CwisGons - 11-9-2021 at 20:45
Hello everyone. I have a dilemma. I wanna try to be more environmentally conscious so I will try to not use DCM anymore. However, this chemical is
used in a dinitrophenol extraction from a reaction mixture in this article:
sci-hub.st/10.1055/s-2003-42063
I use this synthesis to extract dinitrophenol. However, they use a lot for a small amount of product. So I would like to use a more environmentally
friendly solvent which I can make, like ethyl acetate and isopropyl acetate.
One problem I am facing is that dinitrophenol has limited solubility data. I look at ethyl acetate and according to Pubchem, about 15.55 grams of
dinitrophenol dissolves in 100 grams of ethyl acetate. There is however no data on the solubility of dinitrophenol in methylene chloride. This is all
I find:
Solubility at 15 °C (g/100 g solution): ethyl acetate 15.55; acetone 35.90; chloroform 5.39; pyridine 20.08; carbon tetrachloride 0.423; toluene 6.36
So I was wondering if ethyl acetate would be a better solvent for extracting DNP from the reaction mixture, since I see no solubility data to compare
it with. I also wanna try isopropyl acetate and see if that would be a good solvent. What do you guys think: should I try ethyl acetate or isopropyl
alcohol for the extraction?
Would DNP be more soluble in ethyl acetate or isopropyl acetate compared to methylene chloride?
karlos³ - 11-9-2021 at 21:53
You mean, you want a green(impossible), or I guess, rather a somehwhat green alternative for halocarbon solvents?
There is not really one and I doubt they find one.
But yes, judging by the solublity data, ethylacetate seems to be a better solvent than chloroform.
It might not stay as well in the solvents due to their higher miscibility with water.
But I think if you consider this and work accordingly, it won't be much of an issue.
Tsjerk - 12-9-2021 at 00:20
Always make sure the water you are extracting from contains a good amount of some salt to minimize the miscibility. Also when washing your solution
use brine instead of water or e.g. bicarbonate with brine instead of plain bicarbonate.
[Edited on 12-9-2021 by Tsjerk]
CwisGons - 12-9-2021 at 07:47
The procedure describes a somewhat neat reaction as the reagents are used and mixed in wetted silica, making it close to a solventless reaction.
CwisGons - 12-9-2021 at 07:48
Also, would isopropyl acetate work?
Texium - 12-9-2021 at 08:22
Ethyl acetate is my go-to solvent for extractions. It is generally a good alternative to DCM in that application. Isopropyl acetate would probably
work just as well, though it has a higher boiling point so it will be a little more annoying to evaporate/distill off of your product, especially if
you aren’t using a rotovap.
Don’t count on finding solubility data for anything. Generally there’s no point in fussing around with it. I work with a lot of compounds that
have no data at all, so I just use solvents that are known to dissolve similar compounds, and it’s generally fine. Likewise, isopropyl acetate is
very similar to ethyl acetate. You’d be hard pressed to find something that is soluble in one and insoluble in the other.