# What's the identity of the crystalline solid in the following reaction? [closed]

A mixture of toluene, benzoic acid, aniline and phenol was dissolved in diethyl ether and extracted with 5% $\ce{NaHCO3}$ solution? This extract was acidified until a white crystalline compound appeared. What is the identity of this compound?

I had this question in my exam today. The answer is benzoic acid but I wanted to know how.

Well what you are doing here is trying to extract it by making it slightly alkaline using water, as water and diethyl ether seperate anything that is only soluble in alkaline water will be extracted from the organic phase. Of course toluene and aniline won't do much if $\ce{NaHCO3}$ is added. For phenol and benzoic acid it's just about the base you are using. $\ce{NaHCO3}$ is not strong enough to deprotonate the phenol. For benzoic acid, the acid is strong enough to be deprotonated by $\ce{NaHCO3}$. When it is acidified the benzoic acid is formed again and precipitates.