organic chemistry lab

Chem. 3011 Instructions on how to write your experimental section assignment (20 points) Last week you performed a column chromatography purification that yielded 3 compounds: aspirin, acetaminophen and caffeine. These compounds were analyzed by NMR, IR by the instructor and the data posted on D2L (you do not have mass spec data, but I still show them in the example). In your experimental section you will have to report a brief procedure of the column chromatography separation, for EACH compound, and their characterization. Please see the example below. I used a similar compound and procedure as an example. Ibuprofen is not one of your compounds and the method is different from what you used. Please also include the structure of each compound. Ibuprofen (1) Experimental IBUPROFEN (1). A commercially available over the counter medication, containing ibuprofen was purified by column chromatography. 5 g of silica gel were used as stationary phase. The solvent used for the column were A and B. A: 10% methanol in Dichloromethane and B: 20% methanol in dichloromethane. The method used for the column chromatography was as follows: 20 ml of A and 50 mL of B. Ibuprofen eluted in fraction 1 and 2. 350 mg of pure compound (white powder) were collected (75% yield) 1H NMR (300MHz, CDCl3,): δ 7.17 (d, 2H, ArH J=9Hz), 7.12 (d, 2H, ArH J=9Hz), 3.75 (q, 1H, CH- CH3), etc….. ESI-MS: m/z= found 207.2 (theoretical 207.13) IR (cm-1): 1780 (C=O) etc… List the significant peaks that are diagnostic and round the value to 1 cm-1 Assign the value to the functional group, for instance C=O

This is the general formatting:

• Chemical shift: 7.12 ppm

• Type of signal: s= singlet, d=doublet, t=triplet, q=

quadruplet, m=multiplet

• How many protons for this signal (based on

integration on the NMR spectra)

• Which type of protons : ArH (aromatic protons),

CHCH3 (If they are not aromatic you underline the H

you are referring to, especially if it is in an alkyl chain.

• When appropriate report J couplings (aromatic rings,

double bonds)

NMR assignment has to include the info about the NMR instrument (we used a 300 MHz and the solvent used)

Mass spec is reported including the ionization technique, that is ESI (electron spray ionization) in our case. List the major peaks you see and report them as m/z (mass over charge). The spectrum gives you value that are already m/z but you still want to indicate that in your characterization. In this example I just report the molecular ion, and I also report the theoretical value.