Nicotinic acid, more commonly named niacin, is one of the B vitamins. Show how nicotinic acid can be converted to (a) ethyl nicotinate and then to (b) nicotinamide.

Nicotinic acid, also known as niacin, has the following structure: \begin{align*} \text{Niacin (Nicotinic Acid)}: \hspace{5mm} \chemfig{*6(=-=(-(=[::+60]O)-[::-60](=[::-60]O)-[::+60]H)-=-=)} \end{align*} Notice the presence of a carboxylic acid group in the structure.

To convert nicotinic acid to ethyl nicotinate, we need to perform an esterification reaction. Here, the carboxylic acid group in nicotinic acid will react with ethanol - acting as a nucleophile - in the presence of an acid catalyst such as sulfuric acid (\(\ce{H2SO4}\)). The reaction is as follows: \begin{align*} \text{Nicotinic Acid + Ethanol} \xrightarrow{\ce{H2SO4}} \text{Ethyl Nicotinate + Water} \end{align*} \begin{align*} \chemfig{*6(=-=(-(=[::+60]O)-[::-60](=[::-60]O)-[::+60]H)-=-=)} + \chemfig{H_3C-[:-30]CH_2-OH} \xrightarrow{\ce{H2SO4}} \chemfig{*6(=-=(-(=[::+60]O)-[::-60](=[::-60]O)-[::+60](-[:-30]CH_2-CH_3))-=-=)} + \chemfig{H_2O} \end{align*}

Now, we will need to convert ethyl nicotinate to nicotinamide. We can achieve this by performing hydrolysis of ethyl nicotinate in the presence of a strong base, such as sodium hydroxide (\(\ce{NaOH}\)), followed by an acidification step: \begin{align*} \text{Ethyl Nicotinate + NaOH} \xrightarrow{1^\circ H_2O / |\Delta T} \text{Sod. Salt of Nicotinic Acid} + \text{Ethanol} \end{align*} \begin{align*} \chemfig{*6(=-=(-(=[::+60]O)-[::-60](=[::-60]O)-[::+60](-[:-30]CH_2-CH_3))-=-=)} + \chemfig{NaOH} \xrightarrow{1^{\circ} \ce{H2O}/\Delta T} \chemfig{*6(=-=(-([::+60]\chembelow{O}{^-})[::-60](=[::-60]O)-[::+60](-[:-30]Na))-=-=)} + \chemfig{H_3C-[:-30]CH_2-OH} \end{align*} The sodium salt of nicotinic acid can then be converted into nicotinamide using a reducing agent like lithium aluminum hydride (\(\ce{LiAlH4}\)): \begin{align*} \text{Sod. Salt of Nicotinic Acid + LiAlH4} \xrightarrow{\Delta T} \text{Nicotinamide} + \text{Byproducts} \end{align*} \begin{align*} \chemfig{*6(=-=(-([::+60]\chembelow{O}{^-})[::-60](=[::-60]O)-[::+60](-[:-30]Na))-=-=)} + \ce{LiAlH4} \xrightarrow{\Delta T} \chemfig{*6(=-=(-(=[::+60]O)-[::-60](=[::-60]O)-[::+60](-[^{120}](-[:60]H)-[:-60](=[-30]O)-[^{240}]H))-=-=)} + \text{Byproducts} \end{align*} This gives us the final product, nicotinamide.