Question

What is Wurtz reaction? What are its limitations? How have these limitations been overcome?

Answer 1

Wurtz's reaction is an organic chemical coupling reaction in which sodium metal reacts with two alkyl halides in the presence of a dry ether solution to produce a higher alkane and a molecule containing sodium and the halogen.

Complete answer:
This reaction uses free radicals as a catalyst, which allows for side reactions that result in the synthesis of alkenes as a byproduct. The Wurtz-Fittig reaction, which is similar to the Wurtz Reaction but uses aryl halides instead of alkyl halides, is a very important named reaction in organic chemistry.
Equation of Wurtz Reaction
The Wurtz reaction equation can be expressed in its general form as follows:
$2R - X + 2Na \to R - R + 2N{a^ + }{X^ - }$
The two $R$ groups are united in this equation, resulting in an alkane with a longer chain as well as $NaX$ where $\;X$ is a Halogen.
The Wurtz Reaction's Limitations
This reaction has a few drawbacks, which are outlined below.
Because a variety of alkane products is generated when different alkanes are reacted, this approach is often used to synthesize symmetric alkanes (these mixtures are difficult to separate).
There is a side reaction that produces an alkene product. There is a greater amount of alkene produced if the alkyl halides are bulky in character, especially at the halogen end.
Because the result of an organic coupling reaction must include at least two carbon atoms, methane cannot be produced using the Wurtz process.
When tertiary alkyl halides are utilised, the Wurtz coupling process usually fails.

Note:
In addition, because the reaction involves free radical species, an alkene is produced as a byproduct. When the alkyl halides are bulky at the halogen-attached carbon, this side-reaction becomes more prominent. The alternate elimination method is preferred because the activation energy required for the $SN2$ reaction in the second phase becomes much higher. As a result, only primary alkyl halides should be used in the synthesis. Otherwise, employ a reagent with sodium metal linked to the tertiary or secondary carbon.