I was curious to know if BnOH could be oxidised by FeCl₃ to produce benzaldehyde and FeCl₂:
2 FeCl₃ + PhCH₂OH → 2 FeCl₂ + PhCHO + 2 HCl
Or w/e.
Since we are under lockdown, my resources at this time are tantamount to nil, so I created FeCl₃ by dissolving staples in hydrochloric acid, and
when it was done I added a few beads of sodium percarbonate to turn Fe²⁺ into Fe³⁺. Then, in a small plastic grad cylinder, I poured into that
FeCl₃ acidic solution a few drops of benzyl alcohol, and let it sit at room temperature.
There was a faint almond scent, but almost nothing during day 1 and 2. Tonight, I got fed up and decided to call it a day, but on cleaning the
cylinder, I suddenly noticed a much stronger smell, much too strong to be benzyl alcohol, which doesn't at all recall almond perfume like
benzaldehyde. I wonder if that wasn't toluene (or benzene?).
TBH, I have a 1 l bottle of benzene in my lab, but I never opened it as yet, so I am unable to be definitive. Could FeCl₃ induce (more than
catalyse, because 96 h of reaction time doesn't make much of a catalysis) the de-alkylation of benzyl alcohol into toluene/benzene?
Either a "SN₁" of the alcohol (in which case, the FeCl₃ is just spectator):
PhCH₂OH + H⁺ → PhCH₂(OH₂)⁺ → PhCH₂⁺ + H₂O (with the carbanion stabilised by resonance Ph-CH₂⁺ ↔︎ ⁺Ph=CH₂)
Then: PhCH₂⁺ + Cl⁻ → PhCH₂Cl
Or a full Fr-Cr de-alkylation with creation of benzene and some chlorinated methane compound.
Opinion?
[Edited on 13-4-2020 by Keras]clearly_not_atara - 13-4-2020 at 11:59
Sounds like benzyl chloride, especially if the smell was sharp and acidic. Since you were using peroxide+acids, phenol is another possibility by a
Baeyer-Villiger reaction.Keras - 13-4-2020 at 12:02
Sounds like benzyl chloride, especially if the smell was sharp and acidic. Since you were using peroxide+acids, phenol is another possibility by a
Baeyer-Villiger reaction.
Yeah, you must be right, benzyl chloride is more likely via a SN₁ sort of reaction where the OH group is protonated then leaves, being replaced by a
chloride ion.brubei - 13-4-2020 at 15:19
Sure, I should do so, but without any reference compound to judge the spots against, and without anything to perform TLC with except acetone and paper
towel, I'm not sure the results would be meaningful anyway…
Bon courage ! brubei - 14-4-2020 at 08:48
Doing "research" without analytical material require a lot of courage SWIM - 14-4-2020 at 09:59
For future reference, benzene doesn't have a strong odor.
It has a light odor that many might describe as pleasant. At least at moderate concentrations.
Don't know how much sense this makes but I would say its smell is sort of like the taste of glycerine.
As for confirmation of identity without TLC; you could always try hydrolysis.
And another smell test.
I can't think of any other likely products which could be de-odorized as easily by mild conditions.
(I'm assuming the product may have been just a trace and collecting it for other old-time identification tests like forming derivatives wouldn't be
practical.)
