Hi, I was really confused on the correct answer choice here. According to my Kaplan organic chem book, it says fractional distillation is ONLY used when the two compounds have boiling points less than 25 degrees apart, so how can this be the answer when the boiling points of the two compounds of interest are 97 degrees and 197 degrees? thanks!
AAMC #10 question 101
- Thread starter Vikas03
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You should probably include the full question. Choosing which method is most appropriate is usually a process of elimination. You're right, fractional distillation takes a long time and is thus typically reserved for compounds with close boiling points. But if simple distillation was not offered as an answer choice and the other answer choices were inappropriate, that's the best option you have. Hard to answer without knowing what the questions/options were.
Two choices states extracting via ethanol or water (but both of the compounds of interest were told to be soluble in water and both had OH groups in them), third choice mentioned recrystallization but we weren't given any information regrading their solubilities at different temperatures, and last answer choice was fractional distillation and we were told they have boiling points 100 degrees apart.
you just answered your own question:
cant extract because structures are too similar.
you can recrystallize basically any solid, you just gotta use the proper solvent.
distillation would be the easiest to separate because the bps are so different.
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Pretty sure that fractional distillation can be used any time. It is just better to use when the boiling points are very close.
Yes, fractional distillation can be used anytime, but is especially useful when the boiling point difference is <30 degrees. For such a large BP difference, fractional distillation will more than suffice even though simple distillation will have a higher yield.
