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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: Schrödinger on June 01, 2016, 05:16:37 PM

Title: Potassium Benzylamide
Post by: Schrödinger on June 01, 2016, 05:16:37 PM
A simple salt metathesis reaction, I tried making the potassium salt of benzylamine (PhCH2NH2).

PhCH2K + PhCH2NH2  :rarrow: PhCH2NHK + toluene

I expected to see a white solid, PhCH2NHK. Instead I get a pink solid. Is this its real colour? Or am I doing something wrong?
Title: Re: Potassium Benzylamide
Post by: discodermolide on June 02, 2016, 01:13:48 AM
This may well be its actual colour.
Phenyl acetic acid is used to titrate n-Butyllithium, when the acid group has beed fully consumed the strong base starts to deprotonate the PhCH2- group to give a yellow colour, the end point of the titration. Point is that many of such anions are coloured.
Title: Re: Potassium Benzylamide
Post by: Schrödinger on June 02, 2016, 12:20:57 PM
I'm starting to believe it too. I did a lithium version of the reaction (in THF) and that turned out pink too. But then I pumped on it for a while to remove the solvent, and after 3 pentane washes, it now seems white. Perhaps it's a solvent thing... It might also be because of THF.