TY - JOUR
T1 - Observation of Two Conformers of Acrylic Sulfuric Anhydride by Microwave Spectroscopy
AU - Smith, C. J.
AU - Huff, Anna K.
AU - Mackenzie, Rebecca B.
AU - Leopold, Kenneth R.
N1 - Funding Information:
This work was supported by the National Science Foundation (Grant Nos. CHE-1266320 and CHE-1563324) and the Minnesota Supercomputing Institute.
PY - 2017/11/30
Y1 - 2017/11/30
N2 - The rotational spectrum of acrylic sulfuric anhydride (CH2=CHCOOSO2OH, AcrSA) has been observed using pulsed-nozzle Fourier transform microwave spectroscopy. The species was produced from the reaction between acrylic acid and sulfur trioxide in a supersonic jet. Spectroscopic constants are reported for both the s-cis- and s-trans-AcrSA conformers of the parent and monodeuterated (OD) isotopologues. Geometries were optimized for both conformers using M06-2X/6-311++G(3df,3pd) methods. Single-point energy calculations at the M06-2X geometries were calculated using the CCSD(T)/complete basis set method with double and triple extrapolation [CBS(D-T)]. Further calculations indicate that the anhydride results from a π2 + π2 + σ2 cycloaddition reaction within the acrylic acid-SO3 complex. Because the C=O double bond of the acrylic acid migrates from one of the COOH oxygens to the other during the reaction, the s-cis form of acrylic acid leads to the s-trans form of the anhydride and vice versa. With zero-point energy corrections applied to the CCSD(T) energies, the s-cis and s-trans forms of CH2=CHCOOSO2OH are 19.0 and 18.8 kcal/mol lower in energy than that of SO3 + their corresponding CH2=CHCOOH precursor conformation. The zero-point-corrected transition state energies for formation of the s-trans and s-cis anhydrides are 0.22 and 0.33 kcal/mol lower than those of the complexes of SO3 with s-cis and s-trans acrylic acid, respectively, indicating that the reaction is essentially barrierless. This system adds to a growing body of examples demonstrating that carboxylic acids readily add to SO3 in the gas phase to produce the corresponding carboxylic sulfuric anhydride.
AB - The rotational spectrum of acrylic sulfuric anhydride (CH2=CHCOOSO2OH, AcrSA) has been observed using pulsed-nozzle Fourier transform microwave spectroscopy. The species was produced from the reaction between acrylic acid and sulfur trioxide in a supersonic jet. Spectroscopic constants are reported for both the s-cis- and s-trans-AcrSA conformers of the parent and monodeuterated (OD) isotopologues. Geometries were optimized for both conformers using M06-2X/6-311++G(3df,3pd) methods. Single-point energy calculations at the M06-2X geometries were calculated using the CCSD(T)/complete basis set method with double and triple extrapolation [CBS(D-T)]. Further calculations indicate that the anhydride results from a π2 + π2 + σ2 cycloaddition reaction within the acrylic acid-SO3 complex. Because the C=O double bond of the acrylic acid migrates from one of the COOH oxygens to the other during the reaction, the s-cis form of acrylic acid leads to the s-trans form of the anhydride and vice versa. With zero-point energy corrections applied to the CCSD(T) energies, the s-cis and s-trans forms of CH2=CHCOOSO2OH are 19.0 and 18.8 kcal/mol lower in energy than that of SO3 + their corresponding CH2=CHCOOH precursor conformation. The zero-point-corrected transition state energies for formation of the s-trans and s-cis anhydrides are 0.22 and 0.33 kcal/mol lower than those of the complexes of SO3 with s-cis and s-trans acrylic acid, respectively, indicating that the reaction is essentially barrierless. This system adds to a growing body of examples demonstrating that carboxylic acids readily add to SO3 in the gas phase to produce the corresponding carboxylic sulfuric anhydride.
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U2 - 10.1021/acs.jpca.7b09833
DO - 10.1021/acs.jpca.7b09833
M3 - Article
C2 - 29099599
AN - SCOPUS:85036640857
SN - 1089-5639
VL - 121
SP - 9074
EP - 9080
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 47
ER -