Which of the following is not a practical method for synthesizing alkynes ?

Options

A. Dehydrohalogenation of gem-dihalides
B. Dehydrohalogenation of vic-dihalides
C. dehalogenation of tetrahalides
D. none of these

Answer

C

Explanation

The required tetrahalide is usually prepared by adding two equivalents of `X_2` to an alkyne:
`C-=C+2X_(2)to-underset(X)underset(|)overset(X)overset(|)(C)-underset(X)underset(|)overset(X)overset(|)(C)-overset(-2X_(2))to-C-=C-`
However, this reaction is used to protect, i.e., to prevent the unwanted reaction of triple bond in a polyfunctional alkyne that is about to undergo a reaction which would also destry the `-C-=C-`. For this purpose, `X_2` is first added to the alkyne to give the tetrahalo derivative. The desired reaction is carried out without affecting the tetrahalide. Finally the alkyne is regenerated by a double dehalogenation with Zn.