Assume that you have samples of the following two compounds, both with formula C₇H₈O. Both compounds dissolve in ether, but only one of the two dissolves in aqueous NaOH. How could you use this information to distinguish between them?

Question

Assume that you have samples of the following two compounds, both with formula C₇H₈O. Both compounds dissolve in ether, but only one of the two dissolves in aqueous NaOH. How could you use this information to distinguish between them?

Two chemical structures of compounds with formula C7H8O, one with a hydroxyl group and the other with a methylene alcohol.

Accepted Answer

Welcome back everybody. Our next problem says, imagine you are presented with two distinct compounds. Each sharing the molecular formula C eight H 10 0, both are soluble in ether. However, only one of them reacts with koh to produce a pin oxide. Use this information and distinguish the compound. So our first compound is a benzene ring. It has a hydroxy group and two methyl group substituents. Our next compound is a benzene ring and it has a 12 carbon chain with a hydroxy group at the end of the chain. So what distinguishes these two and which one will form a an oxide? Well, our first compound is a phenol. Our second compound is not, it's a benzene plus an alcohol group on an ike train. So the difference is how close that alcohol group is to the delocalized electrons in the benzene ring. So in the case of the phenol, the de localization of electrons in the ring, which the electrons on the oxygen can participate in gives that oxygen a slight positive charge, which is not how oxygen usually is when it's next to a carbon. Usually it would have a slight negative charge that makes it easier for it to lose the hydrogen. In addition, the carbon, since it's in the benzene ring is sp two hybridized, whereas the carbon bound bonded to the oxygen in our second compound is sp three hybridized and an sp two hybridized carbon is more electron than an sp three hybridized carbon. So that adds to that drawing of electrons away from the oxygen. So normally alcohols don't really lose their hydrogens. They, they aren't acidic, but phenol is acidic, it gives up its hydrogen fairly readily. In this case, we're reacting with potassium hydroxide, which is a really strong base and we quite easily get an acid base reaction. In addition, once we produce that fin oxide, which would have an O minus, so our product would be our benzene ring drop that with its double bonds, it's two methyl groups. Now with an O minus the de localization of the electrons. And again, that will include the electrons from the oxygen will help to stabilize the negative charge on the oxygen. And as we know, the more stable the associated bases, the more acidic the acid is. So the compound here that will react with potassium hydroxide to produce a pin oxide is our first compound R two for dimethyl phenol again, because the oxygen grouping directly on the benzene ring in a phenol will be acidic. While the alcohol group on the end of an alal chain will not have the benefits of that resonance from the benzene ring. See you in the next video.

Assume that you have samples of the following two compounds, both with formula C₇H₈O. Both compounds dissolve in ether, but only one of the two dissolves in aqueous NaOH. How could you use this information to distinguish between them?

Verified video answer for a similar problem:

Key Concepts

Solubility in Aqueous NaOH

Functional Groups

Ether Solubility

Assume that you have samples of the following two compounds, both with formula C7H8O. Both compounds dissolve in ether, but only one of the two dissolves in aqueous NaOH. How could you use this information to distinguish between them?

Verified video answer for a similar problem:

Key Concepts

Solubility in Aqueous NaOH

Functional Groups

Ether Solubility

Assume that you have samples of the following two compounds, both with formula C₇H₈O. Both compounds dissolve in ether, but only one of the two dissolves in aqueous NaOH. How could you use this information to distinguish between them?