When doing the TLC how do you know the one on the right is the product? The RF is almost the same for the one on the left, but because left is way more concentrated, it had caused streaking.
Thanks for the comments, Mairis! Well, for this particular reaction the RF is almost the same. We have characterized the spot (compound) thoroughly using NMR and Mass spectroscopy techniques.
Dilute your sample. Switch solvents. 1-Chlorobutane is a great alternative to hexane. Similar to 15-25% EtOAc:Hex, but it has a tendency to separate things EtOAc:Hex, will not. Also, it flips the spots, sometimes. This makes it easier, if one wants the now top spot, that was bottom in EtOAc:Hex. Just cause its a new spot, doesn't mean it is the desired product.
In this type of case another eluent system including a protic polar phase like 99:1 - 95:5 DCM/MeOH is useful to remove the streaking by favoring H-bonding of the starting material with the eluent. If you have two spots at the same height, you can also reveal with various stains. Some might be selective of your starting material and allow for proper monitoring. A good start for stains screening can be p-anisaldehyde, CAN, nihnydrin, I2 and KMnO4. If none of them are selective of your starting material, you can still do a MS without forgetting to record a spectra of the starting material as a reference. PS: TLC are better run with a co-spot. Thanks to Tretyakova lab for the content.
Желаю успехов!
Thank you ❤️
Cool!!!
Thank you for the video. Please teach me how long it takes to purge the flask with gas using the balloon? I need to use argon in our lab too.
When doing the TLC how do you know the one on the right is the product? The RF is almost the same for the one on the left, but because left is way more concentrated, it had caused streaking.
Thanks for the comments, Mairis! Well, for this particular reaction the RF is almost the same. We have characterized the spot (compound) thoroughly using NMR and Mass spectroscopy techniques.
Dilute your sample. Switch solvents. 1-Chlorobutane is a great alternative to hexane. Similar to 15-25% EtOAc:Hex, but it has a tendency to separate things EtOAc:Hex, will not. Also, it flips the spots, sometimes. This makes it easier, if one wants the now top spot, that was bottom in EtOAc:Hex. Just cause its a new spot, doesn't mean it is the desired product.
In this type of case another eluent system including a protic polar phase like 99:1 - 95:5 DCM/MeOH is useful to remove the streaking by favoring H-bonding of the starting material with the eluent. If you have two spots at the same height, you can also reveal with various stains. Some might be selective of your starting material and allow for proper monitoring. A good start for stains screening can be p-anisaldehyde, CAN, nihnydrin, I2 and KMnO4. If none of them are selective of your starting material, you can still do a MS without forgetting to record a spectra of the starting material as a reference. PS: TLC are better run with a co-spot. Thanks to Tretyakova lab for the content.
Concentration is toooo high on left, reduce concentration, try different combinations of solvent
imagine being a doctor and still thinking its called mass spectroscopy