Compound Separation

[Mushrooomboy]

---

Members do not see this ad.

I may be wrong, but when I was answering this question, I thought both compounds were bases because of the hydroxyl group, so reacting both with bases would yield the same result?

 

[hueso]

The compounds are weak acids. When dissolved in ether, the stronger of the two (aka the one with the lower pka) will react with NaOH to form its alkali salt and go into the aqueous layer. The stronger acid will be the phenol, compound I.

 

[Teleologist]

The compounds are weak acids. When dissolved in ether, the stronger of the two (aka the one with the lower pka) will react with NaOH to form its alkali salt and go into the aqueous layer. The stronger acid will be the phenol, compound I.

Compound one isn't phenol. Looks like toluene with a para hydroxyl group.

 

[hueso]

Compound one isn't phenol. Looks like toluene with a para hydroxyl group.

Also known (by IUPAC) as 4-methylphenol.

 

[NextStepTutor_1]

Both of these 2 compounds, regardless of their specific nomenclature, are alcohols (a hydroxyl group bond to a carbon). Alcohols are very weak acids (a pKa of around 15!), but acids none the less. A hydroxyl group is not indicative of a base. Another compound illustrating this being a carboxylic acid, which is a stronger weak acid (still weak with a pKa of around 5) that has a carbonyl group and a hydroxyl group.

Cheers!


http://forums.studentdoctor.net/forums/next-step-mcat-tutor-office-hours.970/

 

[Teleologist]

Both of these 2 compounds, regardless of their specific nomenclature, are alcohols (a hydroxyl group bond to a carbon).

Bruh,

Alcohols - Compounds in which a hydroxy group, –OH, is attached to a saturated carbon atom R3COH. The term 'hydroxyl' refers to the radical species, HO..

http://goldbook.iupac.org/A00204.html

 

[Chrisz]

Coumpond 1 is phenol while the second compound is benzyl alcohol.
Phenol has pKa of 9-10 while benzyl alcohol very close to satuated alcohols, pKa 15-16. These two have quiet a big difference in pKa, so could be easily separated.

 

[NextStepTutor_1]

Good catch, @Teleologist!

 

[The Brown Knight]

The phenol is quite acidic for an alcohol due to some awesome resonance stabilization of negative charge on the conjugate base, but the benzyl alcohol is a much weaker acid since it lacks this resonance stabilization.
Having said that, the methyl group para to the alcohol actually makes the whole thing LESS acidic, but that's beside the point. (If only they had a nitro group there instead of methyl...)