Hello all,

I'm doing a research product on the efficacy of different lewis-acids to catalyze diels-alder reactions. I want to measure the rate of product formation through UV-Vis sprectoscopy, but I need a reaction in which the product of the reaction is colored, while the products are not. I've been scouring Google Scholars to no avail :/

Any ideas for substrates?

Why does it need to be coloured? UV-Vis works outside the visible spectrum as well. Unless there's some other reason for needing the products to be coloured, all you really need is something you can easily make and that absorbs differently to the starting material. A quick search of "Diels Alder reaction rates UV-Vis" in Google provides a few examples you could try, but some of these may be precluded depending on what context you're doing it in. For instance, it is unlikely that you would be able to play with anything especially toxic or potentially explosive if you were doing this for an undergrad course.

Edit: alternatively (and this may be easier), you could look for a reaction where the diene absorbs in the UV or visible region, where the product does not (or at least, does not absorb in the same region).

"I need a reaction in which the product of the reaction is colored, while the products are not"

Bad luck.

 

A characteristic of D-A reactions is that they remove a conjugated double bond.

That's almost bound to mean a shift in the absorbance to shorter wavelength