Chapter 16, Problem 1Q

Which experimental method would you recommend for the preparation of 1-bromooctane and of t-butyl bromide?

Interpretation Introduction

Interpretation: The experimental method for the preparation of 1-bromooctane and t-butyl bromide needs to be explained.

Concept Introduction: Organic synthesis is a branch of chemical synthesis where the preparation of only organic compounds is studied. Compared to inorganic compounds, organic compounds are more complex. There are several methods for the preparation of an organic compound, but the best experimental method is the one that has fewer steps and gives more yield to the organic compound.

Explanation of Solution

Preparation of 1-bromooctane:

In organic synthesis, 1-bromooctane is an important intermediate. It is soluble in ether and ethanol. It is used for the synthesis of pesticides, surfactants, and organic dyes. There are the following steps involved in the preparation of 1-bromooctane:

1. 250 mL of a three-necked flask is taken with a thermostat and stirring machine.
2. In the same flask, n-octanol and sulfated zirconia-zincoxide are taken in the desired amount.
3. After that hydrobromic acid (40 %) is added slowly to the mixture and it is then stirred well.
4. Due to stirring, the temperature of the mixture increases.
5. In the next step, a saturated sodium bicarbonate solution is added to the reaction mixture and it is cooled to room temperature.
6. The resulting mixture is then separated and washed many times with deionized water until a neutral liquid is obtained.
7. The 1-bromooctane produced can be tested by gas chromatography.

Preparation of t-butyl bromide:

The following steps are involved in the preparation of t-butyl bromide:

1. In the first step of preparation, 1 mol of tert-butyl alcohol is reacted with 1.25 mol of HBr.
2. The obtained mixture is then boiled which results in the distilled volatile tert-butyl bromide.
3. The crude tert-butyl bromide obtained in step 2 is shaken with cold sulphuric acid (1/5^th volume) in order to dissolve the ether formed as a by-product.
4. In the next step, the product is washed with water and sodium bicarbonate to get it free from acid.
5. It is washed again with water and dried over calcium chloride.