Question

Methyl iodide on reaction with sodium produces:
(a) Ethene
(b) Ethane
(c) Methane
(d) None of the above

Answer 1

Hint: Sodium is a soft metal which has a shiny and lustrous appearance. It gets tarnished on being exposed to air. it has the ability to get instantly oxidised by water and hydrogen gas in temporary union with a little amount of sodium being disengaged. It is a member of alkali metals which have low boiling and melting point.

Complete answer:
Wurtz reaction is the coupling reaction where the sodium metal is reacted with two alkyl halides in the environment provided by the dry ether which forms the higher alkane and the compound which contains sodium and a halogen. Wurtz reaction is a useful reaction in the field which includes organic chemistry and organometallic chemistry. The general chemical equation for the Wurtz reaction is the following:
\[R-X+2Na\to R-R+2NaX\]
So on reacting methyl iodide with sodium the products formed are the ethane and sodium iodide. The reaction for them is the following:
\[C{{H}_{3}}I+2Na\to C{{H}_{3}}-C{{H}_{3}}+2NaI\]
Here the two groups of R are joined to form a higher number of alkane and X is the halogen. By this reaction we can only form symmetric alkanes. We can not form methane by this reaction because we require the product which contains at least two carbon atoms.
So the correct option for this is option ‘(b) Ethane’.

Note: The Wurtz coupling reaction is not able to form products if tertiary alkyl halides are reacted. There exists a side reaction through which the formation of alkene takes place. The alkyl halide should be bulky especially at the end of halogen so that a great amount of alkene is formed at that end. It does not allow to form the product for dissimilar alkanes as it is difficult to separate that mixture.