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7.4.4.3.3 - Reimer-Tiemann reaction

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Introduction to the Reimer-Tiemann Reaction

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Teacher
Teacher

Today we are going to discuss the Reimer-Tiemann reaction. Can anyone tell me what happens to phenol when it reacts with chloroform in the presence of sodium hydroxide?

Student 1
Student 1

Isn't it something to do with adding a –CHO group?

Teacher
Teacher

Exactly! The Reimer-Tiemann reaction introduces a formyl group to the ortho position of the phenolic ring, resulting in salicylaldehyde.

Student 2
Student 2

So, what is the significance of the ortho position?

Teacher
Teacher

The ortho position allows for specific interactions that contribute to the structure and reactivity of the final product. This specificity is critical in synthetic chemistry.

Student 3
Student 3

Can we use this method for other aromatic compounds?

Teacher
Teacher

Good question! It primarily works with phenol. Other aromatic compounds often require different methods due to steric hindrance.

Teacher
Teacher

In summary, the Reimer-Tiemann reaction connects phenol to salicylaldehyde through a well-defined mechanism involving ortho substitution. Let's remember that phenol's electric properties are key here!

Mechanism of the Reimer-Tiemann Reaction

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Teacher
Teacher

Now, let’s delve into the mechanism of the Reimer-Tiemann reaction. Can anyone outline the steps we might expect in this process?

Student 4
Student 4

I think it starts with phenol losing a hydrogen ion to form phenoxide?

Teacher
Teacher

Correct! That’s the first step: the deprotonation of phenol creates the phenoxide ion. What happens next?

Student 1
Student 1

Then it reacts with chloroform, right? What does that produce?

Teacher
Teacher

Yes! That reaction leads to the formation of benzal chloride. It’s critical because this intermediate undergoes hydrolysis in the next step to yield our final product. Can someone explain what hydrolysis entails?

Student 2
Student 2

Hydrolysis is when water reacts with a substance to split it apart.

Teacher
Teacher

Precisely! The hydrolysis of benzal chloride in an alkaline medium forms salicylaldehyde. So we can summarize: the Reimer-Tiemann reaction involves deprotonation, electrophilic attack, and hydrolysis.

Applications of Salicylaldehyde

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Teacher
Teacher

So why is salicylaldehyde synthesised through the Reimer-Tiemann reaction significant in chemistry?

Student 3
Student 3

Is it used in perfumes or something?

Teacher
Teacher

Yes, it is used in perfumery; salicylaldehyde has a sweet scent. It’s also a precursor for various pharmaceuticals.

Student 2
Student 2

What types of pharmaceuticals?

Teacher
Teacher

Excellent question! Salicylaldehyde is used in the synthesis of anti-inflammatory medications and is involved in important biological mechanisms.

Student 1
Student 1

Can we also consider the environmental impact of these reactions in a practical context?

Teacher
Teacher

Absolutely! Considering the reagents and byproducts involved in reactions like the Reimer-Tiemann is essential for sustainable chemistry practices.

Teacher
Teacher

To recap, the Reimer-Tiemann reaction is not only a valuable synthetic pathway but also crucial for many applications in science and industry.

Introduction & Overview

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Quick Overview

The Reimer-Tiemann reaction involves the formation of salicylaldehyde from phenol using chloroform and sodium hydroxide.

Standard

The Reimer-Tiemann reaction is a chemical reaction where phenol is treated with chloroform in the presence of sodium hydroxide, resulting in the ortho-forming aldehyde salicylaldehyde. This two-step reaction introduces a –CHO group at the ortho position of the aromatic ring.

Detailed

Reimer-Tiemann Reaction

The Reimer-Tiemann reaction is an important organic reaction in which phenol is treated with chloroform in an alkaline environment, specifically using sodium hydroxide (NaOH). This reaction leads to the introduction of a formyl (–CHO) group at the ortho position of the phenolic ring, ultimately producing salicylaldehyde.

Mechanism and Steps

The reaction occurs in two major steps. First, the sodium hydroxide deprotonates phenol to form phenoxide ion, which then reacts with chloroform. This forms an intermediate compound called benzal chloride. Under hydrolytic conditions, this intermediate is converted into salicylaldehyde via hydrolysis.

This synthesis method is particularly significant because it provides a means to manufacture salicylaldehyde, which has applications in perfumery and the synthesis of pharmaceuticals. The ortho-selective nature of the reaction is notable because it illustrates how substituents on the aromatic ring can influence reaction outcomes through electrophilic substitution.

Importance

Understanding the Reimer-Tiemann reaction is crucial not only due to its practical utility in organic synthesis but also for its illustration of electrophilic aromatic substitution, the role of substituents in determining reaction pathways, and its applications in synthesizing biologically active compounds.

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Overview of Reimer-Tiemann Reaction

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On treating phenol with chloroform in the presence of sodium hydroxide, a –CHO group is introduced at the ortho position of the benzene ring. This reaction is known as Reimer - Tiemann reaction.

Detailed Explanation

The Reimer-Tiemann reaction is a chemical process where phenol (an aromatic compound with a hydroxyl group) reacts with chloroform in the presence of a strong base such as sodium hydroxide (NaOH). During this reaction, a formyl group (–CHO) is introduced at the ortho position relative to the hydroxyl group on the benzene ring. This means that the resulting compound has an aldehyde functional group adjacent to the –OH group. It’s important to note that this reaction specifically leads to the formation of salicylaldehyde, which is a compound with both an –OH and –CHO group attached to the benzene ring.

Examples & Analogies

Consider the Reimer-Tiemann reaction like modifying a letter in a text. You start with a letter 'O' (representing the hydroxyl group in phenol). Using a special pen (the chloroform and sodium hydroxide), you can add a new mark, like a decoration, right next to that letter. Now our letter becomes 'O' with a nice mark beside it, representing the new aldehyde group added to the phenol.

Mechanism of the Reaction

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The intermediate substituted benzal chloride is hydrolysed in the presence of alkali to produce salicylaldehyde.

Detailed Explanation

The mechanism of the Reimer-Tiemann reaction involves several steps. Initially, phenol interacts with chloroform and sodium hydroxide, resulting in the formation of an intermediate compound known as benzal chloride. This intermediate then undergoes hydrolysis, which is a reaction involving water that breaks it down into salicylaldehyde and hydrochloric acid. Hydrolysis helps to stabilize the final product, salicylaldehyde, by replacing the chlorine atom with a hydroxyl group. Therefore, the complete process transforms phenol into salicylaldehyde, which is useful in various applications including the fragrance and chemical industries.

Examples & Analogies

Think of the Reimer-Tiemann reaction like making a sandwich. First, you lay down the bread (phenol) and spread some butter (chloroform) on it. Then you add some special toppings (sodium hydroxide) that activate the mix. After some steps, like letting it sit with the right conditions (hydrolysis), you end up with a delicious meal (salicylaldehyde) ready to serve!

Definitions & Key Concepts

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Key Concepts

  • Reimer-Tiemann Reaction: A reaction that transforms phenol into salicylaldehyde.

  • Intermediate Product: Benzal chloride forms during the reaction.

  • Mechanism: The reaction proceeds through deprotonation, electrophilic attack, and hydrolysis.

Examples & Real-Life Applications

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Examples

  • The Reimer-Tiemann reaction illustrates how phenol can react to form salicylaldehyde, an important compound in organic synthesis.

Memory Aids

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🎵 Rhymes Time

  • In the Reimer's team, for salicylaldehyde, the chloroform and NaOH abide.

📖 Fascinating Stories

  • Once upon a time, in a lab, phenol wanted to don a new dress. With chloroform and NaOH, it transformed into salicylaldehyde, shiny and fresh.

🧠 Other Memory Gems

  • Remember: P-Phenol, C-Chloroform, Na-NaOH lead to S-Salicylaldehyde.

🎯 Super Acronyms

R-T-R for Reimer-Tiemann Reaction produces Salicylaldehyde.

Flash Cards

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Glossary of Terms

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  • Term: ReimerTiemann Reaction

    Definition:

    A chemical reaction where phenol reacts with chloroform in the presence of sodium hydroxide to produce salicylaldehyde.

  • Term: Salicylaldehyde

    Definition:

    An aromatic aldehyde derived from the Reimer-Tiemann reaction; significant in perfumery and pharmaceuticals.

  • Term: Phenol

    Definition:

    An aromatic compound that serves as a precursor for numerous applications and undergoes reactions to form other derivatives.

  • Term: Benzal Chloride

    Definition:

    An intermediate in the Reimer-Tiemann reaction formed from phenoxide ion reacting with chloroform.