Steam Distillation of an Essential Oil

Report

The lab report for this experiment consists of a lab write-up and lab notebook pages. Lab report guidance has been provided below. You will be submitting one file.

Please name your lab report file using the following format: Report 5_Student Number.pdf (replace Student Number with your own student number)

All lab reports are due Wednesday, December 8th, 2021 by 12 PM for all lab sections.

Instructions:

Prepare a PDF file that includes your report, the Carbon NMR activity, and your notebook pages. Reports will be submitted to Moodle. Your document should be double spaced, 12 pt font, and 7 pages or less including all figures (you will be penalized for exceeding 7 pages even if some of the pages are “partial pages”). The Carbon NMR activity and notebook pages do not count towards the 7 pages. All spectra should be page width. Your report should include the following sections: Abstract, Results & Discussion, Experimental, References, E-factor, Supporting Information.

Additional tips and guidance are provided below.

1. Address the following points in your Results & Discussion:

  • What was the main component of the clove oil? Support your choice by referencing your data (NMR and TLC). You should make reference to chemical shift values, J-values, and coupling patterns in your discussion as well as Rf values. Also locate a literature spectrum of your choice and compare your results.  If your NMR was not resolved or did not work, analyze the provided NMR file of commercial clove oil.
  • What percentage clove oil did you isolate from the crushed cloves following the steam distillation and liquid-liquid extraction?
  • What was the column efficiency of your flash dry column chromatography procedure?
  • Describe any anomalies in your data such as impurities in your NMR.
  • Provide a few sentences describing any sources of error or difficulties (e.g. emulsions, spilling your product, poor column recovery) that you had during your isolation of clove oil.

2. Within the Experimental section:

  • List all of the NMR signals produced by your compound. To assist with listing the NMR data, you can draw the molecule and label they hydrogens as HA, HB, HC, and so on. You can use the labels that appear in the figure for your assignments. For example, one signal’s assignment might read: 3.8 (2H, s, HA). You are expected to analyze two of the three complex splitting patterns displayed by the alkenyl protons. The third can be listed as a multiplet (m). If your data does not show the patterns clearly, use the supplemental data of commercial clove oil to complete the analysis.
  • Talkin’ chromatography (column + TLC). Do not list your fractions. Do not list the solvent mixtures used in each fraction. Do not list the colors of the fractions. Do not list which fractions you combined. Do not mention the rotovap. Do not attach your TLC plates. Do not attach drawings of your TLC plates. Chromatographic procedures are highly standardized so very little procedural detail is needed by the expert reader. A complete description of a dry column flash chromatographic separation requires only the name of the technique (“dry colu…”) and a list of the materials that you used (silica gel, solvents). A simple phrase like the following could be completely adequate for your Experimental section: “Dry column flash chromatographic purification (silica, hexanes-ethyl acetate 0-50%) of the crude product yielded compound name to be determined by you  (400 mg, 100% column efficiency): Rf (80:20 hexanes:ethyl acetate) 0.4; …”

2. For E-factor, make sure you include the quantities of silica gel and solvents used to purify your product. Estimate the quantity of silica gel used by assuming you used 30 mL (roughly filling the funnel half-way) and using the density of silica (or your best guess regarding its density) to convert volume into mass. Estimate the quantity of solvent by counting fractions, knowing the approximate volume of these fractions and their make-up.

3. Include the following figures in your Supporting Information section (you can always include more figures, but these four are required):

  • Proton NMR; full spectrum from 14 to -0.5 ppm (referenced to CDCl3)
  • Proton NMR; expansion from 7 to 4.9 ppm (peak picked, integrated)
  • Proton NMR; expansion from 4.15 to 3.15 ppm (peak picked, integrated)
  • Carbon NMR; full spectrum from about 200 to 0 ppm (referenced to CDCl3, peak picked)

4. Attach legible scans of your notebook pages (right-hand pages only) and the Carbon NMR activity.