ir-nmr-studenta




 * Figure 1. ** NMR spectrum of oxidation product: benzhydrol refluxed with CrO3 in Amberlite. Oxidation product is a mixture of benzhydrol and benzophenone.
 * Analysis: ** Upon comparison of my NMR spectrum to the spectra of benzhydrol and benzophenone from the SDBS database, it again seems as though benzyhdrol is the major component of my oxidation reaction. The singlet at about 7.2 ppm is representative of the hydrogens of the two aromatic rings in benzhydrol. The integral may, however, be slightly off since there should only be 10 hydrogens on these two rings. If my product were benzophenone, I would only have a multiplet representing the hydrogens on the aromatic rings. The two smaller peaks (at approximately 5.8 ppm and 2.4 ppm) are also seen on the SDBS NMR spectrum of benzhydrol. They are singlets each representing one hydrogen with no spin-spin splitting. The singlet at 5.8 ppm is representative of the hydrogen atom attached to the carbon in between the two aromatic rings. It is highly deshielded in the vinylic position. The singlet at 2.4 ppm represents the hydrogen bonded to the oxygen atom (O-H). If my oxidation product was benzophenone, I would have only seen the multiplet of the aromatic rings.




 * igure 2. ** NMR spectrum of benzyhdrdol from the SDBS Database (for comparison to oxidation product NMR).




 * igure 3. ** NMR spectrum of benzophenone from the SDBS Database (for comparison to oxidation product NMR).


 * Figure 4. ** NMR spectrum of a known compound: ethyl acetate. Note: I was told not to run my previous known compound (nitrobenzene from IR) since it is more difficult to read.
 * Analysis: ** The quartet at approximately 4.2 ppm represents the two -CH2 hydrogens next to the oxygen atom and the methyl group. The methyl group causes the splitting of these hydrogens, and the proximity to two electronegative oxygens from the ester and carbonyl cause the deshielding and downfield peak. The singlet at approximately 2.1 ppm represents the three hydrogens of the methyl group next to the carbonyl oxygen. There is no splitting of the signal since these three hydrogens have no hydrogen neighbors. The triplet at approximately 1.3 ppm represent the three hydrogens of the methyl group furthest to the right of the molecule in the structure pictured above. These hydrogens are split by the two neighboring hydrogens and are more shielded, so appear more upfield. The two signals at 4.2 ppm and 1.3 ppm are very representative of an ethyl group. The NMR from the SDBS database is very similar to the NMR reading from Northeastern.




 * Figure 5. ** NMR spectrum of ethyl acetate from SDBS Database for comparison.

benzyl alcohol Back to Data ad Results
 * Figure 6. ** NMR spectrum of unknown #7.
 * Analysis: ** This NMR spectrum shows that there are three different types of hydrogens present. The five hydrogens represented by the singlet at 7.3 ppm are characteristic of an aromatic ring. However, the singlet makes it seem as if all five of these hydrogens are identical. From the IR data, the ring is most likely mono-substituted. The substituent must not have a large splitting effect on hydrogens of the aromatic ring. The singlet at 4.8 ppm has two hydrogens. These hydrogens are fairly downfield, indicating they must be deshielded. Vinylic hydrogens often have signals around this range, making me think that a CH2 group may be attached to the aromatic ring. Based on the IR data, I know that an alcohol is present in my unknown. I was unsure if it was a phenol or primary alcohol based on the IR spectrum. The signal at 2.0 ppm makes me think that I have a primary alcohol. Also, the CH2 group is a singlet, so I know that it has no hydrogen neighbors to split the signal. Overall, my proposed structure is: