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)