Difference Between Wurtz and Wurtz-Fittig Reaction (Table)
Wurtz-Fittig Reaction is essential in chemistry and helps students understand various practical and theoretical applications related to this topic.
What is Wurtz-Fittig Reaction in Chemistry?
A Wurtz-Fittig Reaction refers to an organic coupling process where an aryl halide reacts with an alkyl halide in the presence of metallic sodium and dry ether to produce an alkyl-substituted aromatic compound.
This concept appears in chapters related to haloalkanes and haloarenes, coupling reactions, and aromatic hydrocarbons, making it a foundational part of your chemistry syllabus.
Molecular Formula and Composition
The general formula for the Wurtz-Fittig Reaction can be represented as Ar-X + R-X + 2Na → Ar-R + 2NaX, where Ar-X is an aryl halide and R-X is an alkyl halide. The product, Ar-R, is an alkylbenzene or substituted aromatic hydrocarbon and is categorized under aromatic compounds.
Preparation and Synthesis Methods
The Wurtz-Fittig Reaction is generally performed in the laboratory. An aryl halide (like bromobenzene) and an alkyl halide (like ethyl bromide) are mixed with small pieces of sodium metal in anhydrous (dry) ether. The mixture is stirred, allowing sodium to facilitate the coupling. This reaction is not widely used in industry due to formation of side products, but it is important for academic and preparative chemistry.
Step-by-Step Reaction Example
- Start with the reaction setup.
Bromobenzene (C6H5Br) and ethyl bromide (C2H5Br) are dissolved in dry ether. - Add sodium metal.
Sodium pieces are added to the solution under stirring. - Reaction occurs with sodium coupling.
C6H5Br + C2H5Br + 2Na → C6H5C2H5 (ethylbenzene) + 2NaBr - Explain each intermediate or by-product.
Small amounts of biphenyl (from aryl halide only) and butane (from alkyl halide only) may also be formed.
Chemical Properties and Reactions
The Wurtz-Fittig Reaction proceeds either via a free radical or an ionic (organo-alkali) mechanism. Sodium donates an electron to both halides, generating radicals. These radicals couple to yield the main aryl-alkyl product, while also leading to side products if radicals combine with their own kind.
The reaction is influenced by the reactivity of the halides, with alkyl halides usually reacting faster due to higher reactivity compared to aryl halides.
Frequent Related Errors
- Confusing Wurtz-Fittig Reaction with Wurtz or Fittig reactions due to similarity in reagents.
- Mixing up the structures of the main product and the side products.
- Forgetting that dry ether is essential as sodium reacts violently with water.
- Assuming the reaction is suitable for tertiary alkyl halides (it usually gives elimination products instead).
Uses of Wurtz-Fittig Reaction in Real Life
Wurtz-Fittig Reaction is mostly used for laboratory synthesis of substituted aromatic compounds and sometimes for organosilicon compounds. It highlights the method of forming carbon–carbon bonds in aromatic chemistry, useful for understanding complex molecule construction.
Relation with Other Chemistry Concepts
Wurtz-Fittig Reaction is closely related to coupling reactions such as the Wurtz Reaction (which uses two alkyl halides) and the Fittig Reaction (using two aryl halides). It builds a conceptual bridge to Friedel-Crafts Alkylation and helps in understanding the ways carbon frameworks are expanded in organic synthesis.
Lab or Experimental Tips
Remember, sodium must always be handled in dry conditions and cut freshly for best activity. If moisture is present, sodium will react fiercely with water, making the reaction unsafe and unproductive. Vedantu educators often use the “dry ether = dry products” cue in live classes to remind students of this rule.
Try This Yourself
- Write the equation for the Wurtz-Fittig reaction between chlorobenzene and propyl bromide.
- Compare the main difference between Wurtz, Fittig, and Wurtz-Fittig reactions in a table.
- Predict the main product when bromoethane and bromobenzene react with sodium in dry ether.
Final Wrap-Up
We explored the Wurtz-Fittig Reaction—its definition, examples, mechanism, errors to avoid, and its relation to other organic reactions. For more explanations and interactive concept lessons, check Vedantu’s live chemistry sessions and detailed notes.
| Reaction | Type of Compounds Used | Product Formed |
|---|---|---|
| Wurtz Reaction | Two alkyl halides | Higher alkane |
| Fittig Reaction | Two aryl halides | Biaryl compound |
| Wurtz-Fittig Reaction | One aryl + one alkyl halide | Alkyl-substituted aromatic |
Wurtz Reaction
Haloalkanes and Haloarenes
FAQs on Wurtz-Fittig Reaction – Mechanism, Equation, and Applications
1. What is the Wurtz-Fittig reaction in Chemistry?
The Wurtz-Fittig reaction is an organic coupling process in which an aryl halide reacts with an alkyl halide in the presence of sodium metal and dry ether to produce an alkylbenzene. This reaction is commonly used to synthesize substituted aromatic hydrocarbons such as toluene.
2. Give one example of the Wurtz-Fittig reaction.
An example of the Wurtz-Fittig reaction:
Bromobenzene + chloromethane + sodium (dry ether) → toluene + sodium bromide + sodium chloride
The equation:
C6H5Br + CH3Cl + 2Na → C6H5CH3 + NaBr + NaCl
3. What is the difference between Wurtz and Wurtz-Fittig reactions?
Wurtz Reaction:
- Involves two alkyl halides
- Produces alkanes
Wurtz-Fittig Reaction:
- Involves one aryl halide and one alkyl halide
- Produces alkylbenzenes
A key difference is that Wurtz reaction cannot be used to synthesize aromatic compounds, while Wurtz-Fittig specifically enables the formation of alkyl-substituted benzene derivatives.
4. What type of reaction mechanism does the Wurtz-Fittig reaction follow?
The Wurtz-Fittig reaction mainly follows a free radical mechanism:
- Sodium donates electrons to halides to form radicals
- Radicals couple to form the final alkylbenzene
- Ionic mechanisms may also play a minor role, but the free radical pathway is predominant
5. What conditions are essential for the Wurtz-Fittig reaction to proceed?
The Wurtz-Fittig reaction requires:
- An aryl halide (e.g., bromobenzene)
- An alkyl halide (e.g., chloromethane)
- Metallic sodium
- Anhydrous dry ether as solvent
Proper dryness is essential to prevent sodium from reacting with water.
6. Why does the Wurtz-Fittig reaction use sodium in dry ether?
Sodium acts as a reducing agent, generating free radicals for coupling, while dry ether:
- Solubilizes the reactants
- Prevents sodium from decomposing in the presence of water
- Provides an inert medium for the reaction
7. What types of products are formed in the Wurtz-Fittig reaction?
The main product is an alkyl-substituted benzene (e.g., toluene or ethylbenzene).
Side products may include:
- Biphenyl (if two aryl radicals couple)
- Alkanes (if two alkyl radicals couple)
- Unreacted starting materials
8. What are the practical limitations of the Wurtz-Fittig reaction?
Limitations include:
- Polyalkylation or side reactions (undesired coupling)
- Low reactivity of some aryl halides
- Formation of mixture of products
- Not suitable for alkyl halides containing sensitive groups
9. How does the Wurtz-Fittig reaction differ from the Fittig reaction?
Fittig Reaction: Couples two aryl halides to form biphenyl.
Wurtz-Fittig Reaction: Couples one aryl halide with one alkyl halide to form an alkylbenzene.
Thus, the key difference is the type of halides involved and the product formed.
10. What are some important applications of the Wurtz-Fittig reaction?
The Wurtz-Fittig reaction is used for:
- Synthesis of alkylbenzenes like toluene and ethylbenzene
- Preparation of intermediates in perfumery and pharmaceutical compounds
- Academic demonstrations of organic coupling reactions
11. Can phenol or other functional group compounds participate in the Wurtz-Fittig reaction?
No, phenol and most functionalized aromatic compounds do not participate directly because the reaction specifically requires aryl halides (not phenols or other groups) for effective coupling with alkyl halides.
12. Is Wurtz-Fittig reaction SN1 or SN2?
The Wurtz-Fittig reaction does not follow a typical SN1 or SN2 mechanism. Instead, it primarily proceeds via a free radical pathway involving sodium-mediated coupling of radicals.
