moonfisher
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Boron esters
Let's say you make an ester of boric acid and cis1-2Cyclohexanediol. How would the crystal structure look like? I'd think it would be a horrible mess,
and a polymer. Probably inflammable, too.
Well, good chemists shouldn't lick their fingers, anyways
-Life advice from Sir Martyn
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j_sum1
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Cool question. Paging chemplayer.
I suspect the answer to the question would be simpler if you used a regular alcohol rather than a diol.
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Ozone
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Because you are dealing with a diol, and they are on the same plane, I'm thinking that you will get (mostly) the neutral boronic ester...and some
polymeric crap (considering reactivity of boron with the empty shell, and all). pH will be very important, I'm thinking.
See:
http://www.wiley-vch.de/books/sample/3527325980_c01.pdf
Aside, these are usually stable, but will hydrolyze in water. You should be able to isolate them without fear of fire (quite boring, actually).
Although many have had some luck, I cannot guarantee you will get crystals. It might be a challenge, but it shouldn't be pyrophoric.
The cyclic boronic ester is a serious driver here. It will probably do that before all else (or it will settle on this configuration). We used to do
this to speciate carbohydrates by virtue of hydroxyl orientation. But, we did this in DMSO (water, as mentioned, will FUBAR a quantitative
measurement). So, you may wish to include a very small amount of water to maintain an equilibrium until the product distribution settles down. Look
at the stoichiometry.
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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moonfisher
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Quote: Originally posted by j_sum1  | Cool question. Paging chemplayer.
I suspect the answer to the question would be simpler if you used a regular alcohol rather than a diol. |
Well, it would but then it would not be worth asking!
O3, thanks for the reference. Will make for some light bedtime reading. It will be an interesting challenge, for me at least. The hydrolysis sounds
like a pain in the ass. How much of a FUBAR are we talking about? Should I go for a utterly anhydrous setup, or just dry things well?
Well, good chemists shouldn't lick their fingers, anyways
-Life advice from Sir Martyn
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Ozone
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We were doing this in distilled DMSO, which is both a supreme pain in the ass and probably unnecessary (unless you are wanting ppm quant), and dilute
(key, here). For gram-scale synthesis, it would just be checked off in the usual means that explain "loss of yield." Unless it was really wet. So,
expect (depending on time, temp., concentration, acid/base, etc.) stoichiometric hydrolysis relative to water.
This may actually help you, though, as a small amount of water, I believe, may help to get only the cyclic compound (more stable than singly bound
boronic esters).
I suppose you just do the experiment and see how it goes. The experiment shouldn't be too rigorous, and the results should be both interesting
(particularly if gloop results) and instructional.
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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moonfisher
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Thanks for all the help, but it turns out my cyclohexanediol was even shittier than I thought. Might need to make a new batch. Something for a rainy
day...
Well, good chemists shouldn't lick their fingers, anyways
-Life advice from Sir Martyn
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