The double bond is referred to as a chemical bond in which the two pairs of electrons are shared between the two atoms to form a bond among the elements. The double bond is formed when two atoms share two pairs of electrons. The Clemmensen Reduction includes the addition of Zn(Hg) which is dissolved in heated hydrochloric acid (HCl) to reducible form. Note that this process can accidentally chlorinate a double bond which is also present on the reactant side of the Clemmensen reduction reaction.