The following abbreviations are used here: Discussion and Conclusions, D&C; limiting reagent, LR; theoretical yield, TY. (If you use abbreviations, please include a similar list in the report.) Note that chemical names are not capitalized (e.g., isopentyl acetate).
On the top of the first page, please write your name, the date(s) of the lab (that is: notthe date of writing or submitting the report), lab instructor’s name, your lab group (L1 or L9), and the title of the experiment. The title is: Lab 9 – Fischer Esterification of Acetic Acid with Isopentyl Alcohol.
Please keep this section short. The reaction mechanism, explanation of the experiment, and discussion of the results belong to the D&C section.
- a) Purpose of the experiment
Only a sentence about the objective of the lab
- b) Brief description of the experimental method
In the summary of the procedure (typically ≤10 sentences), mention the important techniques (e.g., heating under reflux, extraction) and briefly describe the apparatus used. Do NOT include any experimental details (e.g., 1.5 mL of). Use the past tense and passive voice.
- c) Your most important results
○ Percent yield for the isolated product
○ Brief note saying something like: the smell and the IR spectrum of the product showed that isopentyl acetate was formed
Reference the lab manual procedure, and include the bibliographical data of the lab manual (see bottom of pg. 16 of the manual). Please do NOT copy the standard protocol here, but describe any significant changes you made to it. For example, in many cases, the reflux time was less than that in the manual’s procedure. Also, we evaporated the solvent using a warm sand bath, instead of allowing evaporation at room temperature.
Show (1) the esterification reaction and (2) the neutralization of excess acetic acid (acetic acid + sodium bicarbonate = ?) during the workup procedure. The latter reaction can be typed using linear formulas (e.g., CH3CO2H).
- Data and Calculations
Please determine the limiting reagent (LR) first. Based on the volumes of the two starting materials, you should (1) present the detailed calculations for the mmol amounts of isopentyl alcohol and acetic acid, and (2) compare these mmol amounts. (You do not have to do such calculation for sulfuric acid. In the D/C section, explain why not.) The one with the least mmol amount will be the LR. Using this information, calculate the theoretical yield (TY) and the percent yield. All data needed for the calculations are shown in the lab manual. Please summarize your experimental and calculated data in a table. (Details like the mass of the culture tube and that of the culture tube plus your product are not needed.)
- Discussion and Conclusions (D&C)
You will not get more points for more words. If you address the relevant issues, the report should be OK. Please do NOT repeat the experimental procedure in this section.
- a) Discussion on the chemistry involved in the experiment
Please start with a brief discussion about the mechanism of the acid-catalyzed esterification reaction we used (Fischer esterification). All you have to do is explain the main steps of the reaction mechanism (e.g., protonation of carbonyl, tetrahedral intermediate). Illustration of the mechanism is OK, but not required. You can find guidance for this part in the lab manual, the prelab material, and several websites (e.g., references [1, 2]). You may also find the attached old prelab material useful. The last slide is a good summary of the reaction mechanism.
As discussed in lab, this esterification reaction is reversible. Its equilibrium constant (Keq) is not very high. What did we do to shift the equilibrium to favor the production of the ester? (References  and  provide tutorials about this subject.) Please briefly explain what the LR and TY are, and how they are determined (see references [3-5]).
- b) D&C concerning your results
Discuss your results (e.g., % yield, odor, and appearance of the product). Your conclusions should include assessment of your % yield (e.g., good/high [> 50%], moderate/fair [25% – 50%], low [< 25%]). If the % yield is not satisfactory, try to come up with reasonable explanation(s). Add a brief note saying something like: the odor and IR spectrum of the product indicated that the expected compound was isolated.
- c) Discussion of the sources of error
Even if your results were perfect, list the possible main sources of error in the experiment. You need several important causes of error.
- d) Interpretation of the IR data
Please discuss the IR spectra of acetic acid, isopentyl alcohol, and isopentyl acetate, which are posted on Blackboard. Do NOT include the spectra in the report. For each spectrum, you need only a TABLE including the wavenumber (cm-1), group or bond involved (e.g., O-H, C=O, CH3), and further information (e.g., stretching, bending) for each identified peak. For this task, you can study the Blackboard material and the information available on websites (e.g., references [6-8]). I will also discuss the spectra during my office hours. In the tables, specific wavenumber data read out from the IR spectra should be presented, instead of listing general ranges for the given signal types. In addition, please briefly describe the main differences between the spectra of the starting materials and the product, which indicate that a reaction has occurred.