Which solvent system should be used for the monitoring of biscoumarin synthesis for TLC. as it is dissolved in DCM for spotting and when it is runned in 6: 4 ratio of ethylacetate or hexane but it shows trails. so what should I do.
If you're seeing trailing, that generally means the what your initial spot is too concentrated. Try diluting your sample, spot the TLC and check under a UV lamp to make sure it doesn't appear too concentrated and then run the TLC. This is by far the most common reason for streaking, so diluting your sample will probably solve your problem.
If the coumarin derivatives you're making have certain functional groups (particually amines and carboxylate groups), these tend to streak regardless of what solvent system you use. In this case you might want to use a stronger eluting system (higher ratio of EA or use DCM/MeOH) which limits the amount of streaking you see.
Finally, you can try different a different solvent system. It doesn't necessarily need to be stronger eluting or more polar; rather, if you're observing streaking, it might be due to limited solubilty, which can be resolved with a solvent system that better dissolves your compound. For example, with coumarins, I might try using toluene as both toleune and coumarin are aromatic, so that the coumarin stays dissolved as the TLC is ran.
sir I dissolved it in DCM, either I should use other solvent or toluene is suitable.@Grant Simpson
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