3. Acids and Bases

Consider the following compounds that vary from nearly nonacidic to strongly acidic. Draw the conjugate bases of these compounds, and explain why the acidity increases so dramatically with substitution by nitro groups.

Would the following reactions go to the right or the left? Draw the products and label ALL species. Provide the full mechanism.

Rank the ions (⁻CH₃, ⁻NH₂, HO⁻, and F⁻) from most basic to least basic.

Rank the compounds in each set in order of increasing acid strength.

(a) CH₃CH₂COOH, CH₃CHBrCOOH, CH₃CBr₂COOH

A nitro group (–NO₂) effectively stabilizes a negative charge on an adjacent carbon atom through resonance:

Two of the following nitrophenols are much more acidic than phenol itself. The third compound is only slightly more acidic than phenol. Use resonance structures of the appropriate phenoxide ions to show why two of these anions should be unusually stable.

Tenormin, a member of the group of drugs known as beta-blockers, is used to treat high blood pressure and improve survival after a heart attack. It works by slowing down the heart to reduce its workload. Which atom in Tenormin is the most basic?

b. How does the presence of an electronegative substituent such as Cl affect the acidity of a carboxylic acid?

c. How does the location of the substituent affect the acidity of the carboxylic acid?

Compare the properties of propan-2-ol (I) and the hexafluoro analog (II).

(a) Compound II has almost triple the molecular weight of I, but II has a lower boiling point. Explain.

Explain why, when the guanidino group of arginine is protonated, the double-bonded nitrogen is the nitrogen that accepts the proton.

Rank the following alcohols from strongest to weakest acid.

CH₂═CHCH₂OH; CH₃CH₂CH₂OH; HC≡CCH₂OH

Predict the products (if any) of the following acid–base reactions.

(d) α-bromopropionic acid + sodium propionate

(e) benzoic acid + sodium phenoxide

Which of the following compounds is the most acidic?

Arrange the following compounds in order of increasing Brønsted acidity: $\mathrm{CH}{3}_3\mathrm{COH}$, $\mathrm{CH}{3}_3\mathrm{COOH}$, $\mathrm{CH}{3}_3\mathrm{CH}{2}_2\mathrm{COOH}$, $\mathrm{CH}{3}_3\mathrm{CH}{2}_2\mathrm{OH}$.

Given the following compounds: ${\mathrm{CH}3}_1\mathrm{COOH}$ (acetic acid), ${\mathrm{CH}3}_1\mathrm{OH}$ (methanol), and $H_{2}O$ (water), rank them in order of increasing acidity.