microwave spectrum and ab initio calculations of meta-chlorobenzaldehyde sean arnold, jessica...
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MICROWAVE SPECTRUM AND AB INITIO
CALCULATIONS OF meta-
CHLOROBENZALDEHYDESean Arnold, Jessica Garrett, & Dr. Gordon BrownDepartment of Science and Mathematics Coker College 300 E College Ave. Hartsville, SC 29550RK15
Its Schiff base is known to have antifungal properties
Used in the synthesis of amino alcohols Common starting material in organic
synthesis
Applications of m-chlorobenzaldehyde
meta-chlorobenzaldehyde
trans-meta-chlorobenzaldehyde cis-meta-chlorobenzaldehyde
Coker CP-FTMW
240 MHz
240 MHz Chirped Pulsebefore power amplifier
Chirped Pulse
Fourier Transform
Double Sideband Measurement
165 12 174 13
20 2 3-1 3
51 5 41 4
v0 = 12300MHz white spectrum
v0 = 12304 MHzgold spectrum
For 20 2 3-1 3 :
12300 – 121.4 = 12178.6 MHz12304 – 125.4 = 12178.6 MHz
Coker CP-FTMW
Results:
Conditions: Nozzle heated to 150 degrees CelsiusBacking pressure set to 50 psi
10,000 signal averages (~40 hours measurement time)
Analysis using JB95 to help determine experimental rotational constants.
Results:
cis 35Cl cis 37Cl trans 35Cl trans 37Cl
A (MHz) 2345.808 ± 0.002
2327.419 ± 0.001
3172.65 ± 0.09
3153.90 ± 0.08
B (MHz) 959.439 ± 0.001
937.520 ± 0.002
813.009 ± 0.001
794.127 ± 0.002
C (MHz) 680.9698 ± 0.0008
668.3451 ± 0.0008
647.232 ± 0.001
634.478 ± 0.002
Xaa -37.38 ± 0.05 -30.58 ± 0.05 -52.1 ± 0.5 -42 ± 1
Xbb 4.2± 0.1 4.45 ± 0.09 18.5 ± 0.5 14.9 ± 0.8
Xcc 33.1836 26.1254 33.5820 27.0369
DJ 2 x10-5 ± 5 x10-6
1.4 x10-5 ± 9 x10-6
1.0 x10-5 ± 6 x10-6
7 x10-6 ± 4 x10-6
DJK — — — —
DK — — 4 x10-2 ± 2 x10-2
—
omc (MHz) 0.071 0.058 0.031 0.045
number of lines 210 126 72 56
Comparison to ab initio Conformation of
Chlorobenzaldhyde
Rotational Constants (MHz)
Constant RHF MP2 MO52X B3LYP Experimental
Trans-meta-chlorobenzaldehyde
(35Cl species)
A3201.5
873152.3
8123200.29
403163.36
423172.65±
0.09
B 818.4013
808.3755
815.6633
807.0433
813.009 ± 0.001
C 651.7888
643.3891
649.9976
642.9173
647.232 ± 0.001
Xaa -51.904
4-51.0553 -50.8394 -52.1 ± 0.5
Xbb 19.4222
17.8867 19.1574 18.5 ± 0.5
Xcc 32.4822
33.1686 31.6821 33.6
Cis-meta-chlorobenzaldehyde
(35Cl species)
A2376.4
6242328.2
9892355.90
002340.04
62345.808 ±
0.002
B 962.39351
955.1133
965.3409
951.0559
959.439 ± 0.001
C 685.2671
677.2800
684.7581
676.2217
680.9698 ± 0.0008
Xaa -36.916
1-37.072 -36.5835 -37.38 ± 0.05
Xbb 4.8991 4.1108 5.1432 4.2± 0.1
Xcc 32.0169
32.9612 31.4402 33.18
Measured 8-18.5 GHz spectrum of meta-chlorobenzaldehyde
Determined experimental rotational, distortion, and quadrupole coupling constants.
Compared constants to ab-initio calculations
Conclusions: trans-meta-
chlorobenzaldehydecis-meta-chlorobenzaldehyde
Acknowledgements
American Chemical Society-Petroleum Research Fund (PRF #50746-UN16)
Coker College
National Science Foundation (CHE-1213560)