The preparation of 2,4-dichloronitrobenzene from nitrobenzene and chlorine gas can be carried out through electrophilic substitution reaction. Here is the step-by-step procedure:1. Set up a reaction apparatus consisting of a round-bottom flask, a dropping funnel, a condenser, and a gas inlet tube for the introduction of chlorine gas.2. Add nitrobenzene to the round-bottom flask and cool it to 0-5C using an ice bath. This is done to control the reaction rate and minimize the formation of undesired by-products.3. Slowly introduce chlorine gas into the reaction mixture through the gas inlet tube. The electrophilic substitution reaction will occur, and the nitrobenzene will be chlorinated at the 2 and 4 positions to form 2,4-dichloronitrobenzene.4. Monitor the reaction progress using thin-layer chromatography TLC or another suitable analytical technique. The reaction is complete when no starting material nitrobenzene is detected.5. Once the reaction is complete, separate the 2,4-dichloronitrobenzene from the reaction mixture by filtration or extraction, followed by washing with water to remove any remaining inorganic salts.6. Purify the crude product by recrystallization from a suitable solvent, such as ethanol or ethyl acetate, to obtain pure 2,4-dichloronitrobenzene.Physical and chemical properties of 2,4-dichloronitrobenzene:- Molecular formula: C6H3Cl2NO2- Molecular weight: 202.00 g/mol- Appearance: Yellow to light brown crystalline solid- Melting point: 47-51C- Boiling point: 315C- Density: 1.58 g/cm- Solubility: Slightly soluble in water, soluble in organic solvents like ethanol, acetone, and diethyl ether.- Reactivity: 2,4-dichloronitrobenzene can undergo further electrophilic substitution reactions, reduction reactions to form 2,4-dichloroaniline, and nucleophilic aromatic substitution reactions.Remember to follow safety precautions and wear appropriate personal protective equipment PPE when carrying out this reaction, as both nitrobenzene and chlorine gas are hazardous chemicals.