Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: lukas.stib on October 14, 2019, 09:19:54 AM
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Hello chemists,
please, what is the better start of esterification carbox. acid and an alcohol; start to heat the first reactant that warms up to a temperature higher than the boiling point of ester, and add alcohol to this reactant, or add a small amount of the reactants mixture, heat up and when the ester begins to drip, I will drip the rest of mixture of the reactants as fast the ester drips?
Thank you.
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Mix everything together and run for about 2 h reflux, then change to Liebig cooler and do destillation. Your method I dont understand with the drips.
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If it is a small cheap alcohol like methanol or ethanol, I would simply mix the carboxylic acid into a container with the alcohol as a solvent (huge excess), add a drop of sulfuric acid and let it stir overnight.
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Thank you for your answers. I ask you because I read better results will be obtained by immediately removing the ester, because water is also produced, and yield decreases.
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Yes its a good idea to remove water but if you can use the alcohol as a solvent, just reflux it together with some sulphuric acid. Few drops might be enough but sometimes more is neded
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If its the methyl ester you're going for, just using wet bench methanol with a drop of sulfuric acid stirring at RT in a capped erlenmeyer has always yielded quite good results for me (read: quantitative conversion, or at least the bit residual carboxylic acid was easily removed by aqueous wash to yield pure product)
Probably doesn't hurt to stack the deck by using anhydrous alcohol, at reflux, with more sulfuric acid though :).
You can also use a Dean-Stark setup with benzene or toluene if your esterification is recalcitrant. That will remove water from your esterification as it proceeds. Or also set it up so that the vapor condenses over activated molecular sieves and drips back into the reaction dry from an addition funnel or soxlet extractor.
Basically, a lot of ways to get this done!