Question

Question #afbd8

Answer 1

Propanone and propanal show keto-enol tautomerism.

Explanation:

A compound must have a carbonyl (`"C=O"`) group and an α- hydrogen.

Methoxypropane

The structures of the two isomeric methoxypropanes are

`underbrace("CH"_3"CH"_2"CH"_2"-OCH"_3)_color(red)("1-methoxypropane")` and `underbrace("CH"_3"CH"("OCH"_3)"CH"_3)_color(red)("2-methoxypropane")`

Neither has a carbonyl group, so neither shows keto-enol tautomerism.

Propanone

Propanone has a carbonyl group and six α-hydrogens, so it shows keto-enol tautomerism.

`underbrace("CH"_3"(C=O)CH"_3)_color(red)("keto form") ⇌ underbrace("CH"_3"C(OH)=CH"_2)_color(red)("enol form")`

Propanal

Propanal has a carbonyl group and two α-hydrogens, so it shows keto-enol tautomerism.

`underbrace("CH"_3"CH"_2"(C=O)H")_color(red)("keto form") ⇌ underbrace("CH"_3"CH=CHOH")_color(red)("enol form")`

Pentan-2-ol

The structure of pentan-2-ol is `"CH"_3"CH"_2"CH"_2"CH(OH)CH"_3`.

Pentan-2-ol has no carbonyl group, so it does not show keto-enol tautomerism.