So I was asked to write the overall equation for Br2 in Dichloromethane with Cyclohexene. I can kinda fudge the overall reaction because I know the general reaction of halogens with a double bond, but I am wondering why is the Br2 in the Dichloromethane in the first place. And I'm supposed to write down each additive step before the overall reaction...so does Br2 react with Dichloromethane BEFORE it does so with Cychlohexene???
I believe the dichloromethane is a solvent for the Br2.
To understand why Br2 is in dichloromethane in the first place and how it reacts with cyclohexene, it is helpful to consider the properties and behavior of both compounds.
Firstly, dichloromethane (CH2Cl2) is a common organic solvent that is often used in organic reactions. It is a nonpolar solvent, meaning it does not have a net dipole moment due to the symmetry of its molecular structure. This property makes it suitable for dissolving a wide range of organic molecules, including nonpolar and moderately polar compounds.
Bromine (Br2) is a halogen element that exists as a diatomic molecule in its standard state. It is a reddish-brown liquid and a strong oxidizing agent. Bromine has a strong affinity for electron-rich species, particularly double bonds, and readily undergoes addition reactions with them.
When Br2 is mixed with dichloromethane, the solvent serves as a medium to facilitate the reaction between Br2 and cyclohexene. Br2 molecules will be dissolved in dichloromethane due to its solubility in nonpolar solvents. This mixture allows for the bromine to react with cyclohexene in a controlled manner.
Now, let's discuss the steps involved in the overall reaction:
1. The first step involves the dissolution of Br2 in dichloromethane. This occurs due to the solubility of Br2 in nonpolar solvents. The equation for this step would be:
Br2 (l) + CH2Cl2 (l) → Br2 in CH2Cl2 (solution)
2. Once Br2 is dissolved in dichloromethane, it becomes reactive towards cyclohexene. The double bond in cyclohexene acts as an electron-rich site that can attack the electron-deficient bromine. This leads to the addition of the bromine molecule across the double bond, forming a cyclic bromonium ion intermediate. The equation for this step is:
Br2 in CH2Cl2 (solution) + Cyclohexene (C6H10) → Bromonium ion intermediate
3. In the final step, the bromonium ion intermediate is opened up by a chloride ion (Cl-) from the dichloromethane solvent, facilitating the formation of the final product. This results in the addition of a bromine atom and a chloride atom to the cyclohexene molecule, leading to the formation of vicinal dibromide. The equation for this step is:
Bromonium ion intermediate + Cl- (from CH2Cl2) → Dibromocyclohexane (product)
It is important to note that these steps occur sequentially and that dichloromethane primarily acts as a solvent in this reaction, facilitating the reaction between Br2 and cyclohexene by providing an appropriate medium for the reactants to come into contact.
By taking into account these steps and considering the reactivity of bromine towards double bonds, you can write the overall equation for the reaction:
Br2 in CH2Cl2 + Cyclohexene → Dibromocyclohexane