# Organic solubility question

1. Homework Statement
Which of the substances below is least soluable in water?

A. CH2OHCHOHCH2OH
B. CH3COCH3
C. CH3CH2COOH
D. CH3COOCH3

2. Homework Equations

3. The Attempt at a Solution

I think bith B and C are not possible since B can dissolve in water easily and C is acid which is soluable in water. But i don't know what to choose from A and D. I checked on the Internet, it says D is not easy to dissolve in water, but my teacher told me he thinks A or B will be the answer. I totally think he is wrong at this point. Can anyone help me out with this?

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The least soluble will be the one that is least polar; A and C will readily dissolve because of the OH groups, so it's between B and D. I think esters would dissolve more readily than ethers, so I would choose B, but I could be wrong.

Hi there thanks for the reply, I think the answer is B, you are right.

For the comparison of B and D, I just found an answer

"Esters participate in hydrogen bonds as hydrogen-bond acceptors, but cannot act as hydrogen-bond donors, unlike their parent alcohols. This ability to participate in hydrogen bonding makes them more water-soluble than their parent hydrocarbons. "

http://en.wikipedia.org/wiki/Ester

And by the way, C is a COOH group (carboxylic acid) instead of OH.

I'm not sure what Wikipedia means by "parent hydrocarbons" since an ester is usually formed by combining a carboxylic acid with an alcohol. But I found this:

"Ethers are less polar than alkenes but not as polar as alcohols, esters or amides of comparable structure...." It goes on to state that cyclic ethers are more water-soluble than non-cyclic ethers.

This would support B as the right answer.

I just realize B is ketone, not ether.
Ketone is highly soluable in water.

So the answer will be D?

esters are not miscible with water. they form a separate oily layer. it is D.

A is glycerol. it has a relatively low Mr. it forms H-bonds in water, and is therefore soluble.

chemisttree
Homework Helper
Gold Member
Kushal is correct.

I have another question.
What does the text mean by ester is more water-soluble than their parent hydrocarbons?
I thought the parent hydrocarbons refer to alcohol and carboxylic acid.

chemisttree