diff --git a/main.pdf b/main.pdf index a3634c2..dba3e4a 100644 Binary files a/main.pdf and b/main.pdf differ diff --git a/main.tex b/main.tex index c83d258..7444301 100644 --- a/main.tex +++ b/main.tex @@ -94,7 +94,7 @@ has simply been esterified differently than ASA.\\ \label{fig:methyl-salicylate} \end{figure} -Due to the similarity between the two molecules, ASA can be reacted to synthesize methyl salicylate~\cite{Hartel2009}. +Due to the similarity between the two molecules, ASA can be reacted to synthesize methyl salicylate~\cite{Hartel2009,nilered2017aspirin}. The purpose of this experiment was to convert acetylsalicylic acid obtained from commercial aspirin tablets into methyl salicylate through acid-catalyzed esterification in methanol under reflux conditions. @@ -173,6 +173,33 @@ The transformation encompasses two concurrent equilibrium-driven processes: To drive the reaction toward the methyl salicylate product, a substantial stoichiometric excess of methanol was employed, utilizing Le Chatelier's principle to overcome the reversible nature of the esterification. +\subsection{Kinetic and Thermodynamic Analysis} + +The transformation efficiency of the tandem hydrolysis--esterification is determined by the interplay between reaction rate and equilibrium position. + +\subsubsection{Thermal Activation and Collision Theory} +The reflux duration is required to provide the activation energy ($E_{a}$) necessary for the nucleophilic attack on the sterically hindered aryl ester. According to the Arrhenius relationship, the rate constant $k$ increases exponentially with temperature: +\begin{equation} + k = Ae^{-E_{a}/RT} +\end{equation} +Operating at the boiling point of the solvent increases the frequency of effective collisions and facilitates the formation of the required carbocation intermediates. + +Furthermore, by employing a vast molar excess of methanol, the system effectively follows pseudo-first-order kinetics. Under these conditions, the concentration of the alcohol remains negligible in its variation, and the rate depends solely on the concentration of the limiting aspirin precursor: +\begin{equation} + -\frac{d[\text{ASA}]}{dt} = k'[\text{ASA}] \implies [\text{ASA}]_{t} = [\text{ASA}]_{0}e^{-k't} +\end{equation} + +\subsubsection{Equilibrium Shifts and Chemical Potential} +As a reversible process, the yield is limited by the equilibrium constant ($K$). Because the esterification step is endothermic ($\Delta H^\circ > 0$), the application of heat shifts the equilibrium toward the products. This temperature dependence is quantified by the Van't Hoff equation: +\begin{equation} + \frac{d \ln K}{dT} = \frac{\Delta H^\circ}{RT^{2}} +\end{equation} + +The high reactant-to-substrate ratio further ensures that the reaction quotient ($Q$) remains lower than $K$ throughout the process. This maintains a negative Gibbs free energy ($\Delta G$), driving the reaction toward the formation of methyl salicylate: +\begin{equation} + \Delta G = \Delta G^\circ + RT \ln Q +\end{equation} +The combination of thermal input and stoichiometric bias effectively overcomes the reversible nature of the Fischer esterification. \subsection{Work-up and Purification} Following reflux, the reaction was quenched in ice-cold distilled water. Methyl salicylate ($\rho \approx 1.17$ g/mL) was isolated as the organic phase via liquid--liquid extraction. Residual acidic species (\ce{H2SO4}, \ce{CH3COOH}) were neutralized using saturated \ce{NaHCO3}: @@ -183,113 +210,9 @@ Following reflux, the reaction was quenched in ice-cold distilled water. Methyl The organic extract was dried over anhydrous \ce{MgSO4} and filtered to yield the pure essential oil. -\subsection{Outline} - -The document layout should follow the style of the journal concerned. Where -appropriate, sections and subsections should be added in the normal way. - -\subsection{References} - -References should be given in the normal way in \LaTeX{}. If you are using -\textsf{biblatex} (as recommended) then you can use the full range of citation -commands it provides. If you choose to use classical Bib\TeX{}, the -\textsf{natbib} package will be loaded and you can use it's commands. - -\subsection{Floats} - -New float types are set up in the preamble. The means graphics are included as -follows (Scheme~\ref{sch:example}). As illustrated, the float is ``here'' if -possible. -\begin{scheme} - \centering - Your scheme graphic would go here: PDF graphics are recommended. - %\includegraphics{graphic} - \caption{An example scheme} - \label{sch:example} -\end{scheme} - - - -The use of the different floating environments is not required, but it is -intended to make document preparation easier for authors. In general, you -should place your graphics where they make logical sense; the production -process will move them if needed. - -\subsection{Math} - -If packages such as \textsf{amsmath} are required, they should be loaded in the -preamble. However, the basic \LaTeX\ math(s) input should work correctly -without this. Some inline material $1 + 1 = 2$ followed by some display. \[ A = -\pi r^2 \] - -It is possible to label equations in the usual way (Eq.~\ref{eqn:example}). -\begin{equation} - \frac{\mathrm{d}}{\mathrm{d}x} \, r^2 = 2r \label{eqn:example} -\end{equation} -This can also be used to have equations containing graphical content. To align -the equation number with the middle of the graphic, rather than the bottom, a -minipage may be used. -\begin{equation} - \begin{minipage}[c]{0.80\linewidth} - \centering - As illustrated here, the width of \\ - the minipage needs to allow some \\ - space for the number to fit in to. - %\includegraphics{graphic} - \end{minipage} - \label{eqn:graphic} -\end{equation} \section{Experimental} -The usual experimental details should appear here. This could include a table, -which can be referenced as Table~\ref{tbl:example}. Notice that the caption is -positioned at the top of the table. -\begin{table} - \caption{An example table} - \label{tbl:example} - \centering - \begin{tabular}{ll} - \hline - Header one & Header two \\ - \hline - Entry one & Entry two \\ - Entry three & Entry four \\ - Entry five & Entry five \\ - Entry seven & Entry eight \\ - \hline - \end{tabular} -\end{table} - -Adding notes to tables can be complicated. Perhaps the easiest method is to -generate these using the basic \texttt{\textbackslash textsuperscript} and -\texttt{\textbackslash emph} macros, as illustrated (Table~\ref{tbl:notes}). -\begin{table} - \caption{A table with notes} - \label{tbl:notes} - \centering - \begin{tabular}{ll} - \hline - Header one & Header two \\ - \hline - Entry one\textsuperscript{\emph{a}} & Entry two \\ - Entry three\textsuperscript{\emph{b}} & Entry four \\ - \hline - \end{tabular} - - \textsuperscript{\emph{a}} Some text; - \textsuperscript{\emph{b}} Some more text. -\end{table} - -The example file also loads the optional \textsf{chemformula} and -\textsf{mhchem} packages, so that formulas are easy to input: -\texttt{\textbackslash ce\{H2SO4\}} gives \ce{H2SO4}. The two have similar -syntax but authors may prefer one or the other. - -The use of new commands should be limited to simple things which will not -interfere with the production process. For example, \texttt{\textbackslash -mycommand} has been defined in this example, to give italic, mono-spaced text: -\mycommand{some text}. \section*{Acknowledgements} diff --git a/references.bib b/references.bib index 13b1089..2437421 100644 --- a/references.bib +++ b/references.bib @@ -54,4 +54,15 @@ year = {2009}, month = Apr, pages = {475} +} + +@online{nilered2017aspirin, + author = {NileRed}, + title = {Turning aspirin pills into mint flavor}, + year = {2017}, + month = jul, + day = {17}, + organization = {YouTube}, + url = {https://www.youtube.com/watch?v=3NN9IUvrKi4}, + note = {YouTube video, 10.7M subscribers, 2,057,102 views, accessed 2026-05-12} } \ No newline at end of file