Question

The acidic strength of substituted carboxylic acid is known to depend on nature and position of substituents. In the following examples, an attempt has been made to arrange the acids in decreasing order of acidic strength. Which one of the series is incorrect?

• A. $O _{2} NCH _{2} COOH > HOCH _{2} COOH > CH _{3} COOH > CH _{2} BrCOOH$
• B. $Cl _{3} CCOOH > FCH _{2} COOH > Cl _{2} CHCOOH > CH _{2} BrCOOH$
• C. $CH _{3} CH _{2} CHClCOOH > CH _{3} CHClCH _{2} COOH > CH _{3} CH _{2} CH _{2} COOH > CH _{3} CH \left( CH _{3}\right) CH _{2} COOH$
• D. $CH _{3} COOH > CH _{3} CH _{2} COOH >\left( CH _{3}\right)_{2} CHCOOH > \left( CH _{3}\right)_{3} CCOOH$

Answer 1

Answer: (B)

Two $Cl$ from same positions gives greater $-I$ -effect than a single $F$ from the same position hence.

$Cl _{2} CHCOOH$ is stronger acid than $FCH _{2} COOH .$