reactofurnace - 17-7-2015 at 08:08
So Like any soapification reaction i measured an amount sodium hydroxide solution and the ester(ethyl propanoate) then i began a reflux for 35
minutes. Then i refluxed for 1 hour MORE because the ethyl propanoate was not reacting. Final hour the total time of 2 hours and 25 mins the ethyl
propanoate had kinda react. i could tell that the react had some progress because at one point i smelt the rancid smell of propanoic acid evolving.
Can anyone explain why this happened
P.S. the same reaction was perform with methyl acetate and was successful in just 20mins.
https://www.youtube.com/channel/UC3gqx2zhUyLdeGIAFyiwPYg
DJF90 - 17-7-2015 at 09:50
I suspect a fair bit of your problem is that the reaction is biphasic. In the case of methyl acetate, it has relatively good aqueous solubility and so
the saponification proceeds relatively quickly.
I have two suggestions for you; either use (more vigorous) stirring, or employ a co-solvent (ethanol is a good choice as it facilitates recovery of
the alcohol product, but if you're only after the propionate then you could use methanol or THF).
You should not be able to smell propionic acid as that would indicate a deficit of hydroxide; I'd suggest using 3 to 5 eq. NaOH as (6 M aqueous
solution).