Question: Rank the following dienophiles in order of increasing reactivity

In a Diels-alder reaction, a compound that reacts readily with a diene like an alkene is called dienophile.

Examples of good dienophiles are ketone, nitro, nitrile, aldehyde, etc. The best dienophile is maleic anhydride.

A dienophile that has an electron-withdrawing group attached to one or both carbons is called a good dienophile.

Structural formula of acrylic acid

As it has one electron-withdrawing group, the reactivity will be intermediate.

Structural formula of maleic acid

As it has two electron-withdrawing groups, the reactivity will be more. ${\mathrm{H}}_2\mathrm{C}=\mathrm{CH}-{\mathrm{CH}}_3$

As it does not have an electron-withdrawing group, the reactivity will be very less.

So the dienophile can be ranked in the increasing order based on this information.

Reactivity of dienophile in the increasing order