Solubility and reaction of compounds

[kfsa1]

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Hi guys,

I was wondering what exactly is the criteria needed for solubility? I always thought the like dissolves like = whenever compounds are able to form intermolecular bonds it means they become soluble. Or, if two compounds react with one another E.G base + acid, they are soluble in one another.

My question came up because of AAMC 4 question 153 where they ask what two functional groups compound C is most likely to have based on its solubility.

Thanks

 

[loveoforganic]

Solubility is driven by enthalpy, entropy, and temperature (dG=dH-TdS). dH is accounted for by the formation of attractive intermolecular interactions. Entropy is more complex.

More specifically to your question, you'd look for a functional group that had an attractive interaction with the solvent or a functional group that reacted with the solvent in such a way as to form a functional group that interacted attractively with the solvent (e.g. Formation of a caboxylate from a carboxylic acid functionality upon reaction with a basic polar solvent)

 

[kfsa1]

So most of the time with some exceptions, a base would be soluble in acid and visa versa?

The question that I am trying to answer is this:

Compound C is soluble in both dilute acid and base. What functional groups is this compound most likely to have?

A) COOH + Amide
B) Amine + Amide
C) Amide + Nitro
D) COOH + Amine.

I was wondering about the solubility issue bc if an acid is soluble in both base and acid, could the answer potentially just include an acidic or basic functional group? (although it has two functional groups included in each choice)

Thank you.

 

[loveoforganic]

Yes, but I think there's a clear best choice out of those. Like dissolves like refers to polarity. To the extent that similar fg's have similar polarity, like dissolves like applies to fg's. However, you really have to consider te entire molecule. A hydroxylated cholesterol isn't going to be readily soluble in water, for example.