Sciencemadness Discussion Board

KOH/NaOH azeotropic dehydration

oberkarteufel - 4-3-2019 at 01:13

As I'm struggling with potassium production and I see treason everywhere, I suspect that my KOH may contain a wee bit too much moisture for the reaction to work.
I came up with the idea that maybe the hydroxide could be dehydrated through azeotropic distillation with toluene. However, I don't put much hope in this, as I was unable to find any traces of anyone trying this before. Can this work or it's all just my delusions and false hopes?

//I am aware that I could melt the hydroxide, but currently I have no place to do it safely.//

12thealchemist - 4-3-2019 at 03:48

My guess is that this won't work due to the high affinity of KOH and NaOH for water. This is typically why these are melted to dry them. I don't know if xylene boils hot enough to remove the water (140°C) but I suspect this isn't the case.
On a chemical front, have you tried heating the KOH/Mg/paraffin oil up to about 150°C until no more hydrogen is produced before then heating to 200°C? This will extend the "reaction" time and consume magnesium, but it will dry the KOH and paraffin oil before any potassium will form.

oberkarteufel - 4-3-2019 at 23:50

Your guess was correct, I guess ;) I've tried to dehydrate KOH using toluene and then xylene using Dean-Stark apparatus. In both situations the amount of water distilled off was negligible, as there wasn't enough to even separate out as a distinct layer of a distillate. KOH just kinda clumped into a single blob at the bottom of the flask.
So, case dismissed.

"K topic" will be continued here: ;)