PROPANOIC ACID JAVIX THOMAS Department of Chemistry University of Alberta Edmonton AB Canada MICHAEL J CARRILLO AGAPITO SERRATO III Department of Chemistry University of Texas Rio Grande Valley ID: 627663
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CONFORMATIONAL ANALYSIS OF 3,3,3-TRIFLUORO-2-(TRIFLUOROMETHYL) PROPANOIC ACID
JAVIX THOMAS, Department of Chemistry, University of Alberta, Edmonton, AB, Canada; MICHAEL J CARRILLO, AGAPITO SERRATO III, Department of Chemistry, University of Texas Rio Grande Valley, Brownsville, TX, USA; ELIJAH G SCHNITZLER, WOLFGANG JÄGER, YUNJIE XU, Department of Chemistry, University of Alberta, Edmonton, AB, Canada; WEI LIN, Department of Chemistry, University of Texas Rio Grande Valley, Brownsville, TX, USA.72nd International Symposium on Molecular Spectroscopy, 6/20/2017Slide2
Trifluoroacetic acidS. Antolinez
, J.L. Alonso, H. Dreizler, E. Hentrop, D.H. Sutter; Z. Naturforsch. 54a, 524, (1999) B. Ouyang, T.G. Starkey, B.J. Howard; J. Phys. Chem. A., 111, 6165 (2007)Perfluoropropanoic acidG.S. Grubbs II, A. Serrato III, D. A. Obenchain, S.A. Cooke, S.E. Novick, W. Lin; J. Mol. Spec., 275, 1(2012).Perfluorobutyric acid J. Thomas, A. Serrato III, W Lin, W. Jäger, Y. Xu; Chem. Eur. J., 20, 6148, (2014)Perfluoropentanoic acidA.M. Pejlovas, W. Lin, S.G. Kukolich; Chem. Phys. Lett., 143, 124311 (2015)
Only one
lower energy conformer detected for
perfluorocarboxylic
acids Slide3
Comparison of the most stable conformers of the three short chain PFCAs, i.e.
trifluoroacetic acid (left), perfluoropropionic acid (middle), and PFBA (right).Slide4
A potential energy scan
of perfluorobutyric acid by rotating carboxyl group about the C1-C2 bondSlide5
Difluoroacetic
acidB.P. van Eijck, A.A.J. Maagdenberg, G. Janssen, T.J. van Goethem-Wiersma;J. Mol. Spec., 98, 282 (1983)2 conformers observed Fluoroacetic acidB.P. van Eijck, P. Brandts, P.M. Maas; J. Mol. Strc., 44, 1 (1978)B.P. van Eijck, G. Van der Plaats, P.H. Van Roon;J. Mol. Spec., 11, 67 (1971)2 conformers observed 2,3,3,3-tetrafluoropropanoic acidLin et al. Investigation ongoing3 conformers observed 3,3,3-trifluoropropanoic acidL. Evangelisti, J. van Wijngaarden; J. Mol. Spec., 290, 1 (2013)One lower energy conformer4,4,4-trifluorobutyric acidYoon Jeong Choi, Alex Treviño, Susanna L. Stephens, Stephen A. Cooke, Stewart E. Novick, Wei Lin; WD04One lower energy conformerSlide6
3,3,3-trifluoro-2-(trifluoromethyl)
propanoic acid (TTPA)Slide7
The m
icrowave spectrometers @EdmontonChirped-pulse FTMW spectrometerCavity based FTMW spectrometerSlide8
The Chirped-pulse FTMW
spectrometer@EdmontonSlide9
Experiment
University of Edmonton chirped pulse and cavity based Fourier transform microwave spectrometers;TTPA(97% Sigma Aldrich) in gas inlet;Trace amount of TTPA in expansion gas of 3 bar Helium (chirped pulse) and 2 bar Neon (cavity based).Slide10
Theory
Gaussian 09 program package dihedral angle τ(O12-C5-C2-C1) scan at B3LYP/6-311G level;Structure optimizations at B3LYP/aug-cc-pVTZ level and MP2/aug-cc-pVTZ level.Slide11
Potential energy scan along the dihedral angle τ(O12-C
5-C2-C1) in steps of 10° The calculations were done at the B3LYP/6-311G level.Slide12
Geometries of the four TTPA conformers identified computationallySlide13
TTPA-I
TTPA-IITTPA-IIITTPA-IVParametersB3LYP
MP2
B3LYP
MP2
B3LYP
MP2
B3LYP
MP2
Δ
D
(kJ/
mol
)
0
0
0.48
0.42
14.3
13.9
23.5
23.0
Δ
D
0
(kJ/mol)
0
0
0.36
0.27
13.6
13.6
22.9
22.6
A
(MHz)
1063.6
1078.1
1073.5
1087.8
1074.5
1087.5
1129.1
1146.6
B
(MHz)
963.0
977.1
962.7
977.2
965.4979.7952.6967.4C (MHz)680.5692.6684.9696.6688.1699.2656.9670.5µa (Debye)0.00.00.00.00.00.02.01.8µb (Debye)1.91.81.01.01.92.01.21.3µc (Debye)2.22.10.60.50.70.62.82.8
Calculated relative dissociation
energies and
spectroscopic
constantsSlide14
A sample spectrum showing the
440-331 transition of TTPAI and 441-331 transition of TTPA II from the cavity based measurement. Slide15
Experimental spectroscopic constants
ParameterTTPA-ITTPA-IIA (MHz)1075.53107(56)1085.63313(37)B (MHz)
975.17899(41)
975.16102(34)
C
(MHz)
688.28340(34)
692.86057(21)
Δ
J
(kHz)
0.0359(73)
0.0396(60)
Δ
JK
(kHz)
0.730(31)
0.402(23)
Δ
K
(kHz)
-0.724(21)
-0.394 (16)
δ
J
(kHz)
0.0114(26)
0.0131(27)
δ
K
(kHz)
0.029(10)
-0.0385(79)
N
37
36
σ
(kHz)
2.8
1.7Slide16
Conclusion
The rotational spectrum of TTPA was measured for the first time using both chirped-pulse and cavity-based FTMW spectrometers. Two conformers were observed experimentally and identified unambiguously. The rotational constants of the observed conformers are in excellent agreement with those from the quantum chemical structures. Comparison of TTPA and previously reported fluorinated carboxylic acids shows some noticeable differences in their preferred geometries and conformational energetics, such as the interconversion barrier height between the conformers, highlighting the diversity of conformational landscapes in this class of compounds.Slide17Slide18
Acknowledgement
Welch Foundation # BX-0048UTRGV Undergraduate Research Initiative (URI) The University of Alberta The Natural Sciences and Engineering Research Council (NSERC) of CanadaYX and WJ are holders of Tier I Canada Research Chairs.Texas Advanced Computing Center (TACC) and the Shared Hierarchical Academic Research Computing Network (SHARCNET: www.sharcnet.ca), the Western Canada Research Grid (Westgrid), and Compute/Calcul Canada.