Preparing 1-Bromobutane with Hydrobromic Acid
Questions:
1. How is hydrogen bromide prepared for use in the experiment?
2. What is the limiting reagent for the conversion of 1-butanol to 1-bromobutane and the theoretical yield of the product?
3. Is this reaction an SN1 or SN2 process? How can the mechanism be confirmed experimentally?
4. What are the structures of two possible side products that might form in this reaction?
5. What are the purposes of heating at reflux, simple distillation, and adding anhydrous sodium sulfate in the preparation?
6. What are the possible effects of inhaling excessive amounts of 1-butanol?
7. The flash points (°C) of 1-butanol and 1-bromobutane are _______ and _______ respectively.
8. What action should be taken if 1-butanol gets on the skin?
9. True (T) or False (F): Water is an appropriate medium for extinguishing fires involving 1-bromobutane.
Answers:
1. Hydrogen bromide is prepared by adding concentrated sulfuric acid to concentrated hydrobromic acid or by generating hydrobromic acid in situ using aqueous sodium bromide.
2. The limiting reagent for the conversion of 1-butanol to 1-bromobutane can be either 1-butanol or hydrogen bromide, depending on which is in excess. The theoretical yield of the product can be calculated based on the stoichiometry of the balanced equation.
3. This reaction is an SN2 process, confirmed by the concerted expulsion of the leaving group (water) by the nucleophilic bromide ion. Experimental confirmation of the mechanism can be done through kinetic studies and stereochemical analysis.
4. Two possible side products that might form in this reaction are an alkyl hydrogen sulfate (2) and a di-alkyl ether.
5. Heating at reflux is used to ensure continuous boiling and vaporization, simple distillation is for separating components based on boiling points, and adding anhydrous sodium sulfate is to remove water content from the reaction mixture.
6. Inhaling excessive amounts of 1-butanol can lead to symptoms like headache, dizziness, drowsiness, irritation of the respiratory tract, and in severe cases, unconsciousness.
7. The flash points of 1-butanol and 1-bromobutane are [insert values] and [insert values] respectively.
8. If 1-butanol gets on the skin, wash the affected area with soap and water, and seek medical attention if irritation persists.
9. False (F): Water is not an appropriate medium for extinguishing fires involving 1-bromobutane due to the organic nature of the compound.
Explanation:
Preparing 1-bromobutane involves the conversion of 1-butanol to an alkyl bromide using hydrogen bromide as a reagent. Understanding the reaction mechanism, side product formation, and safety precautions are essential in the experimental procedure.
Hydrogen bromide is prepared by adding concentrated sulfuric acid to concentrated hydrobromic acid or by generating hydrobromic acid in situ. The limiting reagent in the conversion process can be determined based on the stoichiometry of the reaction, with the theoretical yield calculated accordingly.
The reaction is an SN2 process, characterized by the nucleophilic attack of the bromide ion on the oxonium ion intermediate. Experimental verification of the mechanism can be conducted through various analytical techniques.
Side products like alkyl hydrogen sulfate and di-alkyl ether may form during the reaction, affecting the overall yield. Experimental techniques such as heating at reflux and simple distillation aid in the process, while safety measures should be taken to avoid inhaling excessive amounts of 1-butanol.
Understanding the properties and handling of 1-butanol and 1-bromobutane, including flash points and proper skin contact procedures, is crucial for a successful and safe experimental outcome.