anonymous one year ago List in order of most acidic to least acidic: $$CHF_2CH_2CH_2CO_2H$$ $$CH_3CF_2CH_2CO_2H$$ $$CH_3CH_2CF_2CO_2H$$ $$CH_3CH_2CH_2CO_2H$$

1. anonymous

Acidity is the measure of the tendency of acidic H to go in to the solution. C. is the most acidic, as two florine atoms are very electro negative, and pull on them the e- form the C, which after that pulls e- from COOH. |dw:1438626295009:dw| |dw:1438626474232:dw|

2. anonymous

For the other, you need to consider the distance of COOH from F atoms. C. B. A. D.

3. nincompoop

look for the size of the atom and the kind of atom that is most electronegative, look for the shape of the molecule and various partial charges

4. nincompoop

giving you the answer won't help you but providing you some of the tools to identify, you'll be able to solve this kind of problem yourself

5. nincompoop

a quick review helps look for David Klein's Organic Chemistry as a second language it is discussed in acid-base chapter

6. anonymous

Right, I had assumed the inductive affect would just entirely pull the electrons away so I think @Bozhena helped because it looks like it's more like every other one is sort of either helping or hindering the acidity.

7. nincompoop

induction is just one of the key things to look for when looking for acidity

8. nincompoop

orbitals count too

9. anonymous

So can I label it through like this to reason out if it will help or hinder it? |dw:1438627078381:dw| Since this places a partial positive on the oxygen, this will allow the Hydrogen to leave and of course the carboxylic acid is resonance stabilized.

10. nincompoop

11. nincompoop

|dw:1438627430132:dw|

12. nincompoop

oxygen is more electronegative than hydrogen and carbon so it shouldn't be partial + charge

13. nincompoop

|dw:1438627525767:dw|

14. anonymous

I was considering it based on it being kind of an alternant structure, see: http://chemistry.umeche.maine.edu/CHY556/Alternant.html But I agree, oxygen is not strictly positive, only partially more positive than it would have been normally. I'm starting from those two extremely electronegative fluorines as being partially negative, leaving some deficit of electrons at the carbon boned to those two. Since this carbon is quite positive, then the next over will be partly negative as a sorta wavelike effect that travels down the molecule weaker and weaker of an effect as it gets away from the Fluorines. Similarly this is kind of like the explanation for why halobenzenes are ortho-para directors and rarely add to the meta positions, so I'm sorta taking this kinda perspective but trying to place everything together relatively well.

15. nincompoop

true

16. anonymous

I guess what I'm saying is I'm overcomplicating it and it's been a while since I did this stuff so I gotta like rememorize a handful of pKas and stuff haha.

17. nincompoop

ya memorizing pKa is a pain

18. anonymous

Yeah don't tell anyone I only want to do chemistry and not be distracted by math. Ok so here's what I don't get: If Fluorine is so electronegative then won't it pull the electron density away from the carboxylic acid, therefore destabilizing the resonance structure meaning losing hydrogen is actually less favorable in this example @Bozhena

19. nincompoop

correct

20. nincompoop

here is what I think, the F's are quite far and not big enough to have that huge effect maybe I am dreaming haha I just woke up

21. nincompoop

I see why you put + in oxygen

22. nincompoop

their difference in electronegativity is very little 3.0 vs 3.5

23. anonymous

Yeah I have some stuff messed up in my brain, but then again this reminds me of that weird rule for stabilities of alkenes when it comes to the disubstituted ones I think. Actually I don't even remember what the exception was exactly, but something weird.

24. anonymous

Do either of you know what I'm talking about? (sorry on a side tangent here haha) Like something to do with cis/trans or EZ in their reactivities perhaps? not sure... I guess I just better grab my book since I can kinda remember what the page looked like.

25. nincompoop

it is time to crack our books open or perhaps ask king abb0t he knows this stuff like a pimp keeping track of H's

26. Photon336

@nincompoop klien... that's a really good book, I wish he were my prof for o-chem

27. anonymous

$$\color{blue}{\text{Originally Posted by}}$$ @nincompoop their difference in electronegativity is very little 3.0 vs 3.5 $$\color{blue}{\text{End of Quote}}$$ What did you mean by this, where did you find this and what are you referring to?

28. nincompoop

that would mean you need to be in John Hopkins University in Maryland, USA

29. nincompoop

I think it is in Maryland

30. nincompoop

ya he makes most of his money breaking down and doing simple reviews for orgo

31. nincompoop

on the right side

32. nincompoop

maybe I am thinking about something else hahaha

33. Rushwr

I agree @Bozhena