Ethylene, also known as ethene, is a hydrocarbon with the chemical formula C2H4. It is an unsaturated hydrocarbon because it contains a double bond between the two carbon atoms.

HBr, on the other hand, is hydrogen bromide, a strong acid composed of hydrogen and bromine. When ethylene reacts with HBr, a substitution reaction takes place, where the hydrogen atom from HBr replaces one of the carbon atoms in the double bond of ethylene.



The reaction between ethylene and HBr leads to the formation of ethyl bromide, also known as bromoethane. The chemical equation for this reaction is as follows:

C2H4 + HBr → C2H5Br

Ethyl bromide (C2H5Br) is an alkyl halide, which is a compound that contains a halogen atom (in this case, bromine) bonded to a carbon atom. It is a colorless liquid with a sweet odor.



The reaction between ethylene and HBr involves the breaking of the double bond in ethylene and the addition of HBr to the resulting carbocation intermediate. Here is a step-by-step explanation of the reaction:

1. The double bond in ethylene is a region of high electron density. It attracts the positively charged hydrogen atom in HBr, leading to the formation of a carbocation intermediate.

2. The carbocation intermediate is a positively charged carbon atom. It is highly reactive and can easily bond with the negatively charged bromine atom in HBr.

3. The bromine atom forms a bond with the carbocation, resulting in the formation of ethyl bromide. The positive charge on the carbon atom is neutralized by the addition of the bromine atom.



In summary, the reaction between ethylene and HBr results in the formation of ethyl bromide. This reaction involves the breaking of the double bond in ethylene and the addition of HBr to the resulting carbocation intermediate. Ethyl bromide is an alkyl halide and is formed as a result of the substitution reaction between ethylene and HBr.

CH2=CH2. + HBr. ---------. CH3-- CH2--Br