What is WurtzFittig reaction?

In an extended approach made by Wilhelm Rudolph Fittig on the Wurtz Reaction that is given by Charles Adolphe, we obtained what is known as the WurtzFittig reaction. This particular reaction is given a name after Charles Adolphe Wurtz and Wilhelm Rudolph Fittig and is considered to be a modification of the Wurtz – Reaction. It is an organic reaction thatis considered to be one of the most important reactions in organic chemistry as a whole which helps in the synthetization of C – C bonds.

About the WurtzFittig reaction

TheWurtzFittig reactionis a reaction taking place in the presence of dry ether. This reaction takes place between a sodium metal, an alkyl halide with aryl leading to the formation of substituted aromatic compounds. This reaction forms a new carbon-carbon bond. The particular reaction is given as under:

R-X+2Na+Ph-X  Ph-R + 2NaX

This reaction is one of the best reactions which is used mainly for the preparation of products that are asymmetrical in cases where there is a difference between the relative chemical activities of the halide reactants. The WurtzFittig reaction is widely used for the alkylation of aryl halides. The reaction can also be used for biphenyl compounds production with the help of ultrasound.

This is reaction is a coupling reaction which is a modified version of the knownWurtz reaction. Let’s, look abit at the Wurtz reaction. It is also known to be a coupling reaction in a branch of Chemistry called organometallic chemistry. This reaction occurs in the presence of dry ether where there is an interaction between two alkyl halides and sodium metal leading to the formation of a higher alkane by forming a new C – C bond. Wurtz Reaction is given as under:

2R – X + 2Na  R – R + 2NaX

Where R is an alkyl group and

X is a halide ion

Mechanism of Wurtz – Fittig Reaction

The Mechanism involved in theWurtz – Fittig reaction is still not yet certain so far because two available approaches describe best the mechanism involved in theWurtz – Fittig reaction with available empirical evidence for both the approaches. These approaches are discussed below:

1. Radical mechanism
2. Organo – alkali mechanism
3. Radical Mechanism

The radical approach mainly focuses on the formation of the alkyl radical and sodium-mediated aryl radical. In this mechanism, the mediator in the reaction is sodium metal which helps in thearyl radical and alkyl radical formation.  In the next step, there is a combination between the alkyl radical and aryl radical which leads to the formation of a substituted aromatic compound. The difference between this mechanism and the organo- alkali mechanism is that the latter cannot explain the formation of side productsthat supports the Radical mechanism. Let’s consider an example, in a reaction of sodium and chlorobenzene as found by Bachmann and Clarke, there are many side products and one of them is triphenylene. This formation of triphenylene can only be explained by the radical mechanism.

2. Organo – Alkali Mechanism

Another approach i.e., the organo – alkali approach however discussesan intermediate formation of an organo – alkali compound in the reaction between an aryl halide and the sodium metal. In this mechanism, the aryl halide firstly reacts with the sodium metal forming the organo-alkali compound followed by the nucleophilic attack of alkyl halide. However, indirect evidence supported this mechanismwhere there is an observation by many investigators that an organo – alkali formation takes place during the reaction.

Metals other than Sodium metal

Other metals such as copper, potassium, iron, lithium, and so on can also be used to carry out the Wurtz – Fittig reactions. If in case lithium is used in place of sodium, there is more yield however the reaction will take place only under the effect of ultrasound. The use of lithium takes place by the free radical mechanism.

Wurtz Reaction, Wurtz – Fittig Reaction, and Fittig Reaction

There has been a lot of confusion amongst students between theWurtz reaction, Wurtz – Fittig reaction, and the Fittig reaction. Here a comparative study of the above three reactions is given in the tabular form

This is a brief introduction of theWurtz – Fittig reaction, to learnmore concepts, refer: haloalkanes and haloarenes from class 12 chemistry – find all the questions & answers