Question

The $-OH$ of $-COOH$ group of a carboxylic acid can be replaced by $-Cl$ using:

• A. phosphorus pentachloride
• B. hypochlorous acid
• C. chlorine
• D. hydrochloric acid

Answer 1

The correct option is A phosphorus pentachloride

Carboxylic acids react with phosphorous trichloride $\left(PC{l}_3\right)$, phosphorous pentachloride $\left(PC{l}_5\right)$, thionyl chloride $\left(SOC{l}_2\right)$, and phosphorous tribromide $\left(PB{r}_3\right)$ to form acyl halides. Here $-OH$ of $-COOH$ group of a carboxylic acid can be replaced by $-Cl$. Hence option (a) is correct.