Question

In the addition of just 1 mole of bromine to 1 mole of hex-1-yne, should the hex-1-yne be added to a bromine solution or should the bromine be added to the hex-1-yne? Explain your answer.

Accepted Answer

Step 1: Understand the reaction mechanism. The addition of bromine (Br₂) to hex-1-yne is an electrophilic addition reaction. Hex-1-yne, being an alkyne, has a high electron density in its triple bond, making it nucleophilic and capable of attacking the electrophilic bromine molecule. Step 2: Recognize the reactivity of bromine. Bromine (Br₂) is a diatomic molecule that can act as an electrophile when its bond is polarized. This polarization occurs when bromine approaches the electron-rich triple bond of hex-1-yne. Step 3: Consider the practical aspect of the reaction. To ensure a controlled and efficient reaction, the bromine solution should be added dropwise to the hex-1-yne. This approach minimizes the risk of overreaction or side reactions, as bromine is highly reactive and can lead to the addition of more than one mole if not carefully controlled. Step 4: Explain the reasoning. Adding bromine to hex-1-yne allows for better control of the reaction stoichiometry, ensuring that only 1 mole of bromine reacts with 1 mole of hex-1-yne. If hex-1-yne were added to a bromine solution, the excess bromine could lead to further addition reactions, forming a tetrabromo product instead of the desired dibromo product. Step 5: Conclude the explanation. Therefore, to achieve the desired product (a dibromoalkene), bromine should be added to hex-1-yne in a controlled manner, typically dropwise, to ensure the reaction proceeds as intended.

In the addition of just 1 mole of bromine to 1 mole of hex-1-yne, should the hex-1-yne be added to a bromine solution or should the bromine be added to the hex-1-yne? Explain your answer.

Verified video answer for a similar problem:

Key Concepts

Electrophilic Addition

Reactivity of Alkynes

Solubility and Reaction Medium