Question

$C{H_3} - CH = C{H_2} + C{l_2}\xrightarrow{{773K - 873K}}$

Answer 1

Hint : The reactant present here is an alkene, undergoing reaction with the chlorine at a very high temperature. It is the process of alkene undergoing allylic substitution at a very high temperature in the gas phase.

Complete Step By Step Answer:
The allylic position is the one which is intermediately adjacent to the double bond. The allylic position represents characteristic chemical properties. Some allylic species are specially stabilized due to adjacent double bonds.
The specific characteristic of allylic systems is reflected in their chemical reactions. Generally at room temperature chlorine and bromine are added to the double bonds of alkenes. At higher temperature, the addition reaction is increasingly superseded by the allylic substitution, especially when the halogen concentration is low.
Substitution reaction which is also known as the single displacement reaction is a chemical reaction during which one functional group in a chemical compound is replaced by another functional group. Substitution reactions are either electrophilic or nucleophilic. It depends upon the reagent involved whether it is carbocation, carbanion or a free radical and whether the substrate is aliphatic or aromatic.
When at high temperature allylic substitution is taking place chlorine molecules are homolytically cleaved by thermal energy into two chlorine radicals. They then undergo the allylic substitution without breaking the double bond. Chlorine replaces the hydrogen of alpha carbon atom and form the following product-
$C{H_3} - CH = C{H_2} + C{l_2} \to ClC{H_2} - CH = C{H_2}$

Note :
Nucleophilic and electrophilic substitution differ in the kind of atom which is attached to its original molecule. In the nucleophilic reaction the atom is said to be electron rich species, whereas in the electrophilic reaction the atom is an electron deficient species.