[Radcat]

diels-alder reaction Why does the initial yellow color of the reaction mixture fade during the reaction?

[Mitch]

you are going to have to be way more specific. There are literally thousands of different diels-alder reactions.

[Radcat]

maleic anhydride + anthracene <> 9,10-dihydroanthracene-9,10-alpha, beta-succinic acic anhydride

[cardshark3500]

the number of conjugated double bonds are being reduced as the reaction takes place. Since molocules with more conjugated bonds have visible colors, the reduction of these bonds will eventually yield a color that is not visible to the human eye.