Question

Which of the following compounds will give a yellow precipitate with iodine and alkali?
$A)$ Methyl acetate
$B)$ Acetamide
$C)$ $2 -$ Hydroxypropane
$D)$ Acetophenone

Answer 1

Ethanol is the solitary essential alcohol to give the triiodomethane response. Assuming " $R$ " is a hydrocarbon group, you have an optional Alcohol. Loads of optional alcohols give this response, yet those that do all have a methyl group appended to the carbon with the - OH group.To find the yellow precipitate, we must know the type of reaction which is taking place. The iodoform reaction is taking place.

Complete answer:
The formation of iodoform is responsible for formation of yellow precipitate. Iodoform $(C{H_3}I)$ is yellow in color and has a penetrating odour.
Iodoform is defined as a substance reaction in which a methyl ketone is oxidized to a carboxylate by reaction with aqueous $HO$ and ${I_2}$ . The reaction additionally delivers iodoform, a yellow strong which may hasten from the reaction blend. The iodoform response has been utilized as a substance test for the presence of a methyl ketone moiety.
${C_6}{H_5}COC{H_3} + NaOH + {I_2} \to {C_6}{H_5}C{O_2}Na + CH{I_3}$
Methyl acetate and acetamide will not undergo an iodoform test.
Correct options are $C)$ and $D)$ .

Note:
Iodoform, likewise called triiodomethane, a yellow, crystalline solid having a place with the group of natural halogen compounds, utilized as a clean part of prescriptions for minor skin infections. The haloform reaction is the reaction of a methyl ketone with chlorine, bromine, or iodine within the sight of hydroxide particles to give a carboxylate particle and a haloform. There is one aldehyde that goes through the haloform reaction, which is acetaldehyde.