Table of Contents
Dehydration of Alcohol Mechanism
Dehydration of alcohol is a process used to produce ethanol. In this process, an alcohol is heated with a dehydrating agent, such as sulfuric acid. The dehydration agent removes water from the alcohol, leaving behind ethanol.
| S.NO | CONTENT |
| 1 | INTRODUCTION |
| 2 | 3-STEP MECHANISM |
| 3 | MECHANISM OF DEHYDRATION |
| 4 | PRIMARY ALCHOHOL DEHYDRATION |
| 5 | SECONDARY ALCOHOL DEHYDRATION |
| 6 | TERTIARY ALCHOHOL DEHYDRATION |
| 7 | DEHYDRATION OF PRIMARY, SECONDARY, AND TERTIARY ALCOHOLS |
Dehydration can be performed in a 3-step mechanism:
1. The first step in dehydration of alcohols is the breaking of the C-O-H bond, which is catalyzed by a dehydrating agent. This step yields an alkene and water.
2. The second step is the removal of the hydrogen atom from the alkene, which is catalyzed by a dehydrating agent. This step yields an alkane and water.
3. The third step is the removal of the water molecule, which is catalyzed by a dehydrating agent. This step yields an alkane.
Mechanism of Dehydration of Alcohols
Dehydration of alcohols is a reaction in which an alcohol is converted into a ketone or aldehyde. The reaction is catalyzed by a strong acid, such as sulfuric acid. The mechanism of the reaction is as follows:
The acid protonates the alcohol, creating a carbocation. The carbocation then reacts with water to form a ketone or aldehyde.
Alcohol Dehydration Reaction
The dehydration reaction of alcohols is a substitution reaction in which an alcohol is converted into an alkyl halide. The mechanism involves the removal of a water molecule from the alcohol molecule.
A Protonated Primary Alcohol (Alkene)
In this example, the protonated primary alcohol is an alkene.
The protonated primary alcohol has the molecular formula CH 3 CH=CHCH 3 . It is a colorless liquid with an unpleasant odor. It is soluble in water and ethanol.
Alcohol Dehydration Mechanism with Example
When alcohol is consumed, it is absorbed into the bloodstream from the stomach and small intestine. The alcohol is then transported to the liver, where it is broken down (metabolized) into acetaldehyde and carbon dioxide.
Some of the acetaldehyde is further broken down into harmless water and carbon dioxide. However, a small amount of acetaldehyde is converted into a harmful chemical called acetic acid.
Acetic acid is toxic to the body and can damage organs, including the liver. It can also cause dehydration, which can lead to a number of health problems, including liver damage, heart problems, and brain damage.
Secondary Alcohol Dehydration
The dehydration of secondary alcohols to ketones is catalyzed by acid. In general, the reaction is favored by a strong acid, such as sulfuric acid, and is reversible. The dehydration of a secondary alcohol to a ketone proceeds via an enol intermediate.
The enol intermediate is stabilized by resonance, which results in a decrease in the energy of the transition state. This makes the dehydration of a secondary alcohol to a ketone more favorable than the dehydration of a primary alcohol to a ketone.
Tertiary Alcohol Dehydration
Tertiary alcohols can be dehydrated to ketones using acid catalysts, such as sulfuric acid or phosphoric acid. The dehydration reaction is shown below.
The ketone can then be reduced to an alcohol using a reducing agent, such as lithium aluminium hydride (LAH), as shown below.
This reduction reaction can also be used to convert a ketone to an alcohol.
Dehydration of Primary Secondary and Tertiary Alcohols
The dehydration of primary, secondary, and tertiary alcohols can be achieved through the use of various dehydrating agents, including sulfuric acid, phosphoric acid, and boron trifluoride.
The dehydration of a primary alcohol can be accomplished by passing the alcohol over a heated catalyst, such as sulfuric acid or phosphoric acid. In the presence of a dehydrating agent, the hydrogen atoms on the carbon adjacent to the hydroxyl group are removed, forming a carbonyl group.
The dehydration of a secondary alcohol can be accomplished by passing the alcohol over a heated catalyst, such as sulfuric acid or phosphoric acid. In the presence of a dehydrating agent, the hydrogen atoms on the carbon two carbons away from the hydroxyl group are removed, forming a ketone.
The dehydration of a tertiary alcohol can be accomplished by passing the alcohol over a heated catalyst, such as sulfuric acid or phosphoric acid. In the presence of a dehydrating agent, the hydrogen atoms on the carbon three carbons away from the hydroxyl group are removed, forming an aldehyde.
