3. Acids and Bases

Which of the following carboxylic acids is the most acidic?

Given the following compounds: ${\mathrm{CH}}_3{3}_{3}N$ (trimethylamine), ${\mathrm{NH}}_3$ (ammonia), and ${\mathrm{CH}}_3{2}_2\mathrm{NH}$ (dimethylamine), rank them in order of increasing basicity.

Protonated cyclohexylamine has a Ka = 1 * 10-11. Using the same sequence of steps as in Problem 94, determine which is a stronger base: cyclohexylamine

or aniline.

e. Which has a greater Ka: cyclohexylammmonium ion or anilinium ion?

f. Which is a stronger acid: cyclohexylamine or aniline?

Which of the following four compounds is the most acidic (i.e., has the lowest $pKa$ value)?

Given the following compounds: $\mathrm{CH}{3}_2\mathrm{NH}$, $\mathrm{CH}{3}_{3}N$, $\mathrm{NH}{2}_2$, and $\mathrm{NH}3$, rank them in order of decreasing base strength (from strongest base to weakest base).

Identify the most stable conjugate base in each pair. Tell which structural features you analyzed and why you weighted them as you did in picking one answer.

(a)

Rank the following carbon-centered radicals in order of increasing stability: methyl radical (${\mathrm{CH}}_3\cdot$), primary radical (${\mathrm{CH}}_3{\mathrm{CH}}_2\cdot$), secondary radical (${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2\cdot$), and tertiary radical (${\mathrm{CH}}_3{C}_3\cdot$). Which sequence correctly orders them from least to most stable?

Given the following compounds: ${\mathrm{CH}}_3{\mathrm{COH}}_3$ (tert-butanol), ${\mathrm{CH}}_3{\mathrm{CHOH}}_2$ (isopropanol), and ${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}$ (ethanol), arrange them in order of decreasing $\mathrm{pK}a$ (highest $\mathrm{pK}a$ first).

Which of the following compounds is most acidic?

Given the following solutions: ${\mathrm{CH}}_3\mathrm{COOH}$ (acetic acid), $\mathrm{HCl}$ (hydrochloric acid), and $\mathrm{NH}{4}_{\mathrm{+}}$ (ammonium ion), rank them in order of increasing acidity.

Given the compound ${\mathrm{CH}}_3\mathrm{COOH}$ (acetic acid), identify the most acidic proton.

Given the following compounds: $\mathrm{CH}{3}_3\mathrm{COH}$ (tert-butanol), $\mathrm{CH}{3}_2\mathrm{CHOH}$ (isopropanol), and $\mathrm{CH}{3}_2\mathrm{CO}\mathrm{OH}$ (acetic acid), rank them in order of increasing acidity.

Imidazole is a heteroaromatic base. Which nitrogen, a or b, is most basic?

Given the following compounds with bolded hydrogens: (A) ${\mathrm{CH}}_3{\mathrm{CH}}_{2}OH$ (bold H on the OH), (B) ${\mathrm{CH}}_3\mathrm{COO}H$ (bold H on the COOH), and (C) ${\mathrm{CH}}_{3}NH{2}_{}$ (bold H on the NH$2_{}$), rank the bolded hydrogens in order of increasing acidity.

Explain the relative acidities.

CH₂═CHCH₂OH, CH₃CH₂CH₂OH, HC≡CCH₂OH