Question

Will my procedure for the production of 2-bromopentane from NaBr, 2-pentanol, and H2SO4 work? If not, how can I fix it to obtain high yield of my product? (Apparatuses and reagents listed in the procedure are the only ones available to use for this reaction)

1. Combine 7.00g NaBr and 3.00 g of 2-pentanol into a reaction flask that is in cold water. Slowly add, 12 mL of H2SO4 to the flask.

2. Set up a reflux apparatus and reflux the mixture for 45 minutes. After reflux, let cool to room temperature.

3. Pour mixture into separatory funnel. Wash with 15mL of H2O. Obtain organic layer.

4. Wash organic layer twice with 2 20mL portions of NaHCO3. Obtain organic layer.

5. Dry with sodium sulfate. Filtrate out sodium sulfate and obtain product.

6. Possible distillation?

Answer 1

The production of 2-bromopentane from NaBr, 2-pentanol, and H₂SO₄ work is correct but the highy yield of product depends upon many factors such as Varying amounts, conditions and procedural steps.

To overcome activation energy barrier for the reaction refluxing and addition of sulphuric acid is necessary otherwise reaction will not takes place.i.e.Combine 7.00g NaBr and 3.00 g of 2-pentanol into a reaction flask that is in cold water. Slowly add, 12 mL of H₂SO₄ to the flask. Set up a reflux apparatus and reflux the mixture for 45 minutes. After reflux, let cool to room temperature.

Note: To increase the product yield add more than 2 equimolar amount of NaBr

And Pour mixture into separatory funnel. Wash with 15mL of H₂O. Obtain organic layer. Wash organic layer twice with two 20mL portions of NaHCO₃. Obtain organic layer. Dry with sodium sulfate. Filtrate out sodium sulfate and obtain product.

Before Distillation use separate funnels would result into excess of NaBr crystals and then distillation which will result into higher yield.

Note : Due to low boling point of product.i.e. 2-bromopentane reflux was conducted with caution and at minimal temeratures to avoid scorching the product