Sciencemadness Discussion Board

Pentanoic acid extraction

morsagh - 21-4-2016 at 07:20

I prepared pentanoic acid by oxidation of amyl alcohol by KMnO4, but now i have 150ml of solution of KOH and pottasium salt of pentanoic acid. Is there any way hot to extract pentanoic acid from this solution without boiling out most of water?

Metacelsus - 21-4-2016 at 07:52

Pentanoic acid logP for water:diethyl ether is 1.24 (according to my table), so it should be possible to extract after acidification. I would expect similar values for other solvents. You'll probably want to extract repeatedly (at least twice) to ensure good recovery.

What's wrong with boiling off most of the water, so you can use a smaller amount of solvent to extract? Pentanoate won't decompose if you do that.

PHILOU Zrealone - 21-4-2016 at 10:04

Add an excess of HCl or H2SO4 and collect the oily layer on top.

DraconicAcid - 21-4-2016 at 10:08

Quote: Originally posted by PHILOU Zrealone  
Add an excess of HCl or H2SO4 and collect the oily layer on top.

Or very concentrated sodium hydrogen sulphate.

morsagh - 23-4-2016 at 07:11

It will take very long to boil of that much water

JJay - 23-4-2016 at 07:13

It won't take long to boil off 150 mL of water... I have boiled off 15000 mL of water several times in the past few weeks. That takes 100x as long.