MEDICINAL CHEMISTRY MIDTERM 1

B

D

Look at the trends with electron donating groups and withdrawing

Largest (Most acidic) Ka = (C). A is the 4th ka

Alkoxy is electron withdrawing because resonance does not land negative charge. In the ortho position.

What about pka?

—> which ones the largest Pka? (A) and lowest? C.

Without looking at the charged state, we can look at the B/A ratio = 10^pH-pKa

Pka increase = ratio will change (B/A) decrease proportionally B% decrease and A% increase.

remember OH = 9-10

NH

B

Ka = (D1)(C2)(A3)(B4)

pka = (B1)(A2)(C3)(D4)

Least ionized (charged) =

COOH are pretty acidic in ibuprofen, aspirin, valorous acid. The reason why ciprofloxacin is least acidic is because that resonance structure with the nitrogen in aromatic ring can land a negative charge on the carbon. Ortho/para position with aromatic ring.

1. The double bond because it can have resonance structure for acid form. So it is number 1.

2. Three is not there because of withdrawing group.

Important!

NH by sulfonamide can lose its proton. Why not C?

What if pH = 2? Then it would be A.

C is the most lipophilic because of the aromatic ring. Can form weak hydrogen bond

D is very hydrophilic due to that electron acceptor i think he said idk

1

It is number #1.

Due to the double bonds with 4, the ring is much shorter so will not want to entirely give out electrons? I was thinking more of the resonance. It will not want to get a proton if it’s slaready sharing its lone pairs with the ring.

Acid-base pair, make me a pH = 8

Make me a buffer of pH = 8.

Circle most basic nitrogen atom (double bonds, aliphatic versus aromatic, etc)