Organic Chemistry
9th Edition
ISBN: 9781305080485
Author: John E. McMurry
Publisher: Cengage Learning
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Question
Chapter 20.SE, Problem 41AP
Interpretation Introduction
Interpretation:
The pKa of uric acid is 5.61. The percent dissociation of uric acid in urine at a pH=6.0 is to be calculated. Why uric acid is acidic even though it does not have a COOH group is to be explained.
Concept introduction:
The Henderson-Hasselbalch equation is
where, [A-] is the concentration of the dissociated uric acid and [HA] is the concentration of the undissociated uric acid.
A compound will be acidic and donate a proton, if the conjugate base obtained is stabilized by resonance.
To calculate:
The percent dissociation of uric acid in urine at a pH=6.0 if its pKa is 5.61 and to explain why uric acid is acidic even though it does not have a COOH group.
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Hydroxychloroquine (HQ) was used to treat coronavirus. The proposed mechanism for the action of HQ is to enter into the cytoplasm of the cell and increase intracellular pH from 4.7 to 6.3 and to stop the virus from entering the cell. Looking at the structure of HQ, and the fact that the intracellular pH is increased when HQ is present, how does HQ increase the pH?
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Hydroxychloroquine is a weak Bronsted acid.
The amino acid histidine has ionizable groups with pKa values of 1.8, 6.0, and 9.2, as shown.
COOH
H₂N-CH
|
CH ₂
pH =
CH
lonizable -COOH
group
COO-
H₂N-CH
1.8
pk₁
CH2
H
-COO-
CH
-HisH+
COO-
H₂N-CH
1
6.0
pk2
CH ₂
H
H N
-His
CH
-NH
COO-
H₂N-CH
1
9.2
pk₂
CH2
-NH₂
H
-N
CH
A biochemist makes up 80 mL of a 0.11 M solution of histidine at a pH of 5.1. She then adds 60 mL of 0.10 M HCl. What is
the pH of the resulting solution?
Given that C6H11COOH has a pKa = 4.8 and C6H11N + H3 has a pKa = 10.7, what pH would you make the water layer to cause both compounds to dissolve in it?
Chapter 20 Solutions
Organic Chemistry
Ch. 20.1 - Give IUPAC names for the following compounds:Ch. 20.1 - Draw structures corresponding to the following...Ch. 20.2 - Prob. 3PCh. 20.2 - The Ka for dichloroacetic acid is 3.32 Ă— 10-2....Ch. 20.3 - Calculate the percentages of dissociated and...Ch. 20.4 - Which would you expect to be a stronger acid, the...Ch. 20.4 - Dicarboxylic acids have two dissociation...Ch. 20.4 - The pKa of p-cyclopropylbenzoic acid is 4.45. Is...Ch. 20.4 - Prob. 9PCh. 20.5 - Prob. 10P
Ch. 20.6 - Prob. 11PCh. 20.6 - How might you carry out the following...Ch. 20.7 - Prob. 13PCh. 20.7 - Prob. 14PCh. 20.8 - Cyclopentanecarboxylic acid and...Ch. 20.8 - Prob. 16PCh. 20.SE - Prob. 17VCCh. 20.SE - Prob. 18VCCh. 20.SE - The following carboxylic acid can’t be prepared...Ch. 20.SE - Electrostatic potential maps of anisole and...Ch. 20.SE - Predict the product(s) and provide the mechanism...Ch. 20.SE - Predict the product(s) and provide the mechanism...Ch. 20.SE - Prob. 23MPCh. 20.SE - Predict the product(s) and provide the complete...Ch. 20.SE - Acid-catalyzed hydrolysis of a nitrile to give a...Ch. 20.SE - Prob. 26MPCh. 20.SE - Naturally occurring compounds called cyanogenic...Ch. 20.SE - 2-Bromo-6, 6-dimethylcyclohexanone gives 2,...Ch. 20.SE - Naturally occurring compounds called terpenoids,...Ch. 20.SE - In the Ritter reaction, an alkene reacts with a...Ch. 20.SE - Give IUPAC names for the following compounds:Ch. 20.SE - Prob. 32APCh. 20.SE - Prob. 33APCh. 20.SE - Prob. 34APCh. 20.SE - Prob. 35APCh. 20.SE - Prob. 36APCh. 20.SE - Prob. 37APCh. 20.SE - Prob. 38APCh. 20.SE - Calculate the Ka's for the following acids: (a)...Ch. 20.SE - Thioglycolic acid, HSCH2CO2H, a substance used in...Ch. 20.SE - Prob. 41APCh. 20.SE - Prob. 42APCh. 20.SE - How could you convert butanoic acid into the...Ch. 20.SE - How could you convert each of the following...Ch. 20.SE - How could you convert butanenitrile into the...Ch. 20.SE - How would you prepare the following compounds from...Ch. 20.SE - Prob. 47APCh. 20.SE - Using 13CO2 as your only source of labeled carbon,...Ch. 20.SE - Prob. 49APCh. 20.SE - Which method-Grignard carboxylation or nitrile...Ch. 20.SE - Prob. 51APCh. 20.SE - Prob. 52APCh. 20.SE - Propose a structure for a compound C6H12O2 that...Ch. 20.SE - Prob. 54APCh. 20.SE - How would you use NMR (either 13C or 1H) to...Ch. 20.SE - Prob. 56APCh. 20.SE - A chemist in need of 2,2-dimethylpentanoic acid...Ch. 20.SE - Prob. 58APCh. 20.SE - Prob. 59APCh. 20.SE - Prob. 60APCh. 20.SE - Prob. 61APCh. 20.SE - Prob. 62APCh. 20.SE - Prob. 63APCh. 20.SE - The following pKa values have been measured....Ch. 20.SE - Identify the missing reagents a-f in the following...Ch. 20.SE - Propose a structure for a compound, C4H7N, that...Ch. 20.SE - Prob. 67APCh. 20.SE - The 1H and 13C NMR spectra below belong to a...Ch. 20.SE - Propose structures for carboxylic acids that show...Ch. 20.SE - Carboxylic acids having a second carbonyl group...
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