Question

What is vicinal dihalide \[?\]

Answer 1

Hint: First we know vicinal dihalides are hydrocarbon containing dihalides on adjacent carbons of a hydrocarbon. but geminal dihalides are halides in which dihalides are attached to the same carbon atom.
In chemistry, the term vicinal refers to the relationship between two functional groups that are attached to adjacent atoms. The descriptor geminal refers to the relationship between two atoms or functional groups that are attached to the same atom.

Complete answer:
Vicinal dihalides are compounds that have halogens on adjacent carbons, and are prepared by the reaction between a halogen and an alkene. Simply, dihalides in which two halogen atoms are attached to two adjacent carbon atoms are known as vicinal dihalides. The simplest example is the reaction between ethylene and chlorine to give 1,2-dichloroethane (ethylene dichloride). 1,2-Dichloroethane leads all other organo-halogen compounds.
Vicinal dihalides on treatment with zinc metal lose a molecule of \[Zn{X_2}\] to form an alkene. This reaction is known as dehalogenation. Its chemical reaction is generally written as
 \[2C{H_2}X + Zn \to 2C{H_2} + Zn{X_2}\]
Where \[X\] is any one of the halogen elements. Hence, dehydrohalogenation is an elimination reaction that eliminates (removes) a hydrogen halide from a substrate.

Note:
Note that Halogen elements are very reactive. The halogen elements have seven valence electrons in their outermost electron shell. Therefore, these elements can receive an electron from another atom and form very stable compounds. Also note that halogens' outermost shell is full.