Chemistry 351 - Principles of Organic Chemistry II
  Spring Semester 2018, Winona State University, Dr. Thomas Nalli

Guidelines for Lab Reports

Learning how to effectively report experimental results is extremely important in all of the sciences. Although the customary format may vary between discipline, a scientific report should be clear, thorough, concise and well organized and should make effective use of tables and graphs.

Formatting

  • Reports should be word-processed and double-spaced.
  • Do not ignore the need for subscripts and superscripts in chemical formulas. These are easily available in all modern word processors.
  • Use a minimum font size of 11 and left and right page margins of 1.0".
  • For chemical structures it is not acceptable to copy and paste graphics from web sources. There are a variety of free structure drawing programs available (see the Chem 351 Links page) and neatly hand-drawn structures are acceptable for the purposes of this course.

Conciseness - Strive to make your report as concise as possible. A page limit of 12 pages (not counting attachments) applies to all lab reports. (Please number the pages!)

  • In achieving conciseness, it is important that you use standard abbreviations and/or chemical formulas (when unambiguous) in place of full chemical names. For example write "MeOH" instead of "methanol", CDCl3 instead of chloroform-d, and C6H6 instead of benzene. (However, do not use formulas as stand-ins for names when the formula is complex enough to have many isomers possible, i.e. C9H8O2 is not an acceptable abbreviatioin for trans-cinnamic acid.)
  • All measurement units have standard abbreviations and these should always be used in conjunction with the numerical value for the measurement, e.g. always write "15 cm" not "15 centimeters" or "fifteen centimeters".
  • Here is a spreadsheet with commonly needed standard abbreviations. Remember to use these freely and to not waste space defining them.
  • Also consider creating your own abbreviations to replace long compound names. Most preferably use bold numbers (e.g., 1, 2, 3) to represent each compound. Define these simply by placing parentheses immediately after the first instance of the full compound name in the report. See example below:

"1,4-Di-tert-butyl-3-iodobenzene (1) was reacted with 4-tolylboronic acid (2) with the intent of forming the coupled product, 1,4-di-tert-butyl-4-tolylbenzene (3). The crude yield of 3 was 0.76 g (23% based on 1)."

Data Interpretation - Students are encouraged to bring rough drafts and questions about data interpretation to the instructor prior to submitting their final report.

Report Organization - Include all of the following sections.

Title Page - Give the number and title of the experiment, your names, course number and section, and the date submitted.

Purpose - Give specific information on the reaction being carried out including chemical equations showing structures of all reactants and products.
Mechanism - Present and discuss the accepted mechanism for the reaction carried out. Make sure to use equations/structures/curved arrows as necessary to show the mechanism properly.

Results Tables  Present all of the results of the experiment in table form. (The results tables can either be grouped all together in their own separate section or they can be interspersed where appropriate throughout the Results and Discussion.)
  • Table Organization and Style
      • Each results table should be completely self explanatory. In other words, it should be easily and fully comprehensible on its own even if viewed separately from the rest of the report.
      • Number and title the tables. The title should give fairly complete information about the data contained in the table. The number facilitates referring to the table in the Results and Discussion section.
      • Include structures of the compounds as part of the table title; immediately beneath the title place labeled structures that further clarify the contents of the table.
      • Strive to make tables very concise and "non-wordy". If at all possible keep each table confined to a single page. This well require a well thought out organization scheme for each title.
      • Make sure to observe the significant figures convention! Significant Figures Tutorial
      • Use footnotes as necessary to fill in missing details or to give definitions of abbreviations used in the table.
    • Table Contents
      • Yield data.
        • Include the absolute yield (mass), theoretical yield, and percent yield (rounded to the nearest whole number) of any product obtained. Do not include tare masses. (Show the calculation of theoretical and percent yield on an attachment not in the table.)
      • Physical Constants.
        • Melting points. Include the mp range for every crystalline solid product.
        • Other physical constants. These include refractive index and boiling point determinations.
          • Literature values. Include literature values for any physical constants measured. 
          • Units. Make sure to give units where required. (A well-organized table gives the units in the column headings or in the title rather than repeatedly throughout the table.)
      • Spectroscopic data. Use tables to summarize all spectroscopic data (NMR, IR, MS) obtained.
        • Peak data
          • IR. Round peak frequencies to the nearest 1 cm-1. Describe each peak as vs (very strong), s (strong), m (medium), w (weak)
          • MS. Round peak m/z values to the nearest whole number. List the approximate percent abundance of each peak (as compared to the base peak).
          • C-13 NMR. Round peak shifts to the nearest 0.1 ppm except when greater precision is needed to distinguish closely spaced peaks.
          • H-1 NMR. Round off peak shifts to the nearest 0.01 ppm. Make sure to also state the multiplicity and integration value of each peak.
        • Literature values.
          • Include literature values of chemical shifts, wave numbers, and m/z when available. Use a superscript number to cite the reference. (See the part on references below)
        • Peak assignments
          • For NMR the assignment should be a letter that refers to a labeled chemical structure included with the table.
          • For IR the assignment should refer to the specific type of bond vibration and the functional group family, e.g., C=O (ketone), C=O (anhydride), O-H (alcohol).
          • For MS, the assignment can take form of describing the neutral fragment lost, e.g. M - CH3, M - Br, or preferably show the structure of the cation detected
    • Results and Discussion
      • This section is referred to as "Results and Discussion" because the proper way to go about it is to state some results and then go on to discuss them.
      • Make sure to actually state the results to be discussed rather than just refer to a table. For example, even though your Table 1 might show the observed and literature mps for your product, your R&D part should start out as, "The mp of the product was found to be XX in comparison to the literature value of XX. (Table 1)"
      • After stating the results, go on to explain your interpretation as to how they align with the theory behind the experiment.
      • Make liberal use of structural diagrams, equations, curved arrows, images of molecular models, etc., to illustrate points being made as appropriate.
      • For puzzling results that do not seem to fit the theoretical expectations, are there valid explanations for them? Are they erroneous (due to systematic experimental error) (identify the specific reason for the systematic error if you think it is present). If you can rule out systematic error then examine how the theories could be modified to accommodate the results.
      • This section should include answers to the assigned questions. Make sure to explain all answers completely even if the question does not ask for an explanation. 
      • Above all, make sure your answers and interpretations make sense! Do not just take a stab at interpreting the results! If uncertain, do some Internet and/or library research or ask the instructor if you are on the right track.
      • For synthesis experiments always discuss:
        • Yield - Actual yield of product versus the theoretical yield (percent yields) and possible reasons for loss of yield. Please see this page for more info: Yield Reporting and Discussion
        • Spectra Interpretation - Evidence for the structure of the product from NMR, IR and/or chemical tests.
        • Purity - Purity of the product as indicated by mp, bp, NMR,  etc. Identify impurities that are present if possible, explaining thoroughly the reasoning behind your conclusions.
    • Conclusions
      • Reiterate the main points from your results and discussion sections in very brief form. Ideally, you can boil down the experiment to four or five main conclusions, each stated in one or two sentences.
      • Give actual data again in this section to support each conclusion. The data can be concisely included simply by providing it in parentheses at the appropriate places within the text.
      • Comment on whether the experiment was successful or not and feel free to make suggestions as to how the experiment could have been better designed or carried out.
      • Please notice that the title of this section is "Conclusions" not "Conclusion". It is not meant to to be a typical "wrap up" paragraph that starts out. "In conclusion, we carried out...etc". Instead it is a very concise list of the main points to be taken from the results obtained.
    • Experimental Section
      • This part describes the procedures that were used in very concise form. Use past tense, passive voice and list the results obtained in sentence form at the end of the paragraph. See any recent article in the Journal of Organic Chemistry for an example of how to write this part.
    • References
      • Give sources for all literature values as well as for any other background information.
      • List the references in the order they are cited in the report and give each reference its own number. Cite references in the main body of the report using superscripted numbers.
      • Use ACS style for your references list. See http://courses.chem.psu.edu/chem431/ManuscriptFiles/QuickRefGuide2.pdf
    • Attachments
      • Calculations - An example of each non-trivial calculation, including % and theoretical yield calculations, should be shown. Do not include trivial calculations such as subtraction of tare weights.
      • Spectra - Attach printouts of all spectra obtained. Make sure the spectra are completely labeled (name, date section number, expt number and title). Label all peaks on the NMR spectra. By labeling all solvent peaks and other expected extraneous peaks (e.g., TMS, water) you make clear what they are without unnecessarily devoting lab report discussion to them. For IR and Mass spectra it is not necessary to label small unidentifiable peaks especially those in the fingerprint region of the IR.

Product Submission - Products are ordinarily submitted for grading and then proper disposal. Submitted products should be fully labeled with the compound name and structure, your name, experiment number, and course number.

  • Solid products should be placed in small disposable vials (not conical vials!).
  • Liquid products should be placed in screw-top vials (not conical vials or reaction flasks).

Team Contribution Surveys (TCSs) - These are made available on D2L the same day the lab report is due for each experiment. They are due within one week of the lab report submission.