Project #63574 - Ochem pre-lab

Example attatched (doesn't include the needed HNMR table). Lab procedure at the bottom.

You need the following, in this order:

  1. Title of experiment
  2. The reaction scheme for the specific reaction you are performing. No mechanism is included in the scheme. Underneath the structure of reactants write how much you are using, g or mg for solids, mL and density for liquids, also how many mmol of each you are using. Get this information from the procedure or online resources. Indicate in your scheme which reactant is limiting. Indicate in your scheme which product is the desired product and the theoretical yield in mmol and either g or mg.  Add above or below the arrow any solvents and conditions for the reaction. All the reactants should be to the left of the reaction arrow.
  3. Prepare a table of reactants and products and their pertinent information. Column headings are name, structure, MF, MW (g/mol), density (if a solid the say NA), amount used for reactants (g or mg for solids, mL for liquids), mmol used, mmol expected for products, theoretical yield for products g or mg and hazards. Each reactant and organic product is a row in the table.
  4. Prepare a table of reaction solvents and workup solutions. The columns for this table should be name, structure, bp, density, purpose (be specific i.e. “removes H2O”, “removes ions”, “neutralizes” etc.) and hazards. All of the information for 3 and 4 can be found in the procedure or online. Sigma-Aldrich Catalog is a good source. Chemfinder is another option.
  5. Obtain reference IR spectra for starting material and expected product. SDBS is a good source. You can also search online using the name along with the type of spectrum you are looking for. Organize IR data of the product(s) into table(s). For the IR table, the two column headings are structure and IR Diagnostic Bands (cm-1). The correct format for listing data in the second column is stretch, frequency range, descriptors. For example a broad,  medium sp3C-H stretch from 2800 -3000 cm-1would be: sp3C-H, 2800-3000, b, m.  You will be doing a full analysis of all non-fingerprint region bands of any acquired spectra.
  6. Obtain proton NMR spectra for the starting material and expected product. Organize the NMR information for the expected product into a table. You will need the structure of the product with the non equivalent H's labelled alphabetically. For each H set you will need chemical shift, multiplicity, J values if applicable and how many H are generating the signal. Each
  7. Draw out a formal curved arrow electron pushing mechanism for the reaction you are performing in the laboratory. You will need to show intermediates but not transition states.
  8. You can use chemical drawing software or copy and paste from a reference. If you have a reference be sure and cite it.  Save the entire pre lab as one document. Also save as a pdf file and upload the pdf file.

 Lab 9 Nitration of Toluene During Lab

Formation of the Electrophile.

NO2+, the electrophile in this reaction is formed from the reaction of sulfuric acid with nitric acid. Essentially the sulfuric acid dehydrates the nitric acid.

Reaction

1. Make an ice bath in an evaporating dish and place on a magnetic stirrer.  Clamp a 25 mL round bottom flask charged with a magnetic stir bar, so it is immersed in the ice water bath. Attach a clasien head and set up a condenser on the side arm.
2. Pour 1.0 mL of concentrated nitric acid into the vial. While stirring, slowly add 1.0 mL of concentrated sulfuric acid.
3. After the addition of sulfuric acid is complete, add 1.0 mL of toluene dropwise and slowly over a period of 5 minutes (slow down if you see boiling. Reaction produces a lot of heat).
4. While Stirring, allow the contents of the flask to reach the room temperature. Stir at room temperature for another 5 minutes.

Workup

1. Add 10 mL of water into a small separatory funnel. Then transfer the contents of the flask (from step 4) into the funnel. Rinse the contents with 4 mL of diethyl ether and add it to the separatory funnel. Repeat the ether rinsing one more time with a fresh 4 mL portion of ether.
2. Gently shake the contents of the separatory funnel, let settle, and remove the aqueous layer.
3. Wash the organic layer with a 10 mL portion of 10% sodium bicarbonate (shake and VENT due to the formation of gas), and finally, wash it with 5 mL of water. Wash with 10 mL of brine instead of drying with MgSO4. The brine will remove the water.
4. Discard the aqueous layer and add the organic layer to a tarred round bottom flask.
5. Remove the solvent on the rotovap. and obtain the isolated nitrotoluene.
6.  Calculate % yield. Obtain an IR spectrum of the product and prepare a proton NMR sample.

Subject Science
Due By (Pacific Time) 03/27/2015 12:00 am
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