What is the reaction type when water is added to a double bond forming an alcohol?
Question:
What is the reaction type when water is added to double bond-forming alcohol?
Double Bonds:
A double bond is a type of covalent bond. These bonds can exist between different elements and are commonly seen in alkenes. A double bond is stronger that a single bond. It is also shorter than a single bond.
Answer and Explanation: 1
Consider a compound containing a double bond say propene. When the water molecule is added to the propene molecule, propan-2-ol is formed as a product in the presence of sulphuric acid.
The reaction of propene and water molecule in the presence of sulphuric acid occurs as
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This reaction is also called as hydration of alkenes.
Mechanism:
Step 1: Formation of a carbocation.
In the first step, secondary carbocation is formed. The active site of propene that involves in a reaction is a double bond.
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Step 2: Nucleophilic attack of a water molecule on carbocation.
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In this step, the water molecule attacked the secondary carbocation.
Step 3: Deprotonation
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In this step, a proton is removed and propan-2-ol is formed as a product.
This reaction proceeds via the carbocation mechanism and follows the Markovnikov rule. According to the Markovnikov rule, the negative part of the attacking reagent goes to that carbon atom that contains less number of the hydrogen atom. That's why propan-2-ol is formed as a product instead of propan-1-ol.
Thus, the addition reaction occurs when a water molecule is added to the double bond forming alcohol.
Learn more about this topic:
from
Chapter 18 / Lesson 11Learn about addition reactions in organic chemistry. Understand the definition of an addition reaction and its mechanism, and see addition reaction examples.