Question

Observe the following reaction:
$CH_3(CH_2)_{11}C_6H_5 \xrightarrow[(ii) NaOH(aq)]{(i) H_2SO_4} X$
Which of the statements is not correct regarding X?

• A. It is an anionic detergent
• B. It is used in tooth pastes
• C. It is a cationic detergent
• D. Its anionic part is involved in cleansing action

Hint:

{Anionic:} Sulfonates/Sulfates (Cleaning agents, toothpaste). {Cationic:} Quaternary Ammonium salts (Hair conditioners, Germicides). {Non-ionic:} Esters (Dishwashing liquids).

Answer 1

The Correct Option is C

Step 1: Identify the Reaction Product X:
Reactant: Dodecylbenzene (Laurylbenzene). Reagents: Sulfonation ($H_2SO_4$) followed by Neutralization ($NaOH$). Product X: Sodium Dodecylbenzenesulfonate (SDBS). Structure: $CH_3(CH_2)_{11}-C_6H_4-SO_3^- Na^+$.
Step 2: Classify the Detergent:
The large hydrocarbon part is attached to the anion ($SO_3^-$). Therefore, it is an Anionic Detergent.
Step 3: Evaluate Statements:
(A) It is an anionic detergent - Correct. (B) It is used in toothpastes - Correct (Anionic detergents like Sodium Lauryl Sulfate/Sulfonates are used). (C) It is a cationic detergent - Incorrect. (Cationic detergents are usually quaternary ammonium salts). (D) Its anionic part is involved in cleansing - Correct.
Step 4: Final Answer:
The incorrect statement is (C).