chemsample-esterfication-discussion


 * __ General Discussion of Results ~ __**

__**Esterification ~ (Peach - Benyl Ethanoate / Benzylacetate)**__ //Conducted by: Student A + B//


 * [[image:Esterification_rxn.JPG]] ||
 * peach ||

The first major peak is around 3456.10cm-1. We called it the aromatic ring, this conclusion is based on the IR table from the link located in the link below, and, of course with the help of the known molecular structure (shown above). The aromatic peak is said to be around 3300cm-1. Another value we looked at peaked around 1740cm-1. This peak is the ester in the molecule. This had a literature value of 1750-1735cm-1.
 * IR**

[] : IR table

The Ester on our NMR table is located at 7.3ppm, this has hydrogen splitting because the hydrogen’s around the aromatic ring have two different signals due to the mono-substitution of the benzene ring. The signal around 5.5ppm is the ester. The chemical shifts are a little off, but this could be because the product is not proportional with the chloroform. The interval from 2.3-2.5ppm is the hydrogen’s on the ester. This has a literature value of 2.4ppm. There last peak is the one that is more shielded and is located around 1.3ppm, we decided based upon the table below that this was a terminal methyl group.
 * NMR**

[] :NMR table

__**Esterification ~ (Orange - Octyl ethanoate / octyl acetate)**__ //Conducted by: Student C//

Having a **Product weight (Yield)** of 2.6776 g yielded me some sort of insight into the efficiency of the reaction. When compared to other group yields, 2.6776 g was quite significant. Thus, it seems that my reaction process was efficiently run, and produced sound / reliable results. Therefore, I ran my sample through the protocols for IR, and NMR ... looking to confirm that what I had in my vial, was what I was supposed to have - Orange, Octyl acetate!

[|IR_spectra_-_Ester_product.JPG]
 * IR Spectra of Product ~**

Looking at the IR spectra, certain peaks are readily identifiable: - Alkane ... Range ( 2850 - 3000 cm -1 ) ... This peak can account for the long alkane chain present in the molecule, leading up to the single bonded Oxygen. - Carboxylic Acid / Esters ( 1750 cm -1 ) ... This peak can account for the (only) C=0 bond present in the molecule.


 * However**, other peaks (below 1600 - between 1200 and 1600) indicate that there exists the potential for other functional groups to be contained within this IR sample. Thus, it is possible that the sample is not completely pure.

[|Ester Prod - NMR spectra.bmp]
 * NMR Spectra of Product ~**

Looking at the NMR spectra, certain peaks and integrals have also yielded some insight into the products molecular structure (although, I feel that the spectra actually raises more questions, than it does answer): - Singlet / Duplet? @ 0.9 ... (1H) - Singlet @ 1.3 (6H, or 7H) - Singlet @ 2.0 (2H) - Triplet @ 4.1 (1H)

What this information tells me about this molecule, is ... not a whole lot, unfortunately. The integration, in particular, is somewhat baffling. For example: having a strong singlet with 6H, or 7H is difficult to interpret as accurate. Normally, a singlet at such a deshielded position in the field would indicate two identical methyl groups, however, the integration is not exactly reliable. This peak, along with the 0.9 ppm singlet, has given me the most trouble. Otherwise, the spectra is straight forward ... The singlet at 2.0 (2H) ppm is most likely a -CH2 group, with no surrounding hydrogens (probably flanked by a carbonyl), and, the triplet with (1H) is most likely an -OH group, isolated from the rest of the molecule. Again, however, my formulation of possible structures is limited, and I have not included one here (as I am not confident in any I have come up with).

__**Esterification ~ (Banana- Glacial acetic acid/ 3-methyl-1-butonal)**__ //Conducted by: Student D + E//

It is hard to know how effective our reaction was because we lost some product (from the organic layer) during the isolation process. So it is likely that we actually had a much higher yield than 44.7%. However, we did have the signature "banana" smell that we were hoping for, as well as the color of the expected product.

IR Using IR tables from the top of this page, we were able to make some determinations about our product. First off, we can say what it is NOT. There is no signature broad peak at 3500, which indicates hydroxyls. So we can safetly say that this is not an alcohol product. We also see the C-H bond stretch at 2850-3000. In determining if this was in fact an ester is a little bit more tricky. There is a peak at 1769, which is in the range for the C=O stretch of an ester. However, there is also a strong peal at 1700, which does not agree with the expected product. There would need to be further tests done to determine the purity of this product.

NMR The H-NMR for this product gave some helpful hints as to the product. The shifts were as follows:

multiplet 1.5 ppm (1-2H) doublet 1.0 ppm (3H) singlet 2.1 ppm (4H) triplet 4.2 ppm (1H)

It is hard to determine if the multiplet was intergrated correctly. It makes more sense in the structure of our expected product if the multiplet had on hydrogen. However, with these numbers all the H's are not being accounted for. I am not sure what this means in terms of the purity of our product. We would expect 5 signals based on the structure of the product. However, we only have four. This is excluding the singlet that is near 0, which I assumed to be the TMS reading.

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