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Author: Subject: Triethyl borate and triisopropyl borate
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[*] posted on 8-3-2018 at 14:44
Triethyl borate and triisopropyl borate

I want to play with boric acid esters but since trimethyl borate forms an azeotrope with methanol, which is quite poisonous I am wondering how it will work with ethanol or isopropanol. At the time i'm not able to check this by myself but maybe You have some experience with this that could help me further. What I want to know is how brightness of these 3 esters is comparable to each other since they have different volatilities. And how the distillation works with EtOH ans IPA (bp of azeotropes or any special hints)
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[*] posted on 8-3-2018 at 17:50

First of all, methanol's toxicity is overrated, and you pretty much need to drink it in order to be poisoned. All poisoning cases I'm aware of seem to have resulted from some poor soul mistaking it for ethanol.

To get the ester to form, you have to do a really good job of removing water. If you have a very dry alcohol, this will happen to a fair degree all on its own. It's hard to find really dry ethanol, but much easier to find really dry methanol.

Isopropanol will have a less visible color because it burns with a yellow flame, indicating carbon particles are forming. However, if ethanol and methanol are both out, all is not lost! Propylene glycol works well for this too, if you give the esters plenty of time to form. Or just heat boric acid with propylene glycol, with an excess of the latter. You should be able to see a brilliant emerald-green flame. :)

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[*] posted on 9-3-2018 at 07:30

You should worry more about borate's toxicity than methanol's.Although borate is also not that toxic.
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[*] posted on 9-3-2018 at 07:51

See my post “Preparation of Methyl Borate” in Prepublication.

The single most important condition for a successful synthesis is good mixing - Nicodem
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