Draw the mechainsm for the reaction (2methyl-1-butene +H2SO4 )in water solution –>2-methyl-2-butanol +sulfric acid+ water
The Correct Answer and Explanation is:
The reaction you’re asking about is an example of an electrophilic addition reaction, where 2-methyl-1-butene reacts with sulfuric acid (H₂SO₄) in water. The products are 2-methyl-2-butanol, sulfuric acid, and water. Here’s the mechanism broken down step-by-step:
- Protonation of the Alkene:
- The double bond in 2-methyl-1-butene is nucleophilic and attacks the proton (H⁺) from sulfuric acid. This leads to the formation of a carbocation intermediate.
- Since the carbocation will be more stable if formed at the more substituted carbon (the carbon next to the CH₃ group), the proton will add to the carbon atom that is less substituted (C1), forming a carbocation at the C2 position.
- Carbocation Formation:
- The resulting carbocation (on C2) is a secondary carbocation and can undergo rearrangement to form a more stable carbocation. In this case, there is no rearrangement, as the C2 carbocation is already relatively stable.
- Nucleophilic Attack by Water:
- Water, being a nucleophile, attacks the carbocation formed at C2. The oxygen atom of water donates a lone pair of electrons to the carbocation, forming an oxonium ion (C2-OH₂⁺).
- Deprotonation:
- The oxonium ion formed in step 3 is protonated, and this proton is lost to form the final product: 2-methyl-2-butanol.
- Sulfuric Acid Regeneration:
- The proton that was initially added to the alkene is now released during the deprotonation step. Therefore, the sulfuric acid catalyst is regenerated.
Reaction Summary:
The overall reaction involves electrophilic addition of H⁺ to 2-methyl-1-butene, followed by nucleophilic attack by water, leading to the formation of 2-methyl-2-butanol. This reaction also demonstrates the catalytic role of sulfuric acid, which is regenerated at the end of the reaction.
