Let's see another sample problem.
This time you have a mixture of benzoic acid
and p-methoxyphenol,
dissolved in dichloromethane.
How do you separate these two compounds?
Answer: You cannot use 5% NaOH to separate these
two compounds. NaOH will react with both benzoic acid and p-methoxyphenol, thus
both compounds will be extracted into the aqueous layer.
Do you want to see what will happen
with 5% NaOH?
-
- See? Both compounds are extracted, so
you cannot separate them with 5%
NaOH.
NaOH was too strong a base, thus it does not differentiate the
strong and weak organic acids.
-
- Use of weak
inorganic base such as NaHCO3
will differentiate between the compounds.
-
- Strong organic acids such as benzoic
acid would be deprotonated and ionized,
while weak organic acids such as phenols would NOT be deprotonated.
-
-
-
-
-
- Did you see that you separated the two
compounds using sat.
NaHCO3 aqueous solution?
Let's continue then...
