Transcript TC09_obenchain.pptx

THE ROTATIONAL SPECTRA OF
PERFLUOROPROPIONIC ACID AND
ITS HYDRATES
WEI LIN, AGAPITO SERRATO III,
DANIEL A. OBENCHAIN, G.S. GRUBBS II
STEWART E. NOVICK, S.A. COOKE
TCO9
Perfluoroinated
carboxylic acids
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Experiment
•Wesleyan University chirped-pulse Fourier transform
microwave (SACI-FTMW) spectrometer. (TCO4-OBENCHAIN)
•Scan range between 8 and 14 GHz.
•Perfluoropropionic acid (97% Aldrich) in gas inlet line. (Drops
of DI water were added to the sample for the hydrate
measurements)
•Argon expansion gas at 0.6 atm backing pressure.
•Linewidths ~80 kHz fwhm.
•Line position error ± 8 kHz.
3
The SACI-FTMW Spectrometer at
Wesleyan University
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The gauche form of Perfluoropropionic Acid
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A portion of the spectrum of Perfluoropropionic
Acid. The enlarged section of the spectrum shows
several J = 5←4 transitions.
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Spectroscopic Constants of
Perfluoropropionic Acid
A /MHz
B /MHz
1893.5299(4)
1175.7031(4)
C /MHz
1118.2017(5)
J /kHz
0.245(4)
JK /kHz
0.40(2)
K /kHz
-0.44(1)
J /kHz
0.012(3)
K /kHz
-4.3(1)
N
83
/kHz
8
7
Comparison of the Rotational Constants of
Perfluoropropionic Acid
MP2/6Experimental MP2/aug
311G++(3df,3pd)
-pvdz
MP2/6311+G**
B3LYP/6311+G**
A (MHz)
1893.5299(4)
1857.9
1898.3
1883
1885
B (MHz)
1175.7031(4)
1166.3
1188.3
1178
1167
C (MHz)
1118.2017(5)
1107.3
1124.1
1129
1089
Paa(uǺ2)a
307.456
308.9
304.3
304.1
314.5
Pbb(uǺ2)a
144.501
147.6
145.3
143.5
149.6
Pcc(uǺ2)a
122.397
124.5
121.0
124.9
118.5
aThe
planar moment of inertia was calculated from Paa = (Ib +Ic – Ia)/2, Pbb = (Ia
+Ic – Ib)/2, and Pcc = (Ia +Ib - Ic)/2.
H. M. Badawi et al. , Can. J. analyt. Sci.
Spectrosc. 52 (2007) 252.
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The cis form of Perfluoropropionic Acid?
Predicted to be 24% population at room temperature
Not observed in the scan
“The Rotational Spectrum of Perfluoropropionic Acid”
G. S. Grubbs II, Agapito Serrato III, Daniel A. Obenchain, S.
A. Cooke , Stewart E. Novick, Wei Lin. J. Mol. Spectrosc.
2012, 275, 1-4.
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Predicted Structure of Monohydrate
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Experiment
•Wesleyan University chirped-pulse Fourier transform
microwave (SACI-FTMW) spectrometer.
•Scan range between 8 and 14 GHz.
•Perfluoropropionic acid (97% Aldrich) in gas inlet line. (Drops
of DI water were added to the sample for the hydrate
measurements, 1:1 ratio by volume)
•Argon expansion gas at 0.6 atm backing pressure.
•Linewidths ~80 kHz fwhm.
•Line position error ± 8 kHz.
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Spectrum Shows Signs of Doubling
505←404
524←423
523←422
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Preliminary Spectroscopic Constants of
Perfluoropropionic Acid Monohydrate
Experimental
ab initio
A /MHz
1693.14(9)
1634.0
B /MHz
876.00(3)
672.8
C /MHz
805.41(3)
619.3
J /kHz
0.3(1)
JK /kHz
-0.4(9)
K /kHz
-9(7)
J /kHz
-0.2(2)
K /kHz
-0.011(5)
N
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/kHz
113
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The monohydrate of 2,2,3,3tetrafluoropropionic Acid
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Preliminary Spectroscopic Constants of
Perfluoropropionic Acid Monohydrate
A /MHz
1693.14(9)
Predicted
OH···F
Structure
1630.4
B /MHz
876.00(3)
841.4
672.8
C /MHz
805.41(3)
783.4
619.3
J /kHz
0.3(1)
JK /kHz
-0.4(9)
K /kHz
-9(7)
J /kHz
-0.2(2)
K /kHz
-0.011(5)
N
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/kHz
113
Experimental
Predicted
OH···O
Structure
1634.0
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Fischer Esterification
H
O
R
C
O
O
O
OH
H
H
H
R
C
OH
R'
O
H
R
C
OH
R'
O
H
R
C
O
R'
R'
O
H
H
O
R
C
H
O
O
R'
H 3O
R
C
R 'O H 2 +
OH
O
H 2O
R
C
H
O
H
R'
O
R'
O
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New Hydrate Structure
δ-
δ+
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ab initio Structures
MP2/6311++G(2df,2pd)
2260 cm-1
0 cm-1
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Fischer Esterification
H
O
R
C
O
O
O
OH
H
H
H
R
C
OH
R'
O
H
R
C
OH
R'
O
H
R
C
O
R'
R'
O
H
H
O
R
C
H
O
O
R'
H 3O
R
C
R 'O H 2 +
OH
O
H 2O
R
C
H
O
H
R'
O
R'
O
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Possible Reaction Product
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Previous Works on Perfluorinated
Hydration Reactions
• Hexafluoroacetone will react readily with nucleophilic reagents. 1
O
F3 C
1Knunyants
H2O
CF3
HO
F3 C
OH
CF3
et. al. Izvetiya Akademii Hauk SSSR, 1961, (4), 684-692.
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Experimental Evidence for Reaction
• Monomer lines not present in both the H2O and D2O
scans
• Spectrum lost signal intensity much more rapidly
when water was added to sample in the argon line
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1,1,1-perfluoropropane triol
A /MHz
B /MHz
Predicted
1,1,1Experimental
perfluoropropane
triol
1576.8
1693.14(9)
929.0
876.00(3)
C /MHz
805.41(3)
J /kHz
0.3(1)
JK /kHz
-0.4(9)
K /kHz
-9(7)
J /kHz
-0.2(2)
K /kHz
N
-0.011(5)
/kHz
113
880.8
Predicted
OH···F
Structure
Predicted
OH···O
Structure
1630.4
1634.0
841.4
672.8
783.4
619.3
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Conclusions
• The rotational spectra of perfluoropropionic and the
monohydrate have been analyzed
• The experimental spectroscopic constants
compares well with ab initio calculation for the
monomer
• There are still questions about what the hydrate
structure could be
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Future Work
• Future works will look for isotopologues to further
confirm the proposed structures
• Dihydrates structures will also explored once the
monohydrate structure is determined
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Future Work
2,2,3,3 tetrafluoropropionic acid
2,3,3,3 tetrafluoropropionic acid
• Monomer structures have been assigned for both molecules
• Data is available for the hydrate structures, but no assignments
as of yet
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Acknowledgements
Olegario Vazquez Rana Faculty Fellowship, UT Brownsville
Welch Foundation
NSF CHE-1011214
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Group Members
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