13c Nmr Spectrum

Moreover, the lack of chemical shift around 5.3 indicates the lack of double bonds. The NMR shows 7 peaks, which were labeled as a,b,c,d,e,f, and g respectively from low ppm to high ppm. Peak a and b appears to be similar to a methyl group with shifts between .9-1.4 ppm. Since peak b is more down field, it is assumed to be closer to the carbonyl. Since a carbonyl ketone have a chemical shift around 2.1, peak c, d, e are probably connected on one of the side chains.

The GC data for the product produced graph with a signal level out-of-range in peak. This gave a retention time 2.952 minutes. This would not indicate any of the possible ester products. However, after appropriate dilution, a retention time of 1.753 minutes was obtained. This retention time indicates that the ester product was ethyl benzoate.

Based on the 1H NMR spectrum that was collected, a few things can be determined. Based on deshielding and electronegativity, the peak that occurs around 4.7ppm is associated with the O-ethylsaccharin product and the peak at 3.8 ppm is associated with the N-ethylsaccharin product. Based on the height ration, the N-ethylsaccharin product is the more prevalent result.

Figure 2: Gas Chromatography analysis from the first sample. From top to bottom the peaks are ordered as followed: 3-methylcyclohexanol (A), 1-methylcyclohexanol (B), and 2-methylcyclohexanol

Through this experiment, I used IR and NMR to identify several unknown compounds. In order to identify my pure unknown compound, IR-12, I first looked for any medium to strong peaks on my IR spectra. The peaks that were useful in identifying my unknown were: a C-O bond of an ester at 1043.8, a C-O bond of an ester at 1243.6, a stretching C=O bond at 1743.2, a stretching alkyl C-H bond at 2860.4, and a stretching alkyl C-H bond at 2958.7. When figuring out which IR unknown was my compound, I first looked to see if my IR spectra showed an alcohol or an amine. Since my IR spectra didn’t show an alcohol or an amine, I was able narrow down my choices of possible compounds to twelve. Next, I looked for an aromatic ring in my IR spectra and since my IR didn’t show an aromatic ring, I was able to narrow down my choices to six possible compounds. Then I looked for any nitriles in my IR and since my IR didn’t contain any nitriles, I was able to narrow down my choice to five possible compounds. Then, I looked to see if my IR contained a ketone, an aldehyde, or an ester. My IR spectra didn’t contain a ketone or an aldehyde, however, it did contain an ester, which is how I was able to identify my unknown, IR-12.

There are four main regions of IR absorptions: region 4000 – 3000 cm-1 corresponds to N-H, C-H and O-H stretching, region 2250- 2100 cm-1 is triple-bond stretching , region 2000- 1500 cm-1 is double bonds and the region below 1500 cm-1 is the fingerprint region where a variety of single bonds are absorbed.3 The chromic acid test is a test for oxidizability and gives a positive result for primary and secondary alcohols as well as aldehydes2. A positive result in the chromic acid test is indicated by a color change and the formation of a precipitate. Tertiary alcohols give negative results for the chromic acid test since there must be a hydrogen present on the alcoholic carbon for oxidation to occur. The 2,4 DNP test, tests for a carbonyl and is therefore a dependable test for aldehydes and ketones. Finally, 13C NMR spectroscopy is a test to determine the structure of a compound. 13C NMR detects the 13C isotope of carbon. Each carbon has a different chemical shift. A carbon’s chemical shift is affected by the electronegativity of nearby atoms. Carbons that are bonded to highly electronegative atoms resonant downfield because the electronegative atom pulls electrons away from the nearby carbons and cause those carbons to resonant downfield1 (John McMurry, 2008). A general trend is that sp3-hybridized carbons absorb from 0 to 90 ppm, sp2-hybridized carbons resonant between 110

Koczanski, Krystyna; Xidos, James D. CHEM 1300 Laboratory Manual; UMSU Copy Centre: Winnipeg, MB, Canada, 2013, pp

This lab tested known substances against an unknown substance in order to determine the molecular makeup of the given unknown substance. The unknown substance benzaldehyde was determined by conducting six test followed by Proton NMR, C13 NMR and IR Spectroscopy reading. Test 52 D: 2,4-Dinitrophenylhydrazine, determined that the unknown product was a ketone and test 52 H: Acetyl Chloride indicates the presence of a secondary or primary amine.

An ester was synthesized during an organic reaction and identified by IR spectroscopy and boiling point. Acetic acid was added to 4-methyl-2-pentanol, which was catalyzed by sulfuric acid. This produced the desired ester and water. After the ester was isolated a percent yield of 55.1% was calculated from the 0.872 g of ester recovered. This quantitative error was most likely due to product getting stuck in the apparatus. The boiling point of the ester was 143° C, only one degree off from the theoretical boiling point of the ester 1,3-dimethylbutyl, 144 ° C. The values of the

The presence of anomeric proton signal at δ 6.03 (d, J = 3.3 Hz, 1H) indicated the existance of the furanose sugar. In 13C NMR spectrum, a high field methylene (confirm by DEPT) carbon signal at 36.6 and a quaternary carbon peak (C=N) at 154.6 conveyed the formation of the bridged isoxazoline moiety in 2.27a. The ESI-MS of the compound 2.27a showed the appropriate peak at m/z 412 (M+Na+) corresponding to its molecular formula C19H19NO8Na. The structure of 2.27a was further corroborated by 1H-1H COSY and NOESY experiments. However in the NOESY spectrum no co-relations were found between either bridgehead proton, or bridged methylene protons with other pre-existing carbohydrate chiral centers (Figure-2. 1).

The 1H NMR of the final product shows one proton that is more shielded than the protons present on the aromatic ring(s) seen as peaks at 6.5-8.5 ppm. Expected this shielded proton to bonded to the oxygen in the alcohol. Upon setting the integration of this proton to 1H knowing only one hydroxyl group is formed, integrated the protons at 6.5-8.5 ppm giving 12 protons present, which is three protons more than expected (Figure 5). Thus, 1H NMR suggests the

For the identification of the product, IR, 13C NMR and 1H NMR spectra were examined, and the product was found to be butyl propionate. In the IR spectrum, RM-11-Bi, five key peaks are observed. These peaks are sp3 hybridized carbons at 2961 cm-1 and 2877 cm-1, an ester at 1737 cm-1, a

The results from the NMR of 1-propanol showed 3 different prominent peaks with the peak at 2.2 cm-1 being the acetone. Because 1-bromopropane has three non-equivalent hydrogens it was found to represent this set of NMR data. The other product, 2-bromopropane only had 2 different types of hydrogens and would have only had 2 peaks. Further analysis of the structure of 1-bromopropane showed that the hydrogens closest the bromine group were an indication of peak A in the graph. Because of the electronegativity of the bromine, this peak was located further downfield. There were 2 neighboring hydrogens so using the n+1 rule gave the 3 peaks. Going down peak B showed the next carbon which had 5 neighboring hydrogens thus giving 6 peaks. Finally, the carbon furthest away from the bromine was found at peak C. It had 2 neighboring hydrogens and provided 3 peaks.

The purpose of this experiment was to identify one ketone with Thin Layer Chromatography and one using NMR spectrometry. We will do this by making 2, 4 a DNPH derivative and checking the melting points.

Firstly, NMR-based approach may lose some metabolites of interest if its protons are not detectable, or if its concentration is below detectable limits (Psychogios, Hau et al. 2011).Besides, the complexity of bio-fluid could generate a large number of peaks in NMR spectrum and potentially critical metabolites with low concentrations are often overlapped by large peaks, making it difficult for identification and quantification (Pan and Raftery 2007). Moreover, it is relatively insensitive in detecting volatile compounds. In Tampakopoulos’s study where NMR was applied to analyse the rumen composition profile, some volatile metabolites like acetaldehyde, pyruvic, malic, oxalacetic, acrylic and ß-hydroxybutyric acid could not be identified. Besides, the intensity of other important intermediate related to main VFAs, like succinic, fumaric and lactic acids are extremely low, which could lead to difficulties in quantification and unreliable results. Therefore, other analytical techniques should be applied, like GC-MS. GC–MS appears to have better sensitivity and lower detection limit than NMR spectroscopy, especially in analysing volatile compounds. Additional metabolites that were not identified by NMR could be quantified by GC in the study of human serum metabolome and vice versa (Psychogios, Hau et al. 2011), which suggests these two methods could serve as complementary