Question

When alcoholic solution of ethylene dibromide is heated with granulated zinc, the compound formed is.
(a) Ethylene
(b) Ethyne
(c) Cyclobutane
(d) Butane

Answer 1

Hint: An elimination reaction involves the removal of two atoms that are connected to two neighbouring carbon atoms. The elimination reaction can be a one or two-step reaction.

Complete Step by Step Answer:
The given question involves the reaction of an alcoholic solution of ethylene dibromide with granulated zinc\[Zn\].

The structure of ethylene dibromide is composed of two bromine atoms which are linked with two neighbouring carbon atoms. The following image represents the exact structure of ethylene dibromide.

Image: Structure of ethylene dibromide.

When the granular zinc is heated with an alcoholic solution of ethylene dibromide, then the formation of ethylene occurs along with \[ZnB{r_2}\]salt.

Figure: Schematic presentation of ethylene synthesis.

In the above-mentioned reaction the granular zinc(\[Zn\]) acts as a de-halogenating reagent or in other world we can say granular zinc(\[Zn\]) cause the removal of bromine molecule from the ethylene dibromide.

Now we can say when a solution of ethylene dibromide is heated with granular zinc(\[Zn\]) the formation of alkene is observed, that is the formation of ethylene molecules occurs.
Therefore, from the above discussion, it is quite clear that option (a) will be the correct answer.

Note: The alkene and alkyne hydrocarbons represent the class of unsaturated hydrocarbons (compounds with carbon-carbon double and triple bonds). Whereas the alkane represents the class of saturated hydrocarbons (hydrocarbons with single carbon-carbon bonds). The unsaturated hydrocarbon is considered more reactive than the unsaturated hydrocarbon due to the presence of double and triple bonds.