MONITORING REACTION PRODUCTS USING CHIRPED-PULSE FOURIER

TRANSFORM MICROWAVE SPECTROSCOPY

Derek S. Frank, Daniel A. Obenchain, Wei Lin, Stewart E. Novick, S. A.

Cooke, G. S. Grubbs II

Allyl Phenyl Ether

- Claisen Rearrangement1

1. G. S. Grubbs II, S. A. Cooke, and Stewart E. Novick. The Chirped-pulse Fourier Transform Microwave (Cp-ftmw) Spectrum And Potential Energy Calculations For An Aromatic Claisen Rearrangement Molecule, Allyl Phenyl Ether. 67thSymposium on Molecular Spectroscopy, June 18-22, 2012, Columbus, OH.

FIT CONSTANTS

Conf 1 Conf 2 Conf 3

A (MHz) 1738.31180(84) 1414.0598(60) 4565.1124(26)

B (MHz) 676.51449(42) 459.55659(58) 629.14543(15)

C (MHz) 640.12176(39) 438.45758(55) 564.63169(15)

𝛥J (kHz) 0.0922(15) 0.05461(83) 0.01765(74)𝛥JK (kHz) 0.2849(78) 0.2710(43) -0.1244(75)𝛥K (kHz) 0.200(51) -25.85(23) 4.58(54)

δJ (kHz) -0.00924(73) 0.01135(95)

δK (kHz) -1.16(14) 0.42(11)

RMS (kHz) 4.91 4.29 4.43

N 68 41 61

Claisen Rearrangement?

Parameter Freq. (MHz)

A 4539.7

B 631.8

C 567.2

Parameter Value (MHz)

A 2511.4

B 1008.0

C 795.4

Conf 1 Conf 2 Conf 3A (MHz) 1738.31180(84) 1414.0598(60) 4565.1124(26)

B (MHz) 676.51449(42) 459.55659(58) 629.14543(15)

C (MHz) 640.12176(39) 438.45758(55) 564.63169(15)

Conf 1 Conf 2 Conf 3A (MHz) 1738.31180(84) 1414.0598(60) 4565.1124(26)

B (MHz) 676.51449(42) 459.55659(58) 629.14543(15)

C (MHz) 640.12176(39) 438.45758(55) 564.63169(15)

What are these molecules?

- Calculations ran at MP2/6-311G++(3d,2p) level1

1. Gaussian 09, Revision A.02, M. J. Frisch et al, Gaussian, Inc., Wallingford CT, 2009.

Perfluoropropionic Acid1

- Perfluorinated compounds are frequently used in industry for making polymers - Perfluoropropionic acid is water soluble, causing potential problems with contamination

1. G.S. Grubbs II, Agapito Serrato III, Daniel A. Obenchain, S.A. Cooke, Stewart E. Novick, Wei Lin, The rotational spectrum of perfluoropropionic acid, Journal of Molecular Spectroscopy, Volume 275, May–June 2012, Pages 1-4, ISSN

pKa = 0.38±0.10

1. http://www2.onu.edu/~b-myers/organic/2511_Files/pKa%20table.pdf2. 2. Scifinder; Chemical Abstracts Service: Columbus, OH, 2014; RN 422-64-0

(accessed Mar 31, 2014); calculated using Advanced Chemistry Development (ACD/Labs) Software V11.02 (© 1994-2014 ACD/Labs)

pKa of allyl hydrogen pKa ~ 30-40

Allyl Phenyl Ether Perfluoropropionic Acid2

• - Postulated mechanism• - All molecules have

dipole moments• - This is only one of

many possible reactions/complexes that could form

• - Will be verified by spectroscopy

1. 1. G. S. Grubbs II, R. A. Powoski, D. Jojola and S. A. Cooke. J. Phys. Chem. A 114(2010) 8009.

Chirped-Pulse FTMW experiment1

- One gas mixture enters the CHIRP, thus the reagents mix in the tube before being pulsed into the chamber - Reactions are occurring at room temperature in the tube in the liquid phase

- Sample spectrum generated from allyl phenyl ether and perfluoropropionic acid - Many distinct conformers found – perfluoropropionic acid lines were removed (see below) - Distortion as well as rotational constants were fit

APE PFPA2 Allyl Perfluoropropionate

Phenol3

A (MHz)

4539.7 1893.5299(4) 1412.4956 5650.46±0.20

B (MHz)

631.8 1175.7031(4) 466.10238 2619.20±0.20

C (MHz)

567.2 1118.2017(5) 432.02354 2619.20±0.20

CALCULATED/ CONSTANTS1

- MP2/6-311G++(3d,2p) basis set in Gaussian 09 - Previously studied molecules already have fits - No phenol lines found!

1. Gaussian 09, Revision A.1. Gaussian, Inc., Wallingford CT, 2009.2. Wei Lin, Agapito Serrato III, Daniel A. Obenchain, G.S. Grubbs II Stewart E. Novick, S.A. Cooke The Rotational Spectra Of Perfluoropropionic Acid And Its Hydrates. 67thSymposium On Molecular Spectroscopy, June 18-22, 2012, Columbus, OH.3. Kojima, Takeshi. "Potential Barrier of Phenol from its Microwave Spectrum." Journal of the Physical Society of Japan 15.2 (1960): 284-287.

APE PFPA Allyl Perfluoropropionate

Phenol Conf 3

A (MHz) 4565.1124(26) Published 1414.0598(60) Not found

1738.31180(84)

B (MHz) 629.14543(15) 459.55659(58) 676.51449(42)

C (MHz) 564.63169(15) 438.45758(55) 640.12176(39)𝛥J (kHz) 0.01765(74) 0.05461(83) 0.0922(15)𝛥JK (kHz) -0.1244(75) 0.2710(43) 0.2849(78)𝛥K (kHz) 4.58(54) -25.85(23) 0.200(51)

δJ (kHz) 0.01135(95) -0.00924(73)

δK (kHz) 0.42(11) -1.16(14)

RMS (kHz)

4.43 4.29 4.91

N 61 41 68

FIT CONSTANTS

Remaining Fit?

A (MHz) 1738.31180(84)

B (MHz) 676.51449(42)

C (MHz) 640.12176(39)

- Final conformer was assigned to the watercomplex with perfluoropropionic acid1

APE PFPA Allyl Perfluoropropionate

Phenol

A (MHz)

4565.1124(26)

1893.5299(4) 1414.0598(60) Not found

B (MHz)

629.14543(15)

1175.7031(4) 459.55659(58)

C (MHz)

564.63169(15)

1118.2017(5) 438.45758(55)

1. Wei Lin, Agapito Serrato III, Daniel A. Obenchain, G.S. Grubbs II, Stewart E. Novick, S.A. Cooke. The Rotational Spectra Of Perfluoropropionic Acid And Its Hydrates. 67th. Symposium On Molecular Spectroscopy, June 18-22, 2012, Columbus, OH.

Unanswered Questions: - What transitions are these? - What other reactions products were synthesized? - Can rotational spectroscopy be used as a tool to determine reaction products?

Future Possibilities - AutoFit - Other complexes - CHIRP contamination - Claisen rearrangement?

Other molecules tried - Yet to try -

Allyl Perfluoropropionate present from reaction in line

Conclusion

Acknowledgements

Microwave Spectroscopy Often Studies Structure

- H2-CuF, other metal halide complexes have been studied in the Novick lab1

- This is studied using ortho-para interactions- HOON has an O2 bond length of 1.9 Å- HOOH has a length of 1.48 Å, O2 has a bond

length of 1.2 Å

1. Frohman, Daniel J., et al. "Probing the Chemical Nature of Dihydrogen Complexation to Transition Metals, a Gas Phase Case Study: H2–CuF." Inorganic Chemistry 52.2 (2013): 816-822.2. Crabtree, Kyle N., et al. "Detection and Structure of HOON: Microwave Spectroscopy Reveals an O–O Bond Exceeding 1.9 Å." Science 342.6164 (2013): 1354-1357.3. Huber, Klaus-Peter, and Gerhard Herzberg. Constants of diatomic molecules. Springer US, 1979.4. Pauling, Linus. The nature of the chemical bond and the structure of molecules and crystals: an introduction to modern structural chemistry. Vol. 18. Cornell University Press, 1960.