Nežinau, kokia procedūra jis vis giriasi, bet šiuo metu geriausius rezultatus pasiekiau ketoną ištirpindamas šiek tiek dcm, šiek tiek pašildęs iki 35-40, iš karto įdėdamas metilamino, palikdamas maišyti 10 m, kaip yra, tada po truputį per 20-30 min. įdėdamas dmso. tada įpilama vandens kartu su šiek tiek etilacetato ir maišoma dar kelias minutes, paliekama atsiskirti. praskiedžiama šaltu acetonu ir nusodinama, bandžiau ir 33, ir 37,5 HCl, jokio pastebimo skirtumo.
Iš visų mano taikytų procedūrų ši buvo švariausia ir duodanti didžiausią išeigą, be to, manau, kad kuo didesnė skalė, tuo geriau pavyksta.
Iš visų mano taikytų procedūrų ši buvo švariausia ir duodanti didžiausią išeigą, be to, manau, kad kuo didesnė skalė, tuo geriau pavyksta.
Great question! When flushing a column in chromatography, the goal is to remove any residual compounds from the stationary phase to ensure a clean system for the next run. The choice of solvent and whether to include water depends on the properties of the solvents used during the chromatography process.
Why Add Solvent Along with Water for Flushing?
1. Solvent-Solvent Compatibility: Many organic solvents (e.g., ethyl acetate, DCM, hexane) are immiscible with water. If water is used alone, it may not effectively remove nonpolar residues. Adding an organic solvent ensures that both hydrophilic (polar) and hydrophobic (nonpolar) residues are washed out.
2. Effective Column Cleaning: If the mobile phase was a mixture of organic solvent and water (e.g., ethyl acetate/water or MeOH/water), using both in the flush prevents precipitation of residual materials, which can clog the column.
3. Preventing Phase Separation Issues: In some cases, a solvent switch from an organic solvent directly to water can lead to phase separation, causing bubbles or irregular flushing. Using a miscible solvent before introducing water ensures smooth transitions.
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If Starting Solvent is Ethyl Acetate (EA) Instead of DCM?
Ethyl acetate (EA) is more polar and water-miscible to some extent, whereas DCM (dichloromethane) is less polar and immiscible with water. The flushing strategy changes depending on the starting solvent:
For EA: Since EA is slightly water-miscible, a water wash alone may work to some extent, but using a mix of EA and water ensures better residue removal.
For DCM: DCM is completely immiscible with water, so a transition solvent (like methanol or ethanol) is often used before adding water.
Practical Approach:
If you used EA as the mobile phase, first flush with EA, then follow with a more polar solvent (e.g., methanol), and finally with water.
If you used DCM, first flush with DCM, then use a bridging solvent (MeOH or IPA) before introducing water.
Hope this helps! Let me know if you need more clarification.
Why Add Solvent Along with Water for Flushing?
1. Solvent-Solvent Compatibility: Many organic solvents (e.g., ethyl acetate, DCM, hexane) are immiscible with water. If water is used alone, it may not effectively remove nonpolar residues. Adding an organic solvent ensures that both hydrophilic (polar) and hydrophobic (nonpolar) residues are washed out.
2. Effective Column Cleaning: If the mobile phase was a mixture of organic solvent and water (e.g., ethyl acetate/water or MeOH/water), using both in the flush prevents precipitation of residual materials, which can clog the column.
3. Preventing Phase Separation Issues: In some cases, a solvent switch from an organic solvent directly to water can lead to phase separation, causing bubbles or irregular flushing. Using a miscible solvent before introducing water ensures smooth transitions.
---
If Starting Solvent is Ethyl Acetate (EA) Instead of DCM?
Ethyl acetate (EA) is more polar and water-miscible to some extent, whereas DCM (dichloromethane) is less polar and immiscible with water. The flushing strategy changes depending on the starting solvent:
For EA: Since EA is slightly water-miscible, a water wash alone may work to some extent, but using a mix of EA and water ensures better residue removal.
For DCM: DCM is completely immiscible with water, so a transition solvent (like methanol or ethanol) is often used before adding water.
Practical Approach:
If you used EA as the mobile phase, first flush with EA, then follow with a more polar solvent (e.g., methanol), and finally with water.
If you used DCM, first flush with DCM, then use a bridging solvent (MeOH or IPA) before introducing water.
Hope this helps! Let me know if you need more clarification.
, appreciate guidance on them. Here we go...