All of my compounds are pure except grease (0.86 m and 1.25 br s in CDCl3). I am not able to recrystallise some compounds and they are obtained as sticky solid. Please suggest me some methods to remove grease. It would be useful if I can avoid the column again.....Thanks
Dear Chinmay,
Grease can be removed by n-Hexane or Pentane.
Hoping this will be helpful,
Rafik
You can triturate/precipitate it with the combination of ether (minor) and hexane (major)
The easiest way I always use is to pass it through a very short silica column of about 4-5 cm (chromatography) and elute it with a low polarity solvent like DCM/pet. ether so the grase stays in the baseline. I hope it helps
If grease is a persistent problem in several of your compounds, you should try to find the source of this grease and avoid your product contamination in the first place. E.g.: If it is coming from solvents in your reactions/columns, try to distil them first; if you are applying grease to seal your flask, reduce it use (most of the time this common practice is not crucial for common reactions); be sure of cleaning properly your NMR tubes in the outside with tissue paper or a cloth (sometimes I have found grease peaks in the NMR samples that actually were caused by my own fingerprints outside of the tube!, they disappear just wiping the tube a little bit... XD); also avoid emplying plastic labware or plastic syringes to prepare yuor NMR samples. Good luck!
Dear Chinmay Bhat
The best way to remove the grease is to wash the precipitate well with pet.ether 40/60 or 60/80.
Good luck
Add some zinc oxide to the solution and take your compound from the filtrate after filtration
Dear Chinmay Bhat ,
Try this: during recrystalization process add some active charcoal in solution, and filtrate. Grease will be adsorbed on the active surface of coal and remains on the filter paper. You can repeate this process.
All best!
suspend the compound in n-hexane and heat it while stirring for some time. Filter the product and washed with hot hexane and finally dry it under vacuum. The procedure is well applicable if the product is insoluble in n-hexane.
load the crude compound on charcoal and elute it with low polarity, still if your compound like sticky solid try scratching in cold n-pentane
Hello, you can remove it washing with n-pentane your sample (if is not soluble in n-pentane) and collecting the solvent with a pipette.
You can remove it filtering your compound using a pipette with some cotton wool in it and using EtOH. It has worked for me some times. It is a very quick method.
For the removal of grease from an organic compound wash it with n-hexane or pet-ether as less polar solvents.
You can use of n-hexane or petrelum-ether as less polar solvents for removing of grease .
I have found useful to carry out a filtration using a Pasteur pipet with a little bit of cotton wool inside and using absolute ethanol as solvent to dissolve the compound you want to clean of grease. It has worked for me many times!
I washed.my compound several.times with hexane and pantane by grease peak is not removing any other methode to remove the grease peak that is oily sticky compound
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