chemsample-infraredspectroscopy-discussion


 * __Student A + B__**

//Unknown #7:// The IR graph that was discovered had certain peaks that we were able to identify to then help us determine the Unknown compound. The first peak we identified was at 3406.27cm-1, this told us that there was a secondary amine present. The next peak brought to our attention was the carbon-carbon strech in the range of 2938-2863cm-1. Finally we looked at the carbonyl peak at 1713.66cm-1. This carbonyl was a ketone, whose peak ranges from 1680-1750 on our table that we used. Unknown #7 was identified as N, N-dimethylacetamide.

//Diels-Alder:// The IR graph that we got for our Diels-Alder product had a very broad -OH stretch. This broad stretch was a sign of the very high concentration of salt present in our product. To get the salt out we used methylene chloride. The graph that we got from that also showed a very broad stretch and little peaks, we did not use that graph because we determined it insignificant. At 1637.93 cm-1 we identified that peak as an alkene.

//P-anisaldehyde:// This liquid was tested with the AgCl plates and came out to show many different peaks which shows it a purer substance than the product we obtained from Diels-alder. The peak at 2740.06 cm-1 showed us that there was an aldehyde present. Also, the peak at 1692.43 cm-1 showed the presence of the carbonyl group, which is part of the aldehyde. Lastly, the peak at 865cm-1 told us that is was para-disubstituted and this meant there was not only an aldehyde present, but another functional group was possibly present.

//Benzoic acid:// This graph had a very broad OH strech as well and there could be many reasons for this situation. The conclusion my partner and I came to was that there was moisture that was somehow exposed to the benzoic acid and KBr sample. This might have happened because we didn't cover the sample quickly enough after they were grinded togther to form a more fine powder for the IR spectrometer. Even though this was the case, we were still able to point out that it had an aromatic ring at the twin peaks starting from 1502cm-1 to 1602cm-1. Another discovery made was at the peak 1712cm-1 telling us that there was a carbonyl compound present.

//Unknown #2:// Unknown 2 was determined to be acetophenone. This is for one of two reasons: the first reason was the smell. It was the common smell of an aromatic compound. Also based off the IR graph, the peaks around 3,000 cm-1.

Student C + D
 * __IR Spectral Analysis ~__**

//Vanillin Spectra// ~ Our Vanillin sample displayed a strong characteristic -OH stretch (larger then expected though) in the 3000 - 3300 region. The 1650 region peak also gave us an indication that an aldehyde was present, along with -C=O stretch. This information can/does account for the carbonyl bound aldehyde shown in the chemical structure, however, it was difficult to identify a specific benzene ring region ... knowing the chemical structure though, has made it easier to defer several peaks as the origin of this ring.

//Acetophenone// ~ Given by a carbonyl bound ether group & connected to a benzene ring, both benzene (small double, or triple peaks high in the spectra) "peaks" & -C=O stretches were detected. Not to mention, alkane & alkene presences - given by their respective peaks &/or stretches. The spectra matches quite nicely with the known chemical structure!!!

//Unknown// //3//~ Peaks are identified within the Spectra itself, however, we have not yet formulated a reasonable chemical structure from the IR Spectra result. We've toyed with some ideas, but again, not knowing at least the chemical formula, it is difficult to determine an accurate chemical structure. We are hoping that H-NMR can give us better insight into narrowing down our ideas into a plausible structure!

//Unknown 12~//

//Diels Alder Product~//

Student E + F
 * __IR Spetroscopy Analysis__**

3000-2500 strong, very broad O-H bond These peaks showed us the hydroxyl bond present 1620-1680 Stretch Peak 685.44 showed us the possible presence of a C=C bond In comparing with other photos of IR seen from other groups and from other colleges I concluded that this is a good representation of an IR Spec for Benzoic Acid
 * __Benzoic Acid__**

2850-3000 strong C-H stretch 1670-1820 strong C=O stretch In looking at the strong peak (2985.22) there is a multitude of C-H bonds in the unknown. Also, peak 0.30 shows the presence of a carbonyl. In order for me get a more definitive structure for what unknown 11 is I would have to do an NMR.
 * __Unknown #11__**

In our previous experiment using the microwave unit MARS we found that our end product was contaminated with some unknown do to the high melting temperature of our product. This IR shows that it was most likely do to maleimide still being in the product. Peak 3185.38 shows that there is an N-H bond in our product which is in maleimide. Peak 703.42 shows the C=C bond present in 2,3-dimethyl-1,3-butadiene, which was our other reagent. In the fingerprint region you can see the peaks for the C-C bonds.
 * __Diers Alder Product__**

__**Ethylacetate**__

==== Peak 2985.44 tells us the presense of C-H bonds in our molecule. Peak 5.55 tells us that there is a O=C bond. ====


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