I tried to dissolve ferric chloride in propan-1-ol and I saw ferric chloride partially dissolve in it, but I couldn't identify which reaction had occurred. If any one knows about this, please give me your suggestions.
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$\begingroup$ Who said there is a reaction in the first place? $\endgroup$– Ivan NeretinSep 14, 2017 at 7:10
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2 Answers
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There is no reaction between propan-1-ol and iron(III) chloride because propan-1-ol isn't acidic enough to react with it. Instead, phenol reacts with iron(III) chloride because it is acidic enough to form either the phenoxide or iron-phenol complex. On this basis, aliphatic and aromatic alcohol are distinguished. The mechanism of reaction of phenol and $\ce{FeCl3}$ can be found here.
According to this quora post:
Ferric chloride test is specific for determination of phenol presence. So as mentioned above, phenol is more acidic and can form phenoxide anions. This can form complex with Fe(III) in $\ce{FeCl3}$, which has a blue/green/red color depending on the nature of the phenol. Alcohol is too weakly acidic to even form the alkoxide or the complex.
So what's happening?
It actually forms a sol-gel. It is a part of iron-oxide based gels.
One noble application of this is non noble metals electrocatalysts for high temperature PEM fuel cells. For this purpose, Fe-containing carbon aerogels were prepared in resorcinol-furfuraldehyde resins. The resins are made in premixed solution of $\ce{FeCl3}$ and propanol.
answered Sep 14, 2017 at 13:36
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1$\begingroup$ This answer is thoroughly wrong. What even gave you the idea to cite this nonsense from quora? $\endgroup$– MithoronSep 14, 2017 at 13:51
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1$\begingroup$ @Mith I'm curious (since my knowledge of Org. chem. is limited to what I've learnt at school): As far as I know the ferric chloride test is one method to detect phenols (so that bit seems okay). The thing about alcohols not forming alkoxides seems off though (Maybe it's correct in the context of the answer?) Agreed, Quora answers aren't always great...but what parts are wrong in the answer here? :/ $\endgroup$ Sep 14, 2017 at 15:11
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$\begingroup$ @Nilay Oh a pointer! The 3rd link (to the "iron-oxide based gels" bit) doesn't seem to work :/ $\endgroup$ Sep 14, 2017 at 15:11
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I would say there is not enough information for us to think about the reasons for your outcome. I would assume you had propan-1-ol, not propen-1-ol, as the latter is not really stable and rearranges given time.
Dissolving is a physico-chemical process, which involves some particular changes on molecular level (I never state FeCl3 is a molecule). I am not sure if it matters whether you chloride was hexahydrate or anhydrous, anyway, dissolving would include destruction of ionic bonds/ionic structure of FeCl3. Iron (III) ions would attract negative sides of propanol dipoles, which are represented by oxygen atoms and form a kind of complex coordinated compound with them.
The partiality of your dissolving may just be caused by limited solubility of FeCl3 in propanol.
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$\begingroup$ Sir can you suggest me any catalyst or reactant by which we get complete solubility of ferric chloride (II) in propan-1-ol. $\endgroup$ Sep 14, 2017 at 12:16
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$\begingroup$ I don't think you need really a catalyst. You might use just more propanol. $\endgroup$ Sep 14, 2017 at 12:40
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$\begingroup$ But I want to maintain the conc. of ferric chloride in propanol. If I use more propanol than conc of ferric chloride will decrease which is not helpful for me. $\endgroup$ Sep 15, 2017 at 5:14
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$\begingroup$ did you check FeCl3 solubility in propanol? Maybe you're trying to prepare an oversaturated solution... If that's fine, you may try to increase temperature while dissolving $\endgroup$ Sep 15, 2017 at 7:36
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