91Ó°ÊÓ

(a) Lactic acid has a \(\mathrm{pK}_{\mathrm{a}}\) of \(3.9\). What is the [lactate]/[lactic acid] ratio at the \(\mathrm{pH}\) of blood (7.4)? (b) A \(0.1 M\) solution of lactic acid in water has a pH of \(2.5\). What is the [lactate] [lactic acid] ratio in this solution?

Many carboxylic acids are much better known by their common names than by their systematic names. Some of these follow. Provide a structural formula for each one on the basis of its systematic name. (a) 2-Hydroxypropanoic acid (better known as lactic acid, it is found in sour milk and is formed in the muscles during exercise) (b) 2-Hydroxy-2-phenylethanoic acid (also known as mandelic acid, it is obtained from plums, peaches, and other fruits) (c) Tetradecanoic acid (also known as myristic acid, it can be obtained from a variety of fats) (d) 10-Undecenoic acid (also called undecylenic acid, it is used, in combination with its zinc salt, to treat fungal infections such as athlete's foot)

Show by a series of equations how you could synthesize each of the following compounds from the indicated starting material and any necessary organic or inorganic reagents: (a) 2-Methylpropanoic acid from tert-butyl alcohol (b) 3-Methylbutanoic acid from tert-butyl alcohol (c) 3,3-Dimethylbutanoic acid from tert-butyl alcohol (d) \(\mathrm{HO}_{2} \mathrm{C}\left(\mathrm{CH}_{2}\right)_{5} \mathrm{CO}_{2} \mathrm{H}\) from \(\mathrm{HO}_{2} \mathrm{C}\left(\mathrm{CH}_{2}\right)_{3} \mathrm{CO}_{2} \mathrm{H}\) (e) 3-Phenyl-1-butanol from \(\mathrm{CH}_{3} \mathrm{CHCH}_{2} \mathrm{CN}\)(g) 2,4-Dimethylbenzoic acid from \(m\) -xylene (h) 4-Chloro-3-nitrobenzoic acid from \(p\) -chlorotoluene (i) (Z)-CH \(_{3} \mathrm{CH}=\mathrm{CHCO}_{2} \mathrm{H}\) from propyne

A certain carboxylic acid \(\left(\mathrm{C}_{14} \mathrm{H}_{26} \mathrm{O}_{2}\right)\), which can be isolated from whale blubber or sardine oil. yields nonanal and \(\mathrm{O}=\mathrm{CH}\left(\mathrm{CH}_{2}\right)_{3} \mathrm{CO}_{2} \mathrm{H}\) on ozonolysis. What is the structure of this acid?