15 mL centrifuge tube marking the tube at the 6.0 mL level and replace the water with the solvent-nucleophile mixture. The tube is set aside for the t-butyl experiment. The remaining mixture is placed in a 25 mL round bottom flask.
Competitive Nucleophiles with 1- Butanol (n-butyl alcohol)
Assemble a reflux apparatus including the 25 mL round bottom flask and a heating mantle as a heat source. 5 mL of n-butyl alcohol is added to the flask by detaching the flask and adding the alcohol via a Pasteur pipet. Allow the mixture to boil at a temperature sustainable for a gentle boil for approximately 75 minutes. After this process has been completed, turn the heat off and allow the mixture to cool for approximately 10 minutes. Once ten minutes has elapsed, carefully place the flask into a cool water bath (without ice) until the mixture cools to room temperature. At this point, an organic layer should be visible. Transfer this solution into a separatory funnel. Drain most of the bottom aqueous layer into a beaker.