Question

Which of the following compound is used as paint remover?

• A. Methylene chloride
• B. Iodoform
• C. Chloroform
• D. 2,4-dinitrophenylhydrazine

Hint:

Standard NCERT Industrial Uses:
\(\text{CH}_2\text{Cl}_2\): Paint remover, metal degreasing solvent.
\(\text{CHCl}_3\): Freon (R-22) manufacturing.
\(\text{CHI}_3\): Antiseptic powder.
\(\text{CCl}_4\): Fire extinguisher (Pyrene) and solvent.

Answer 1

The Correct Option is A

Concept:
Polyhalogen compounds are organic molecules that contain more than one halogen atom per molecule.
Many polyhalogen derivatives of methane and ethane possess unique solvency properties, moderate boiling points, and volatility, making them industrially valuable as solvents, degreasers, propellants, and strippers.

Step 1: Chemical Nature of Methylene Chloride:
Methylene chloride is the common name for dichloromethane, having the chemical formula \(\text{CH}_2\text{Cl}_2\).
It is a colorless, volatile chlorinated hydrocarbon liquid with a moderately sweet aroma and high dissolving power for synthetic resins, varnishes, and polymers.

Step 2: Industrial Application as a Paint Remover:
Due to its high chemical stability, non-flammability under standard conditions, and ability to penetrate and swell cross-linked paint films, methylene chloride is extensively utilized as the primary active solvent in commercial paint strippers and paint removers.
It rapidly breaks the adhesion between the paint film and the underlying substrate, allowing old coatings to be scraped away easily.
It is also utilized as a process solvent in the pharmaceutical industry and as an aerosol propellant.

Step 3: Evaluating Alternative Reagents:
Iodoform (\(\text{CHI}_3\)) was historically employed as an antiseptic because of the gradual liberation of elemental iodine, not as an industrial solvent.
Chloroform (\(\text{CHCl}_3\)) was historically an anesthetic and is currently used in the synthesis of R-22 refrigerant.
2,4-Dinitrophenylhydrazine is an analytical reagent (Brady's reagent) utilized solely for detecting carbonyl functionalities in aldehydes and ketones.
Final Answer:
Therefore, the compound used commercially as a paint remover is methylene chloride, corresponding to option (A).