Pumukli
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Org. chem book based on pKa-s
Dear All,
Someone somewhere wrote on this board that there are organic chemistry books (org. chem. theory) which try to explain the subject for students mostly
via the differences in the pKa-s of various reagents.
Could anyone suggest me such a book?
I downloaded several "freely" available organic chemistry books from the web, but none of them fits this category.
Thanks for your help,
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Etaoin Shrdlu
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?
I don't see how that would even be possible.
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Metacelsus
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Many (most?) organic reactions are not acid-base. (For example, the Diels-Alder reaction.)
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BromicAcid
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Although it has probably been nearly a decade since I read it, Electron Flow in Organic Chemistry by Paul H. Scudder immediately comes to mind. I
just flipped through it and although the text does not center on pKa, it does incorporate it into thermodynamic/kinetic stability and transformational
energy to help students predict final products. I would recommend finding a used copy and giving that at try.
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BromicAcid
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My understanding would be that Pumukli is not looking at this from a traditional acid vs base standpoint. One wouldn't normally consider ethanol, or
water that acidic but if you have any reaction that involves a leaving group a understanding of pKa can help you predict if that reaction will take
place or what conditions you need to use to force that reaction to take place. I'm sorry if you already understood that Cheddite but it seemed you
were being a bit flippant on the subject.
One might ask: "Well, what about using a carboxylic acid as the leaving group? Reaction too slow, maybe a triflate will help. Stuck with that same
leaving group? What does the pKa look like in DMSO. Can I protonate it? Transform it? The pKa is too high.. the first step must be a protionation
of that leaving group, etc." Unfortunately for me, a lot of reaction mechanisms that I came up with in college fell to pieces when the pKa were
examined. Certainly a lot of this can be determined through trial and error, but the pKa system quantifies it.
[Edited on 3/7/2015 by BromicAcid]
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careysub
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Quote: Originally posted by BromicAcid  | | Although it has probably been nearly a decade since I read it, Electron Flow in Organic Chemistry by Paul H. Scudder immediately comes to mind.
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Thanks for the tip! I just scored a copy for $6.82 (including shipping) through BookFinder. Lots more copies out there cheap.
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Etaoin Shrdlu
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And with all the pKas in the world memorized, one still needs to understand steric hindrance, stereochemistry, regiochemistry, resonance, solubility,
etcetera and so forth...
Despite its importance I'd hesitate to suggest organic chemistry could be explained "mostly with the differences" of pKa.
That looks like a nice book. I picked up a copy as well.
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Polverone
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You might be thinking of Michael B. Smith's <i>Organic Chemistry: An Acid-Base Approach</i>: http://www.amazon.com/Organic-Chemistry-Acid-Base-Approach/d...
There's only 1 Amazon review and I haven't read it, so I don't know if it is any good.
PGP Key and corresponding e-mail address
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BromicAcid
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Spendy... but since it is being used as a textbook the floor will drop out on it sooner or later.
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Pumukli
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Thank you for the suggested books!
This acid-base approach sounds interesting and I was simply curious about examining org. chem. reactions through a different pair of glasses.
Now I know the titles to look for.
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Chemosynthesis
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I don't know if it was my comment before, as I have definitely made a comment about some teachers/books emphasizing pKa's before, and even find it
very helpful to consider the paradigm as instructional. It can answer many questions... however, I do want to point out that it should be used as a
guide only. I hate ever saying anything is without exception in the sciences. Take this excerpt from _The Art of Writing Reasonable Organic Reaction
Mechanisms_ by Grossman.
"Looking at pKb values won’t always give you the right order of leaving group ability.
For example, one can hydrolyze carboxamides (RCONR2) with strong aqueous base,
but one can’t hydrolyze alkynyl ketones (RCOC=CR), even though the pKb of -NR2 is 35, and the pKb of -C=CR is 25. The solution to this
apparent contradiction is that the N of the carboxamide is probably protonated before it leaves, so that the leaving group is not really -NR2 at all
but is HNR2 (pKb = 10). For the same reason, the ability of -CN to leave is considerably lower (relative to heteroatom leaving groups) than its pKb
would indicate. The electrophile structure, the presence of metal counterions, and the nature of the reaction medium are also crucial factors in
leaving group ability."
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