Write the reaction equations: ethylene → dichloroethane → acetylene → benzene → cyclohexane → hexane → propane.

Let us write down the reaction equations for the transformation chain:
Н2С = СН2 + Сl2 = H2C – Cl – CH2 – Cl – halogenation reaction, dichloroethane is released;
Н2СCl – CH2Cl + 2KOH = CH2OH – CH2OH + 2KCl – exchange, ethylene glycol was obtained;
CH2OH – CH2OH = 2H2O + C2H4 – dehydration, ethylene was formed;
C2H4 = H2 + C2H2 – dehydrogenation, obtained acetylene;
3C2H2 = C6H6 – trimerization, benzene is released:
C6H6 + 3H2 = C6H12 – hydrogenation, obtained cyclohexane;
C6H12 + H2 = C6H14 – addition, hexane was formed;
С6Н14 = С3Н8 + С3Н6 – thermal cracking, propane was obtained.
The solution process shows the relationship between different classes of hydrocarbons: alkenes, alkynes, aromatic hydrocarbons and alkanes.