Spectroscopic Studies of 9, 10-dihydrobenzo(a)pyrene-7(8H)-one and 7, 8, 9, 10- tetrahydrobenzo(a)pyrene
Mireya Martinez*, Merlly Zavala, Kefa K. Onchoke (Advisor)
Department of Chemistry
Stephen F. Austin State University, TX 75962
Abstract
UV-vis
NMR
Infrared Spectrum
Polycyclic aromatic hydrocarbons (PAHs) are
organic molecules found in the environment. The
PAHs are formed from incomplete combustion, are
found in diesel exhaust particles, grilled foods, gas
burners, emission from wood, and cigarette
smoke. These compounds are known to be
carcinogenic and mutagenic1,2. Spectroscopic
studies were performed on two PAHs, 9,10dihydrobenzo(a) pyrene-7(8H)-one and 7,8,9,10tetrahydrobenzo(a)pyrene, which helped to
characterize them. Also, a theoretical infrared
study was done on 9,10-H2BaP, a scaling factor
was found for a simulated infrared spectrum.
These are the compiled UV-vis spectra of the two
compounds dissolved in different solvents. For both
compounds, the solvent, chloroform shifted the
spectrum more to the red(to the right). The bottom
right spectrum shows the compiled spectrum of the
two compounds dissolved in the same solvent.
Nuclear Magnetic Resonance (NMR) spectroscopy
helps in determining the structure of a compound
through many different 1-D/2-D techniques. Shown
below is the 13C spectrum for both compounds which
show the number of carbons present in the molecule.
Comparison of Frequencies
9, 10-dihydrobenzo(a)pyrene-7(8H)-one
0.9
Absorbance
0.5
10a
10
21
8
12c
12b
5a
20
250
300
350
400
Wavelength (nm)
450
18
1582.56
1487.56
1458.74
1457.80
1364.68
1337.39
1337.39
1230.57
1205.59
1205.96
1185.15
1161.59
1161.45
400 MHz CDCl3
500
Conclusions
7,8,9,10-tetrahydrobenzo(a)pyrene
0.800
Acetonitrile
0.600
Methylene Chloride
0.400
Methanol
0.200
Hexane
0.000
Ethanol
200
17
250
-0.200
300
350
400 MHz CDCl3
400
Wavelength (nm)
9,10-dihydrobenzo(a) pyrene-7(8H)-one (9,10-H2BaP)
28
These experiments helped characterize these
compounds with various spectroscopic techniques, so
that we can understand them more and how they
interact in the environment. The scaling factor was
found to be 0.98 for the simulated Infrared spectrum.
Chloroform
16
19
1583.94
Hexane
-0.1 200
3
3a
4
5
1614.86
1.200
15
6a
6
1597.17
Chloroform
2
10b
7
1597.82
Toluene
1.000
23
1629.77
Acetonitrile
0.3
1
12a
9
1709.62
Methylene Chloride
Absorbance
22
12
11
1682.36
Methanol
0.7
14
24
25
1744.51
13
27
26
Theoretical *0.98 (cm^-1)
Ethanol
0.1
Two Compounds Studied
Theoretical (cm^-1) Experimental
(cm^1)
Infrared Spectrum
13
Future Work
26
Using the density functional theory, a simulated
spectrum was created. A scaling factor was found so
that the experimental and the simulated spectra
overlaid more closely. The scaling factor of 0.98 was
used.
12a
24
25
11
22
12
Acetonitrile
14
1
2
10b
12c
10a
10
21
12b
3
3a
23
8
15
6a
7
5a
6
4
5
20
27
16
Absorbance
9
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
180
19
18
230
280
17
9,10-dihydrobenzo-7(8H)-one
3. Peterson, D. G.; Reichenberg, F.; Dahllof, I.; Environ.
Sci. Technol., 2008, 42(4), 1371-1376
4. Xue, J.; Liu, G.; Niu, Z.; Chou, C.; Qi, C.; Zheng, L.; &
Zhang, H. Energy and Fuels 2007, 21, p. 881-890
430
480
7,8,9,10-tetrahydrobenzo(a)pyrene
Acknowledgments
Comparison of Peak Shifts
References
2. Shapiro, R.; Ellis, S.; Hingerty, B. E.; Broyde, S., Chem.
Res. Toxicol., 1998, 11(4), 335-341
380
•Study of signaling pathways in cells on challenge
to PAHs
Wavelength (nm)
7,8,9,10-tetrahydrobenzo(a)pyrene (7,8,9,10-H4BaP)
1. Herreno-Saenz, D; Evans, F; Beland, F; Fu, P, Chem.
Res.Toxicol., 1995, 8(2), 269-277
330
•Chromatographic Studies of PAHs on the GC/MS
and the HPLC.
Solvents
9,10dihydrobenzo(a)pyre
ne-7(8H)-one
7,8,9,10tetrahydrobenzo(a)py
rene
Chloroform
λmax (nm)
Acetonitrile Hexane
λmax (nm)
λmax (nm)
317
316
309
330
327
325
346
343
342
317
315
315
333
328
329
349
345
346
•Department of Chemistry, SFASU
• Advisor: Dr. Kefa Onchoke
•Robert A. Welch Foundation (Grant No. AN-0008)