Project #65066 - organic chemistry prelab

Example attatched 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 10 Barbier Reaction During Lab

One goal of this course is for a student to be able to read an experimental section from a journal article and reproduce the experiment. This is actually harder than it looks. Consider the following journal-type experimental section "In a 50 mL round bottom flask charged with a stir bar, 5 mL saturated aqueous NH4Cl, 1 mL THF, 6.0 mmol zinc powder, 5.0 mmol benzaldehyde, and 5.0 mmol allyl bromide were stirred at room temperature under a condenser for 45 minutes. The mixture was diluted with 10 mL of (Et)2O and filtered to remove the insoluble material. The filtrate was then diluted with 10 mL of DI H2O and extracted with 15 mL of (Et)2O (×2). The ethereal phases were pooled, washed with 15 mL of brine, dried with MgSO4, and concentrated by rotary evaporation to obtain 0.67 g of clear oil (4.5 mmol, 90 % yield). The product was analyzed by ATR FTIR spectroscopy.
Compare our provided interpretation to the literature procedure.
1. Clean 50 mL and a 100 mL round bottom flasks and rinse them with acetone. The 100 mL round
bottom flask will be used later.

2. Add the following to the 50 mL round bottom flask:
     A) a magnetic stir bar
     B) 5 mL of aqueous saturated ammonium chloride solution
     C) 1 mL of THF
     D) 0.4 g of zinc powder (a curled up piece of weigh paper makes a good powder funnel)
     E) 0.500 mL of benzaldehyde (your TA will add this with an auto pipet)
     F) 0.470 mL of allyl bromide (your TA will also add this)
3. Attach a reflux condenser to the rb flask, hook up the water, and stir the reaction mixture at room temperature
for 45 minutes.
1. Add 10 mL of diethyl ether to the reaction mixture. Swirl well to ensure all organic components have contact with the ether so they can go into solution and be removed from the metal.

2. Gravity filter the mixture into a beaker. Make sure you top the stemless funnel with a watchglass to prevent your ether from evaporating. You will be saving the filtrate.

3. Transfer the filtrate into a separatory funnel. Add 10 mL of DI H2O and 15 mL of diethyl ether.  Shake well and vent. Repeat several times. Allow separation of the aqueous and organic layers. Drain the the aqueous layer into a beaker and then pour the organic layer into an Erlenmeyer flask.

4. Extract using 15 mL of ether  the aqueous solution a second time and combine the organic phases in the Erlenmeyer

5. Wash the organic solution with 15 mL of saturated sodium chloride aqueous solution and remove the aqueous phase.

6. Add MgSO4 to the ethereal solution and stir for 10 minutes. Make sure to keep a beaker or watchglass over the Erlenmeyer flask to prevent the ether from evaporating.

7. When the organic layer is dry, gravity filter it into a pre-weighed, dry, and clean 100 mL round bottom flask. Concentrate the product by rotary evaporation. Weigh the flask and determine the percent yield by mass difference. Obtain an IR spectrum of your product and
prepare a sample of your product for NMR analysis.

Subject Science
Due By (Pacific Time) 04/05/2015 12:00 pm
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