[mir]

Ok, here is a problem:
I have 5 mL of Acetic acid with aboout 3 mmol of a phenol (1,3-dimethexy 4-hydroxy benzene). I add 6 grams of sodium bicarbonate to 100 mL of water. And I pour it stepwise into the solution containing the phenol, to quench it. The pH is 6.

Why dont I get my phenol completely out of the solution (of course, some will stay in the waterfraction, but not that much in theory)? I have tried Dichloromethane, Diethylether, ethylacetate (100 mL of each). What possible more could I use to extract the solution?

The waterfraction is deep red. The organic fractions is 1/10 of that colour.

TLC is showing phenol in organic fraction, but very little compared to the reactionmix.

I cant figure out what went wrong in my first step of workup?

[proufs]

Hi,  Have you tried restricting your use of water a bit?  Do you really need 100mL of sat. Na2CO3 to quench your reaction?  Anyway, consider to reducing the amount of water you use if at all possible and then extract with several (3-5qty) small portions (not larger than 5 mL) of cold chloroform (cool it for a few minutes to below zero on a dry ice/acetone bath).  Condense the combined organic layers under vacuum and I think you will find your phenol.  I work with 3-hydroxy-4-methoxybenzyl amines and use this procedure repeatedly.  I have found restricting the amount of water I use and the temperature of the extracting solvent to be the most helpful.  Also, I find better partitioning results at pH 7.5 but that's probably because of the amine functionality.

[mir]

Im curious: What have temperature to say in extraction? To avoid chloroform to evaporate and ease the handling of the solvent?

Thank you for your help. I will try chloroform and smaller volumes.
Btw - I didnt use saturated bicarbonate solution. I used ~~stochiometric amounts of the base to deprotonate the acid. Next time also will saturate the water with NaCl to make it even more polar.

How do you evaluate the partion when you are extracting? Using TLC or GC?

[proufs]

Hi,

As I recall, water is roughly 8% soluble in chloroform.  I think you can decrease the solubility of water in chloroform with a decrease in temperature.  Same should be true for the solubility of your phenol.  I used to separate my 3-hydroxybenzyl amines by precipitating them out of aqueous solutions by decreasing the temperature of the aqueous solution.  I like the previous method I mentioned much better.

I still recommend decreasing the amount of water you use.  Use a little stronger base if you have to.

When I referred to partioning, I was basically saying that I get better separations--and hence more product recovery from the extraction process.

All the best.