1. R. D. Suenram, Justin Lindsay Neill, Jason J. Pajski, Gordon G. Brown, Brooks H. Pate Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box 400319, Charlottesville, VA 22904 Michael Tubergen Department of Chemistry, Kent State University, Kent, Ohio 44242 BROADBAND ROTATIONAL SPECTRA OF THE HYDROXY BUTYRIC ACID SYSTEM

2. Gamma Hydroxybutyric Acid History of abuse since the 1980’s Originally thought to have anabolic effects to increase muscle mass In 2000 it became a Federally controlled substance and was designated a Schedule I depressant Active field of study by Forensic chemists

3. Gamma Hydroxybutyric Acid GC analysis is difficult because of high polarity and thermal instability. Thus conversion to derivatives is necessary –Gamma butyrolactone –Silyl derivatives

4. Hydroxybutyric Acids B-Hydroxybutyric acid G-butyrolactone G-Hydroxybutyric acid A-Hydroxybutyric acid

5. 11 GHz CP-FTMW Spectrometer Pulse Monitor 12 GHz Oscilloscope (40 Gs/s) Free Induction Decay 0.5– 11.5 GHz Arbitrary Waveform Generator Chirped Pulse Frequency Sweep 4 GS/s x8 7.5-18.5 GHz TWT Amplifier FID acquisition and Fourier transform 9.9 GHz PDRO 2 GHz Bandwidth Nozzle Sample Feed 18.99 GHz PDRO

6. AHB Conformer I

7. AHB Conformer II Spectrum

8. AHB Structures Gauche-1 Trans-1

9. Summary of AHB Results

10. BHB Spectrum

11. Gauche and Trans BHB

12. Summary of BHB Results

13. GHB and GBL Gamma Hydroxybutyric AcidGamma Butyrolactone

14. GBL Spectrum

15. GHB Survey

16. Ab Initio Conformers GHB E = 0 cm-1 E = 3 cm-1 E = 95 cm-1 E = 160 cm-1

17. GHB Conformers

18. Summary Hydroxybutyric acids have internal H-bond Hydroxyl H to carbonyl oxygen is preferred Theory and experiment agree - generally For the GHB system, the lactone is preferred for analysis because of stability and intense spectrum

19. Acknowledgements Funding: NSF Chemistry and MRI Program University of Virginia