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From:
Richard Cryberg <[log in to unmask]>
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Informed Discussion of Beekeeping Issues and Bee Biology <[log in to unmask]>
Date:
Thu, 21 Sep 2017 23:49:47 +0000
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No I can not provide a cite for ethanol.  There are several cites for oxalic acid solutions in glycerin solutions forming esters with oxalic acid including the solution just standing at room temp that pop up in a google scholar search.  Most of those cites are quite old.  I did glycerin experiments where I dissolved oxalic acid in glycerin and held at 60 deg C for 15 minutes before rapid cooling and showed considerable ester had formed under those conditions.  As I recall those conditions were enough to convert 30% of the acid to ester.  No added catalyst is needed as oxalic acid is a strong enough acid by itself to catalyze ester formation.  I simply assume that as it is so very easy to make the ester with glycerin it would be amazing if the ester did not also form equally well with ethanol.

There are also all kinds of lit cites on the decarboxylation of glycerin mono oxalate.  Decarboxylation starts at a temp around 100 deg C and I confirmed this is the case by showing glycerin solutions of oxalic acid start to give off carbon dioxide gas at that temp.  At slightly higher temps the decarboxylation is rapid and quantitative forming glycerin mono formate.  The free acid from the remaining esters and probably traces of oxalic acid plus the water released during ester formation will result in hydrolysis of the glycerin formate with formic acid distilling off the heated system.  In fact this chemisty years ago was a convenient lab method to make formic acid.

Most of the above glycerin solution work was reported back before physical organic chem was invented so few rate constant measurements are reported.  I do not recall off hand if I found any.

Dick

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