I'm inquiring about a question regarding column chromatography. I would like some advice, or guidance, on how I should proceed. I am in the process of synthesizing a novel compound, and during the purification process, I always obtain mixed fractions.
Attached includes the TLC plate I obtained, as well as the reaction scheme. In regards to the TLC chamber eluent, I used 8:1 DCM/MeOH.
For my column, I typically go 200:1 (100 mL of DCM and 0.5 mL of MeOH) DCM/MeOH. In regards to how I prepare my column, I typically, add cotton, then my slurry. Afterwards, I dry-load my compound. In my column, I usually add 1% Et3N, and while preparing my dry-load, I also add Et3N.
The way I potentially wash might be an issue? The solvent is DMF. Once the reaction is over, I dilute with DCM (2x), then wash with water (2x), then brine.
The column is 250 mL, and fairly long and skinny. To clarify, the attachment was for 500 mg.
I am currently rerunning the reaction, and my theoretical yield is 1 gram. Any advice would be greatly appreciated.
The flow-rate is also not that fast. I am just confused on why I keep obtaining mixed fractions in my column. How can I prevent getting two fractions?
Could it be that my eluent for my column is too polar? When running the TLC, I can't get any movement using hexane/EA