Preparation of BenzeneBenzene and its homologues may be prepared by the following methods.
By the decarboxylation of sodium benzoate
This method is used in the laboratory to obtain benzene. Sodium benzoate is heated with soda-lime and when it gets decarboxylated (removal of carbon dioxide) benzene is obtained.
sodium benzoate sodalime Benzene
By heating phenol with zinc
When phenol vapours are passed over heated zinc dust, benzene is formed.
By the polymerization of ethyne (acetylene)
When ethyne (acetylene) is passed through a red hot copper tube, it polymerises to benzene.
By the reduction of benzene diazonium chloride
Benzene is formed on the reduction of benzene diazonium chloride with sodium stannite or hypophosphorus acid.
C6H5NCl- + H3PO2 + H2OC6H6 + N2 + H3PO3 + HClbenzenediazoniumchloride
By the hydrolysis of sulphonic acid
Benzene sulphonic acid on hydrolysis with superheated steam gives benzene.
C6H5.SO3H + H2O C6H6 + H2SO4
benzene sulphonic acid benzene