Which of the following reducing agents causes the reduction of an alkyl halide by means of nascent hydrogen?

Options

A. `Zn and CH_(3)COOH`
B. `Zn and dil HCl`
C. `Zn-Cu` couple and `C_(2)H_(5)OH`
D. `Zn` and `NaOH`

Answer

D

Explanation

With `Zn` and an acid or with `Zn-Cu` couple and `C_(2)H_(5)OH`, the reduction occurs by the transfer of electrons from `Zn` atoms to the `C` atom of the alkyl halide. The reaction takes place in a separate phase at or near the surface of the `Zn` metal:

An alkylzinc halide forms first and then reacts with the acid to produce the alkane.
With `Zn//NaOH`, reduction occurs with nescent hydrogen:
`Zn+2NaOHrarrunderset("Sodiumzincate")(Na_(2)ZnO_(2))+2[H]`
`RX+2[H]rarrR-H+HX`