Dicarboxylic acids have two pKa's. For maleic acid (cis-2-butenedioic acid) these are pka¹ = 2.0, and pKå² = 6.3 For fumaric acid (trans-2-butenedioic acid) these are pK₂¹ = 3.0, and pk₂² = 4.5 Which factor best explains why the cis-isomer has a smaller pK₂¹ and a larger pK₂² than the trans-isomer? 2 a. Intramolecular dipole repulsion b. Intramolecular steric hindrance c. Selective solvation in water O d. Intramolecular hydrogen bonding

Dicarboxylic acids have two pKa's. For maleic acid (cis-2-butenedioic acid) these are pka¹ = 2.0, and pKå² = 6.3 For fumaric acid (trans-2-butenedioic acid) these are pK₂¹ = 3.0, and pk₂² = 4.5 Which factor best explains why the cis-isomer has a smaller pK₂¹ and a larger pK₂² than the trans-isomer? 2 a. Intramolecular dipole repulsion b. Intramolecular steric hindrance c. Selective solvation in water O d. Intramolecular hydrogen bonding

Organic Chemistry

9th Edition

ISBN:9781305080485

Author:John E. McMurry

Publisher:John E. McMurry

Chapter20: Carboxylic Acids And Nitriles

Section20.4: Substituent Effects On Acidity

Problem 7P: Dicarboxylic acids have two dissociation constants, one for the initial dissociation into a...

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How would the pKa values of carboxylicacids, alcohols, ammonium ions 1RNH32 + , phenol, and an anilinium ion 1C6H5NH32 + change if they were determined in a solvent less polar than water?
Most of the pKa values given in this text were determined in water. How would the pKa values of carboxylic acids, alcohols, ammonium ions (RN+H3) , phenol, and an anilinium ion (C6H5N+H3) + change if they were determined in a solvent less polar than water
Dicarboxylic acids have two pKa's.- For maleic acid (cis-2-butenedioic acid) these are pKa1 = 2.0, and pKa2 = 6.3- For fumaric acid (trans-2-butenedioic acid) these are pKa1 = 3.0, and pKa2 = 4.5 Which factor best explains why the cis-isomer has a smaller pKa1 and a larger pKa2 than the trans-isomer? a. Intramolecular hydrogen bonding b. Intramolecular steric hindrance c. Selective solvation in water d. Intramolecular dipole repulsion
The pKa values of the carboxylic acid groups of oxaloacetic acid are 2.22 and 3.98.a. Which carboxyl group is the stronger acid?b. The amount of hydrate present in an aqueous solution of oxaloacetic acid depends on the pH of the solution: 95% at pH 0, 81% at pH 1.3, 35% at pH3.1, 13% at pH 4.7, 6% at pH 6.7, and 6% at pH 12.7. Explain this pH dependence.
The pKa values of the carboxylic acid groups of oxaloacetic acid are 2.22 and 3.98. a. Which carboxyl group is the stronger acid? b. The amount of hydrate present in an aqueous solution of oxaloacetic acid depends on the pH of the solution: 95% at pH 0, 81% at pH 1.3, 35% at pH 3.1, 13% at pH 4.7, 6% at pH 6.7, and 6% at pH 12.7. Explain this pH dependence.
Provide an explanation without using the pka values : Why is phenol stronger acid than butanoic acid?
The isoelectric point (pl) of phenylalanine is pH 5.5. Draw the structure of the major form of glutamic acid at pH values of (a) 1 (b) 5.5 (c) 11.0.
What steps would you need to take to calculate the pKa1 and pKa2 of something? For example: hydrosulfuric acid H2S(aq) (-38.6 ΔH^0 f kJ mol^-1).
The pKa values of a few ortho-, meta-, and para-substituted benzoic acids are shown below: The relative pKa values depend on the substituent. For chloro-substituted benzoic acids, the ortho isomer is the most acidic and the para isomer is the least acidic; for nitro-substituted benzoic acids, the ortho isomer is the most acidic and the meta isomer is the least acidic; and for amino-substituted benzoic acids, the meta isomer is the most acidic and the ortho isomer is the least acidic. Explain these relative acidities. a. Cl: ortho > meta > para b. NO2: ortho > para > meta c. NH2: meta > para > ortho
The pKa values of a few ortho-, meta-, and para-substituted benzoic acids are shown below: The relative pKa values depend on the substituent. For chloro-substituted benzoic acids, the ortho isomer is the most acidic and the para isomer is the least acidic; for nitro-substituted benzoic acids, the ortho isomer is the most acidic and the meta isomer is the least acidic; and for amino-substituted benzoic acids, the meta isomer is the most acidic and the ortho isomer is the least acidic. Explain these relative acidities.a. Cl: ortho 7 meta 7 para b. NO2: ortho 7 para 7 meta c. NH2: meta 7 para 7 ortho
A typical amino acid with one amino group and one carboxylic acid group, such as serine can exist in water in several iconic forms. Suggest the forms of the amino acid at low pH and at a high pH. Amino acids generally have two pKa values, one in the range of 2 to 3 and the other in the range of 9 to 10. Serene, for example, has pKa values of 2.91 and 9.21. Using species such as acetic acid and ammonia as models, suggest the origin of the two pKa values. Glutamic acid is an amino acid that has three pKa’s: 2.10, 4.07, and 9.47. Draw the structure of glutamic acid and assign each pKa to the appropriate part of the molecule. An unknown amino acid is titrated with strong base, producing the following titration curve. Which amino acid are likely candidates for the unknown?
When BF3 behaves as a Lewis acid, the stability of the adducts with (CH3)2O, (CH3)2S, and (CH3)2Se decreases in the order in which the Lewis bases are listed. However, when the Lewis acid is B(CH3)3, the most stable adduct is that formed with (CH3)2S and the adducts with (CH3)2Se ad (CH3)2O are about equally stable. Explain the difference in stability of the adducts