[Rutherford]

In a balloon (V=100ml), 2.5g of phenyl-salicylate was mixed with 15ml of 10% NaOH. The balloon was connected with a cooler, and the content was reflucted on a sand bath for 1.5h. Through the cooled mixture, CO₂ was passed until saturation. Then the content was distillated, and 300ml of solution was collected (with water vapors are distillated only substances that make a two-phase liquid-liquid system with it). What organic compound was in the distillate and what compound left in the vessel?

NaOH causes the ester to hydrolyse, I suppose that CO₂ reacts with non-reacted NaOH. Now the part in the brackets confuses me. Explanation needed  .

[Hunter2]

Phenol will go over together with water. Salicylate will be left

[Rutherford]

Thanks, but I need a full explanation why is it so? You mean salicylic acid will left?

[AlphaScent]

Do you know what an azeotrope is?

[discodermolide]

In a balloon (V=100ml), 2.5g of phenyl-salicylate was mixed with 15ml of 10% NaOH. The balloon was connected with a cooler, and the content was reflucted on a sand bath for 1.5h. Through the cooled mixture, CO₂ was passed until saturation. Then the content was distillated, and 300ml of solution was collected (with water vapors are distillated only substances that make a two-phase liquid-liquid system with it). What organic compound was in the distillate and what compound left in the vessel?

NaOH causes the ester to hydrolyse, I suppose that CO₂ reacts with non-reacted NaOH. Now the part in the brackets confuses me. Explanation needed  .

It's a steam distillation, the phenol distills over with the water.

[Rutherford]

But why the phenol, why not the salicylic acid?
Azeotrope-I read in wikkipedia (http://en.wikipedia.org/wiki/Azeotrope), but I don't understand completely the definition, this part: "This happens because, when an azeotrope is boiled, the vapor it produces has proportionate constituents as the original mixture."

[discodermolide]

But why the phenol, why not the salicylic acid?
Azeotrope-I read in wikkipedia (http://en.wikipedia.org/wiki/Azeotrope), but I don't understand completely the definition, this part: "This happens because, when an azeotrope is boiled, the vapor it produces has proportionate constituents as the original mixture."

It is not an azeotrope it is a steam distillation. Phenol is volatile in steam, salicylic  acid not.

[orgopete]

But why the phenol, why not the salicylic acid?

I would imagine some salicylic acid could co-distill. However, you need to rethink the procedure. Is salicylic acid present?

[Rutherford]

But why the phenol, why not the salicylic acid?
Azeotrope-I read in wikkipedia (http://en.wikipedia.org/wiki/Azeotrope), but I don't understand completely the definition, this part: "This happens because, when an azeotrope is boiled, the vapor it produces has proportionate constituents as the original mixture."

It is not an azeotrope it is a steam distillation. Phenol is volatile in steam, salicylic  acid not.

That is because phenol has lower boiling point, right?

But why the phenol, why not the salicylic acid?

I would imagine some salicylic acid could co-distill. However, you need to rethink the procedure. Is salicylic acid present?

Now, when I look at the answer I see in the vessel left the salicylic acid skeleton without the oxygen atoms. What happened then with salicylic acid?

[discodermolide]

It is not an azeotrope it is a steam distillation. Phenol is volatile in steam, salicylic  acid not.


Now, when I look at the answer I see in the vessel left the salicylic acid skeleton without the oxygen atoms. What happened then with salicylic acid?
[/quote]


It formed the sodium salt by the reaction with NaOH?

for steam distillation see http://en.wikipedia.org/wiki/Steam_distillation

[orgopete]

It is not an azeotrope it is a steam distillation. Phenol is volatile in steam, salicylic  acid not.

Just reiterate the point of the steam distillation of salicylic acid and to correct my comment. The steam distillation of salicylic acid is noted in this Org Syn procedure, http://www.orgsyn.org/orgsyn/pdfs/CV2P0531.pdf. The reason salicylic acid does not steam distill is because it is not present.

Why was carbon dioxide bubbled in? What happened?

[Rutherford]

"It formed the sodium salt by the reaction with NaOH?"
But the sodium salt should hydrolise fast.
The substance that left in the vessel is the one in the picture. Why?
I thought that CO₂ should react with the NaOH that left, but why was it really added?

[discodermolide]

"It formed the sodium salt by the reaction with NaOH?"
But the sodium salt should hydrolise fast.
The substance that left in the vessel is the one in the picture. Why?
I thought that CO₂ should react with the NaOH that left, but why was it really added?

That must be a mistake, salicylic acid is present as the Na salt.
The CO₂ is used to remove any excess NaOH.
If you hydrolyse phenyl salicylate with NaOH you get phenol and salicylic acid sodium salt. You need a stronger acid than CO₂ to re-generate the salicylic acid, something like HCl.
NaOH and CO₂ gives you sodium carbonate.

p.s. NaOH will make the Na salt of phenol. Now this should be re-acidified by CO₂ to give phenol. Sorry I forgot that.

[Rutherford]

"If you hydrolyse phenyl salicylate with NaOH you get phenol and salicylic acid sodium salt. You need a stronger acid than CO2 to re-generate the salicylic acid, something like HCl."
You are right, I checked the pKa of salicylic acid and it is an almost strong one, so the conjugate base is very weak, meaning that water isn't able to donate its proton to it easily.

I got the following questions now that I can't understand:
1.On the wikkipedia link you gave is said that a mixture of  bromobenzene and water boils on a lower temperature that those two separately. What effect causes this?
2.If NaOH was added to phenyl-salicylate, there should be Na-phenolate present, too, but it is a strong base so it hydrolises rapidly. Is this correct?
3.The compound in the picture I gave is in the answer the substance that left in the vessel. Are the oxygen atoms missing because of an error (in typing), or that substance was really made in the process?

[discodermolide]

"If you hydrolyse phenyl salicylate with NaOH you get phenol and salicylic acid sodium salt. You need a stronger acid than CO2 to re-generate the salicylic acid, something like HCl."
You are right, I checked the pKa of salicylic acid and it is an almost strong one, so the conjugate base is very weak, meaning that water isn't able to donate its proton to it easily.

I got the following questions now that I can't understand:
1.On the wikkipedia link you gave is said that a mixture of  bromobenzene and water boils on a lower temperature that those two separately. What effect causes this?
2.If NaOH was added to phenyl-salicylate, there should be Na-phenolate present, too, but it is a strong base so it hydrolises rapidly. Is this correct?
3.The compound in the picture I gave is in the answer the substance that left in the vessel. Are the oxygen atoms missing because of an error (in typing), or that substance was really made in the process?

Number 1: No idea but I'll try and find out.
Number 2: I just corrected my post, answering this
Number 3: Yes, the oxygen atoms are missing.