The unknown #35A has a melting point of 54°C, which is pretty close to the melting point value of 51°C in the literature (Pavia, Lampman, Kriz, & Engel, 2006). The solubility test indicated that the unknown #35A would an inert compound, which is also true as the result of the Beistein Test showed that a halogen atom being present (Table 1). The analysis of the 1H NMR data clearly shows that a benzene ring has to be present, which is para-substituted due to two multiplets with a chemical shift at around 7. 531 and 7. 778ppm.
The IR supports this suggestion as a peak is shown at 1597.0cm-1 for the benzene ring as well as a peak at 2907. 7cm-1 for the methyl group. There is also a peak at 3322. 8cm-1, which is most likely due to water in the sample (Table 2). The Tollens Test indicated the presence of a ketone, and the DNPH Test as well as Iodoform Test confirmed the presence of a methylketone in unknown #35A (Table 1). In order to determine the exact structure of unknown #35A, the mass spectra of the compound was analyzed and it seems obvious that one substituent has to be a halogen atom as the mas spectra shows an M+2 peak, which is of equal value (Table 3).
Thus, it has to be a bromine atom. The mass spectrum also shows a M+1-15 peak, which represents the methyl group, which was already identified in the NMR analysis. The mass spectra also shows the presence of a carbonyl group, which is part of the methyl ketone identified previously. Thus, unknown #35A is 4-bromo-acetophenone. Figure 16. Unknown #35A is 4-bromo-acetophenone. Unknown #35B The unknown #35B had a boiling point of 60°C, which is pretty close to the boiling point value of 63°C in the literature (Pavia, Lampman, Kriz, & Engel, 2006).
The solubility test indicated that the unknown #35B would be carboxylic acid. The analysis of the 1H NMR data clearly shows that two different methyl groups have to be present. A methyl group is presented by a doublet with a chemical shift at 0. 65ppm and the other CH3 group is presented by a multiplet with chemical shift of 0. 9465ppm (Table 8). The IR supports this suggestion as two peaks are shown at 2876. 5 and 2961. 4cm-1 for the methyl groups. There is also two peaks at 3385. 5 and 3359.1cm-1, which indicate a secondary amine (Table 6).
The HNO2 Test, however, indicated a primary amine (Table 5), and analysis of the mass spectrum supports this suggestion as the m/z is 73 (Figure 11), which is an odd number and can only explain an odd number of nitrogen atoms. In order to determine the exact structure of unknown #35B, the mass spectra of the compound was analyzed and the mass spectrum shows a M+1-15 peak, which represents the methyl group, which was already identified in the NMR analysis (Table 7).
The most prominent peak is at m/z =44, which presents a fragment with the molecular formula C2H6N, and another fragment at m/z=58, which has the molecular formula C3H8N. The results from the mass spectra analysis could also suggest N-methylisopropylamine or diethylamine but 2-aminobutane seems more accurate as the results from the NMR analysis shows different signals and the HNO2 Test indicates a primary amine. Thus, unknown #35B is 2-aminobutane. Figure 17. Unknown #35B is 2-aminobutane.
The unknown 35C had a melting point of 63°C, which is pretty close to the melting point value of 67°C in the literature (Pavia, Lampman, Kriz, & Engel, 2006). The solubility test indicated that the unknown #35C would be inert compound. The analysis of the 1H NMR data clearly shows that a benzene ring has to be present as the NMR data shows a multiplet at 7. 355ppm, which represents 10 hydrogen signals. The number of hydrogen signals would also explain two phenyl groups. The IR supports this suggestion as one peaks is shown at 1678. 0cm-1 for the benzene ring.
There is also a peak at 3335. 9cm-1, which indicates an OH group (Table 10). The Acetyle Chloride Test most likely indicated an alcohol, however, this test was not considered conclusive as it took a long time to actually see the positive result. The Lucas Test was performed instead in order to get conclusive test results. As expected, the Lucas Test showed also a positive test result, which indicated a secondary alcohol (Table 9). The analysis of the mass spectrum supports this suggestion as the molecular weight is m/z =184, which would explain two phenyl groups as substituents.
In order to determine the exact structure of unknown #35B, the mass spectra of the compound was analyzed and the mass spectrum shows peaks at m/z=77, 105, and 167, which represent the fragments shown in Table 11. The most prominent peak is at m/z =105, which presents a fragment with the molecular formula of C7H5O. As the NMR data only shows signals A-D as shown in Table 12, the unknown compound has to have two phenyl groups as substituents. Thus, unknown #35C is diphenylmethanol. Figure 18. Unknown #35C is diphenylmethanol. Conclusion Unknown #35A
The data obtained in this experiment was not conclusive to due to inconclusive chemical shifts in the NMR analysis; however, the results from the chemical tests and spectroscopic data are consistent with the data on 2-aminobutane in the literature. Unknown #35C A variety of tests were performed in order to determine the identity of unknown. Based on chemical classification tests and data from spectroscopy, it was possible to identify unknown #35C as diphenylmethanol. The data obtained in this experiment was conclusive and consistent with the data in the literature.
References
Mohrig, J. R. , Noring-Hammond, C. , & Schatz, P. F. (2010). Techniques in Organic Chemistry. New York, NY: W. H. Freeman and Company. Pavia, D. L. , Lampman, G. M. , Kriz, G. S. , & Engel, R. G. (2006). Introduction to Organic Laboratory Techniques; A Microsale approach. Belmont, CA: Thomson Brooks/Cole. Pavia, D. L. , Lampman, G. M. , Kriz, G. S. , & Vyvyan, J. K. (2008). Introduction to Spectroscopy. Belmont, CA: Thomson Brooks/Cole.