In series fraction, I’m on butanol solvent, when I added it to my water+extract base, on First addition it separated water clearly, on second addition of butanol it dissolved half of my water fraction(out of 400ml 100 ml left) while adding butanol solvent for the 3rd time, only few ml are left, while in other seperating funnel water fraction has completely dissolved. Can someone please guide me what could be the reason? And how to restore my water fraction?
n-Butanol (1-butanol) is partially miscible with water so it cannot dissolve all the water fraction. Of the alcohol isomers, (having the formula C4H9-OH), the only compound which is totally miscible with water is tertiary-butanol or 2-methyl-2-propanol. I suspect that you used t-butanol since ,sometimes, (due to some human errors) the bottles of these alcohols are interchanged . Before using any isomer of these in your research, please carry out two simple qualitative tests to confirm that it is e.g. n-butanol.
As Nizar mentioned, n-butanol is partially miscible in water. This seems to increase when I don't centrifuge my samples, probably due to water forming a suspension in the butanol fraction. So you could try centrifuging you samples if possible.
To fix the miscibility, I usually saturate my butanol with water before using it for extraction. You can do this by simply adding water to the butanol and shaking it and letting it separate. Keep the water and butanol mixture, but make sure you only pull from the butanol phase. This method will reduce the water loss in your samples. Another strategy is to simply add extra water before you add the butanol.
Nizar Matar respected Sir, no I have used n butanol, please find pics, this is the recent condition of fraction and the solvent bottle.
Ryan Wheeler thank you so much for your kind response. should I add double distilled water in it to separate more water fraction or should I collect it As it is?
Respected Fariha Imtiaz, I have taught practical organic chemistry (1,2, and 3) possibly around 100 times during my career. I am NOT praising myself but I wanted to make a point: Through the years, I saw interchanged or mixed-up contents of bottles of alcohols most probably due to human error.
It is easy to carry out simple tests to confirm that you have primary alcohol such as butan-1-ol and NOT tertiary alcohol such as t-butanol.
One of my English PhD colleagues & friends used to test & purify every material before reacting it during his research and that was a correct scientific path.
Fariha Imtiaz, at this point I would separate the remaining water.
I'm assuming that the compound you are trying to extract is in the butanol fraction? If so, you should add DD water to the separated butanol fractions to clean them. When the volume of water is reduced this much, it can sometimes force undesired compounds into the butanol fraction (salts especially). With the volumes that you're working with, I think 50-100 mL of DD water should be enough to do this. Just proceed as if you are extracting the butanol fraction with water, and be sure to save all of your fractions, just in case.
Ryan Wheeler no, I am not sure which fraction would be active, at this phase I’m pooling all Fractions from different solvents.
so, should I Add that 50-100ml DD water from butanol Into water fraction Or Discard it after washing?
Thank you so much it’s very helpful.
Fariha Imtiaz, I understand. I would add the DD water directly to the water fraction. It would restore the volume that you lost as well as any compounds that should not have been removed.
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