Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: iScience on August 04, 2013, 08:06:22 AM
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well.. is it the fact that it's a good solvent? or is it something else?
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Acetone. I haven't heard it called dimethyl ketone ever. Sometimes I've even seen particular lazy people refer to it simply as "tone". It's pretty polar while still being aprotic and evaporates quickly enough not leave residue on glassware.
... that and it's absolutely dirt cheap.
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Ah ... I should have caught that sooner. So thanks you to gritch:. It seems to have been a meme, back in the day, that the last step of washing glassware was to rinse the last of the distilled water away with acetone, then "let it dry", so the moisture was gone. Funny thing is, "let it dry" doesn't mean the acetone has disappeared, its either in the room, or vented out the hood, and into the local atmosphere. So people are moving away from that. And of course, the truly lazy (like me in my undergraduate days) wanted to skip all the elbow grease washes and just soak in solvent to clean. But yeah, we're moving away from that. FWIW, if you're removing moisture, any water miscible volatile solvent (alcohols, acetonitrile) will work the same -- you've diluted the droplets of water with solvent to evaporate. Oh, and if you're using Piranha solution -- you definitely don't scrimp on the water washing, or the results are very dangerous.
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if it's just polar does't that mean oils won't get washed out that well? or anything non-polar?
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well.. is it the fact that it's a good solvent? or is it something else?
This is quite ambiguous. I think part of the answers have to do with it being relatively cheap, volatile, and organic. Several answers are about washing organics off glassware, if you were in an auto mechanic's shop (50 yrs ago?), you could say this about gasoline. It would be used just as commonly.
If you are referring to acetone's ability to dissolve other compounds, I'd be hard pressed to claim its superiority. It will depend on what you are trying to dissolve. Some people really like DMSO to dissolve things. It is more polar, but that also limits its ability to dissolve non-polar compounds. Acetone is in a nice neutral area, not too polar, but still with enough polarity. It is miscible with water and hexane. It is just right.
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It has intermediate polarity. It is miscible in both hexane and water.
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It's wide use is probably more economical than functional. It's a byproduct of industrial phenol production (used heavily by the plastic industry), so there's a lot of it made every year. Frankly I never had much use for it other than a convenient way to counteract the "permanent" effects of the almighty Sharpie.
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IMHO, the only thing acetone really is "good" for as a solvent (i.e. besides cleaning up) is the prpn. of alkyliodides from other halides, following the Finkelstein pathway (http://en.wikipedia.org/wiki/Finkelstein_reaction)
... as for most of the other reactions in organic chemistry acetone is too reactive in its own right
regards
Ingo
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well.. is it the fact that it's a good solvent? or is it something else?
Acetone is in a nice neutral area, not too polar, but still with enough polarity. It is miscible with water and hexane. It is just right.
even still, how would it effectively interact with the non-polar tail of an oil? and just to be sure, an oil is completely non-polar right? or does it have a polar head group?
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When you say "oil," do you mean triacylglycerol or petroleum oil?
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When you say "oil," do you mean triacylglycerol or petroleum oil?
well for oils with just a nonpolar tail component what would acetone do? it woudln't interact with it
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It would interact via London forces.
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okay, but that's an effective means of interaction only if there is a large surface area to interact with. there exists a large surface area on the non-polar oil tail, but for acetone, there is nothing like that. so how would it effectively remove non-polar hydrocarbon chains off of glassware? ie.. how does it effectively enteract with them?
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On the other hand, what makes glass so attractive to the nonpolar tails?
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oh hey! i think i got it. so you're saying, although just a monomer of the glass doesn't do very much, since it's in an array, the whole provide the large surface area required for the van der waal's interaction between it and the large non-polar tail?
which, if i apply this to the dimethl ketone case, since the dimethyl ketone is polar, the acetone species interact with each other cohesively and the oily tails interact via... well at this point wouldn't it be an induced dipole interaction? since there is a predominant electric field direction eminating from parts of the acetone (since it is polar), thereby inducing a dipole in the constituents of the oily tail resulting in a net attractive force; and basically this way, the dimethyl ketone is actually dragging the oily tails along with the rest of the acetone fluid? is this correct?
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a feedback would be nice for confirmation or rejection..
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I would describe acetone as only moderately polar (there is no hydrogen bond donor but there is one acceptor), but glass is quite polar (there are hydrogen bond donors and acceptors). Therefore, a nonpolar substance is more like acetone than silica.
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a feedback would be nice for confirmation or rejection..
I don't believe acetone is a good reagent for removing non-polar compounds. As I described originally, its used to remove water from a flask, or other vessel with a narrow neck, before drying. I've never used it to remove a sticky, non-polar substance from glass. I don't believe that a small molecule like acetone is non-polar enough to really interact with long hydrocarbon "oily" tails. So no, your conclusion on the other page:
oh hey! i think i got it. so you're saying, although just a monomer of the glass doesn't do very much, since it's in an array, the whole provide the large surface area required for the van der waal's interaction between it and the large non-polar tail?
which, if i apply this to the dimethl ketone case, since the dimethyl ketone is polar, the acetone species interact with each other cohesively and the oily tails interact via... well at this point wouldn't it be an induced dipole interaction? since there is a predominant electric field direction eminating from parts of the acetone (since it is polar), thereby inducing a dipole in the constituents of the oily tail resulting in a net attractive force; and basically this way, the dimethyl ketone is actually dragging the oily tails along with the rest of the acetone fluid? is this correct?
While technically correct in how you reasoned it out, doesn't describe what acetone does, so is simply wrong.
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Okay thanks guys!! :)