Alcohols - Typical Examples Of Periodate Oxidation

Alcohols - Typical examples of periodate oxidation

Periodate oxidation is a chemical reaction that can be used to oxidize alcohols.
In this process, the alcohol is converted into a carbonyl compound.
Let’s have a look at some typical examples of periodate oxidation.

Example 1: Oxidation of Primary Alcohol

Primary alcohols can be oxidized to aldehydes by periodate oxidation.
For example, when ethanol is oxidized using periodate, it forms acetaldehyde.
The reaction can be represented as follows: CH3CH2OH + HIO4 -> CH3CHO + H3IO6

Example 2: Oxidation of Secondary Alcohol

Secondary alcohols can be oxidized to ketones by periodate oxidation.
Let’s take the example of isopropanol.
When isopropanol is oxidized using periodate, it forms acetone.
The reaction can be represented as follows: (CH3)2CHOH + HIO4 -> (CH3)2CO + H3IO6

Example 3: Oxidation of Tertiary Alcohol

Tertiary alcohols cannot be oxidized by periodate oxidation.
This is due to the absence of a hydrogen atom attached to the carbon with the hydroxyl group.
Let’s take the example of tert-butanol.
When tert-butanol is treated with periodate, no oxidation occurs.
The reaction can be represented as follows: (CH3)3COH + HIO4 -> No reaction occurs

Mechanism of Periodate Oxidation

The mechanism of periodate oxidation involves the formation of an intermediate complex.
The hydroxyl group of the alcohol attacks the triiodide ion, forming an ester-like intermediate.
This intermediate then decomposes to form the carbonyl compound.
The overall reaction can be represented as follows: RCH2OH + HIO4 -> RCHO + H3IO6

Stereochemistry in Periodate Oxidation

Periodate oxidation can lead to changes in the stereochemistry of the starting alcohol.
For example, if the starting alcohol is optically active, the product may be obtained as a racemic mixture.
This is due to the attack of the hydroxyl group on the triiodide ion, which can happen from either side of the molecule.
Therefore, stereochemistry should be considered while interpreting the results of periodate oxidation reactions.

Applications of Periodate Oxidation

Periodate oxidation has various applications in organic synthesis.
It can be used to selectively oxidize primary or secondary alcohols in the presence of other functional groups.
This selective oxidation allows the precise modification of complex molecules.
Periodate oxidation reactions are also used in the analysis of carbohydrate structures.

Limitations of Periodate Oxidation

While periodate oxidation is a useful method for oxidizing alcohols, it has some limitations.
Tertiary alcohols cannot be oxidized by periodate oxidation.
Additionally, certain functional groups, such as double bonds or aromatic rings, can interfere with the reaction.
Careful consideration of these limitations is necessary for successful application of periodate oxidation.

Summary

Periodate oxidation is a chemical reaction used to oxidize alcohols.
Primary alcohols are oxidized to aldehydes, while secondary alcohols are oxidized to ketones.
Tertiary alcohols cannot be oxidized by periodate oxidation.
The reaction involves the formation of an intermediate complex, followed by decomposition to form the carbonyl compound.
Stereochemistry and limitations should be considered while interpreting the results of periodate oxidation reactions.

References

Organic Chemistry, Francis A. Carey, Robert M. Giuliano (2018)
Advanced Organic Chemistry: Part B: Reaction and Synthesis, Francis A. Carey, Richard J. Sundberg (2007)
Advanced Organic Chemistry, Jerry March (2007)

Primary Alcohol Oxidation

Primary alcohols undergo periodate oxidation to form aldehydes.
Example: Oxidation of ethanol with periodate leads to the formation of acetaldehyde.
Equation: CH3CH2OH + HIO4 → CH3CHO + H3IO6

Secondary Alcohol Oxidation

Secondary alcohols can be oxidized to ketones using periodate oxidation.
Example: Oxidation of isopropanol with periodate gives acetone as the product.
Equation: (CH3)2CHOH + HIO4 → (CH3)2CO + H3IO6

Tertiary Alcohol Oxidation

Tertiary alcohols cannot be oxidized by periodate oxidation.
Example: Oxidation of tert-butanol with periodate does not yield any product.
Equation: (CH3)3COH + HIO4 → No reaction occurs

Mechanism of Periodate Oxidation

Periodate oxidation proceeds through the formation of an ester-like intermediate.
The hydroxyl group attacks the triiodide ion, leading to the formation of the intermediate.
The intermediate then decomposes, yielding the carbonyl compound.
Overall equation: RCH2OH + HIO4 → RCHO + H3IO6

Stereochemistry in Periodate Oxidation

Periodate oxidation can cause stereochemical changes in the starting alcohol.
If the starting alcohol is optically active, the product may be obtained as a racemic mixture.
Stereochemistry is important to consider when interpreting the results of periodate oxidation reactions.

Applications of Periodate Oxidation

Periodate oxidation has applications in organic synthesis.
It allows for the selective oxidation of alcohols in the presence of other functional groups.
This selectivity enables precise modifications of complex molecules.
Periodate oxidation reactions are also used in carbohydrate structure analysis.

Limitations of Periodate Oxidation

Tertiary alcohols cannot be oxidized by periodate oxidation.
Certain functional groups, such as double bonds or aromatic rings, can interfere with the reaction.
These limitations need to be considered for successful application of periodate oxidation.

Summary of Periodate Oxidation

Periodate oxidation is a useful method for oxidizing alcohols.
Primary alcohols are converted to aldehydes, while secondary alcohols are converted to ketones.
Tertiary alcohols cannot be oxidized by periodate oxidation.
The reaction proceeds through an intermediate formation and subsequent decomposition.
Stereochemistry and limitations must be considered for interpreting the results.

References

Organic Chemistry, Francis A. Carey, Robert M. Giuliano (2018)
Advanced Organic Chemistry: Part B: Reaction and Synthesis, Francis A. Carey, Richard J. Sundberg (2007)
Advanced Organic Chemistry, Jerry March (2007)

Factors Affecting Periodate Oxidation

The rate of periodate oxidation can be influenced by various factors.
Temperature: Higher temperatures generally increase the reaction rate.
Concentration of Periodate: Increasing the concentration of periodate can enhance the oxidation reaction.
Solvent: The choice of solvent can impact the reaction rate and selectivity.
pH: The reaction rate can be affected by the pH of the solution.
Catalysts: Certain catalysts can be used to accelerate the reaction.

Example of Factors Affecting Periodate Oxidation

Let’s consider the oxidation of a primary alcohol, such as ethanol, to acetaldehyde using periodate.
At higher temperatures, the reaction rate would be faster, resulting in a quicker conversion of ethanol to acetaldehyde.
If the concentration of periodate is increased, the oxidation reaction will proceed more rapidly.
The choice of solvent can also affect the reaction rate and selectivity.
pH and catalysts can further influence the efficiency of the periodate oxidation reaction.

Oxidation of Alcohols: PCC and PDC Reagents

Besides periodate oxidation, other reagents can also oxidize alcohols.
One such example is the PCC (pyridinium chlorochromate) reagent.
PCC is commonly used to selectively oxidize primary alcohols to aldehydes.
Another example is the PDC (pyridinium dichromate) reagent, which can oxidize primary and secondary alcohols to either aldehydes or ketones, respectively.

Example: Oxidation of Alcohol using PCC

Let’s consider the oxidation of 2-propanol to propanal using PCC.
The reaction proceeds as follows: (CH3)2CHOH + PCC -> (CH3)2CHO + CrO3 + HCl

Example: Oxidation of Alcohol using PDC

Now let’s consider the oxidation of ethanol to acetaldehyde using PDC.
The reaction can be represented as: CH3CH2OH + PDC -> CH3CHO + CrO3 + HCl

Differences between Periodate Oxidation and PCC/PDC Oxidation

Periodate oxidation is selective for primary and secondary alcohols, while PCC and PDC reagents can oxidize both primary and secondary alcohols.
Periodate oxidation results in the formation of aldehydes or ketones, depending on the alcohol type.
PCC and PDC reagents directly convert primary alcohols to aldehydes and secondary alcohols to ketones.
The choice between periodate oxidation and PCC/PDC oxidation should be based on the specific requirements of the reaction.

Applications of PCC and PDC Oxidation

PCC and PDC oxidations are widely employed in organic synthesis and laboratory procedures.
These oxidations are often used for the conversion of alcohols to carbonyl compounds in various research and industrial applications.
PCC and PDC oxidations are performed under mild conditions and are compatible with many other functional groups.

Summary

Periodate oxidation, PCC, and PDC oxidations are methods used to selectively convert alcohols into carbonyl compounds.
Periodate oxidation is specific for primary and secondary alcohols, while PCC and PDC oxidations can target both primary and secondary alcohols.
The choice of oxidation method depends on the desired product and reaction conditions.
Factors such as temperature, concentration, solvent, pH, and catalysts can influence the efficiency of these reactions.
Periodate oxidation, PCC, and PDC oxidations find applications in organic synthesis and various chemical processes.

References

Organic Chemistry, Francis A. Carey, Robert M. Giuliano (2018)
Advanced Organic Chemistry: Part B: Reaction and Synthesis, Francis A. Carey, Richard J. Sundberg (2007)
Advanced Organic Chemistry, Jerry March (2007)