Ochem ?

[teefRcool]

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Hi guys i'm kinda lost in this problem i've been looking at it in one of my textbooks. Could someone help me out. Thanks here is it

A) meta-cyanophenol PKa=8.61
B) para-cyanophenol pKa=7.95

1) Whats the relationship between the pKa and acidity?
2) Which is the stronger acid A or B? This one i beleive is B if wrong please say so
3) What do the conjuage bases of these phenols look like?
4) what does the detailed stucture of the cyno group look like?
5) Describe the resonance forms of both conjugate bases
6) are the cyno groups involved in the resonance? if so how
7) what effect does resonance have on the relative acidity of A and B?

I'm a little lost thanks a lot if you could help.






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[gdbaby]

Hi guys i'm kinda lost in this problem i've been looking at it in one of my textbooks. Could someone help me out. Thanks here is it

A) meta-cyanophenol PKa=8.61
B) para-cyanophenol pKa=7.95

1) Whats the relationship between the pKa and acidity?
2) Which is the stronger acid A or B? This one i beleive is B if wrong please say so
3) What do the conjuage bases of these phenols look like?
4) what does the detailed stucture of the cyno group look like?
5) Describe the resonance forms of both conjugate bases
6) are the cyno groups involved in the resonance? if so how
7) what effect does resonance have on the relative acidity of A and B?

I'm a little lost thanks a lot if you could help.

I'll give it a shot.
1. pKa is the negative log of the Ka, which is the acid ionization constant. The smaller the pKa, the stronger the acid.

2. B is the stronger acid.

3. Do they want a picture? If so it would be the same molecule minus the H proton of the phenol.

4. the cyno group is a carbon-nitrogen triple bond. There is a lone pair on nitrogen with the carbon attached to the ring.

5. Boy. You have quite a few here. One would be to lone pairs on the oxygen with a double bond to the ring and two double bonds in the ring, but there are a few.

6. cyano groups are electron withdrawing so they oull electron density away from the ring and delocalize the anion in the conj base.

7. the more resonance structures, the more stable the molecule, the stronger the acid.