Propionic acid with `Br_(2)`/`P` yields a dibromo product. Its structure would be

Options

A. `CH_2Br-CHBr-COOH`
B. `H-undersetunderset(Br)(|)oversetoverset(Br)(|)C-CH_2COOH`
C. `CH_2Br-CH_2-COBr`
D. `CH_3-undersetunderset(Br)(|)oversetoverset(Br)(|)C-COOH`

Answer

D

Explanation

`underset("Propionic aicd")(CH_3-undersetunderset(H)(|)oversetoverset(H)(|)C-COOH)underset(-2HBr)overset(Br_2//P)to CH_3-undersetunderset(Br)(|)oversetoverset(Br)(|)C-COOH`
Carbonylic acids reacts with `Cl_2` or `Br_2` in presence of red P to give exclusively `alpha`-chloro or `alpha` -bromo acids. This reaction is called Hell-Volhard-Zelinsky (HVZ) reduction . This reaction is example of `alpha` H-substitution.