The alkene which will give the same product with HBr in the absence as...
But-2-ene is the right answer as reacting it with HBr in presence and absence of peroxide will give 2-Bromo butane.
The alkene which will give the same product with HBr in the absence as...
Answer:
The alkene which will give the same product with HBr in the absence as well as in the presence of peroxide is 2-Methyl propene.
Explanation:
When HBr is added to an alkene in the absence of peroxide, the reaction follows the Markovnikov's rule, and the hydrogen atom attaches itself to the carbon atom having more hydrogen atoms already attached to it. In simple terms, the hydrogen atom adds to the carbon atom having more number of carbon atoms attached to it. On the other hand, when HBr is added to an alkene in the presence of peroxide, the reaction follows the Anti-Markovnikov rule, and the hydrogen atom attaches itself to the carbon atom having fewer hydrogen atoms already attached to it. In simple terms, the hydrogen atom adds to the carbon atom having fewer number of carbon atoms attached to it.
Now, let's look at the given options:
(a) 1-butene - In the absence of peroxide, HBr will add to the 1st carbon atom and in the presence of peroxide, HBr will add to the 2nd carbon atom. Hence, this option does not give the same product in the absence as well as in the presence of peroxide.
(b) 2-butene - In the absence of peroxide, HBr will add to the 2nd carbon atom and in the presence of peroxide, HBr will add to the 1st carbon atom. Hence, this option does not give the same product in the absence as well as in the presence of peroxide.
(c) 1-hexene - In the absence of peroxide, HBr will add to the 1st carbon atom and in the presence of peroxide, HBr will add to the 2nd carbon atom. Hence, this option does not give the same product in the absence as well as in the presence of peroxide.
(d) 2-Methyl propene - In the absence of peroxide, HBr will add to the 1st carbon atom and in the presence of peroxide, HBr will also add to the 1st carbon atom. Hence, this option gives the same product in the absence as well as in the presence of peroxide.
Therefore, the correct answer is 2-Methyl propene.