1. ROTATIONAL SPECTROSCOPY OF THE METHYL GLYCIDATE-WATER COMPLEX
JASON GALL, JAVIX THOMAS, ZHIBO WANG,
WOLFGANG JÄGER, YUNJIE XU
Department of Chemistry, University of Alberta, Edmonton, AB, Canada
WG min 2:36 PM - 2:51 PM

2. Motivation-I
Methyl glycidate (MGly) is a chiral epoxy ester with multiple hydrogen-bonding sites.
MGly is a versatile chiral building block and is used in syntheses of many important organic molecules.
M. Seki, “A Practical Synthesis of a Key Chiral Drug Intermediate via Asymmetric Organocatalysis” Synlett 2008, 2, 0164.
3. Rotational spectra of MGly and its 13C were reported and two conformers identified.
J. Thomas, J. Yiu, J. Rebling, W. Jäger, Y. Xu, J. Phys. Chem. A, 2013, 117,

3. Motivation-II
4. MGly-H2O may exhibit interesting H-tunneling and methyl internal rotation tunneling motions.
W. Huang, J. Thomas, W. Jäger, Y. Xu, Phys. Chem. Chem. Phys. 2017, 19,
J. Thomas, O. Sukhorukov, W. Jäger, Y. Xu, Angew. Chem. Int. Ed. 2014, 53, 1156.
5. Provide connection to the chiroptical studies of chiral esters in solution.
It would be interesting to compare this system to other (chiral) molecule – water clusters studied.

4. Rotational spectroscopy with a cavity-based
and a chirped pulse FTMW spectrometer
Brown, Dian, Douglass, Geyer, Shipman, Pate, Rev. Sci. Inst. 2008, 79, ;
Dempster, Sukhorukov, Lei, Jäger, J. Chem. Phys. 2012, 137,
Thomas, Yiu, Rebling, Jäger, Xu, J. Phys. Chem. A. 2013, 117,
microwave cavity
nozzle
Resolution: 5 kHz
Bandwidth of each excitation: 500 kHz
Range: GHz
Resolution: 50 kHz
Bandwidth: 2 GHz; Range: GHz
A new chirped pulse FTMW spectrometer: GHz
N. Seifert, W. Jäger TH01
J. Thomas, Y. Xu
Balle, Flygare, Rev. Sci. Instrum. 1981, 52, 33; Xu, Jäger, J. Chem. Phys. 1997, 106, 7968.

5. Conformers of the MGly monomer
Exp: 60%:40%
13.7 kJ mol-1
MP2/ G(2d,p)
MGly MGly MGly MGly-4
ester oxygen
anti-MG syn-MG
K 57.4% % % %
J. Thomas, J. Yiu, J. Rebling, W. Jäger, and Y. Xu, J. Phys. Chem. A, 2013, 117,

6. MGly-W Conformers
ester oxygen
MP2/ G(2d,p)

7. Most stable MGly-W conformers
Parameter
MGly-1-W-I
MGly-2-W-II
MGly-2-W-III
MGly-1-W-IV
MGly-1-W-V
MGly-2-W-VI
∆De / kJ mol-1
1.85
3.32
3.02
2.75
3.25
∆De,BSSE / kJ mol-1
1.72
2.19
1.95
2.08
2.74
∆D0 / kJ mol-1
0.67
2.44
2.34
3.30
∆D0,BSSE / kJ mol-1
0.54
1.06
1.37
1.66
2.79
A / MHz
2908
2136
2035
3240
2629
4639
B / MHz
1251
1744
1533
1052
1306
935
C / MHz
938
1036
936
844
947
846
|μa| / D
3.73
0.37
1.73
1.26
3.62
0.86
|μb| / D
2.85
0.97
1.41
1.33
0.09
2.03
|μc| / D
0.60
0.44
1.07
1.45
1.61
0.12

8. MGly+water broadband scans

9. Methyl internal rotation barrier

10. Hyperfine splitting observed
a) JKa.Kc = 70,7 – 60,6
b) JKa.Kc = 51,4 – 41,3

11. Experimental spectroscopic constants
Ortho
Para
A/MHz
(10)a
(46)
B/MHz
(41)
(66)
C/MHz
(24)
(47)
ΔJ/kHz
0.5875(45)
0.5982(80)
ΔJK/kHz
-4.128(23)
-4.075(69)
ΔK/kHz
27.86(11)
27.21(90)
δJ/kHz
(27)
(41)
δK/kHz
0.0056(21)
0.0021(57)
ρ/MHz
13.60(11)
13.90(15)
β/MHz
425.9(34)
418.5(44)
γ/MHz
22.(29)
0.00(11)
V3/kJ mol-1
4.850(35)
4.788(46) Nb 44 25
NTc 83 50
σd/kHz
5.4
5.5
MGly-1
V3 =4.8672(95) kJ mol-1

12. H-tunneling splitting observed
OH motions in monofluoroethanol-water
Barrier-less after ZPE correction
Free OH up
Free OH down
minimum
transition state
1. Similar H-tunneling splitting observed in monofluoroethanol-water
H-tunneling splitting observed
W. Huang, J. Thomas, W. Jäger, Y. Xu, Phys. Chem. Chem. Phys. 2017, 19,

13. Comparison to the OH motions in methyl lactate-water
No H-tunneling splitting observed
J. Thomas, O. Sukhorukov, W. Jäger, Y. Xu, Angew. Chem. Int. Ed. 2014, 53, 1156.
Bond length in Å.
QTAIM
NCI
2.71
2.02
2.67

14. Conclusion
The monohydrate of methyl glycidate has been studied using rotational spectroscopy and ab initio calculations.
Splitting due to the methyl internal rotation has been observed and the associated barrier remains more or less the same as in the monomer.
Splitting due to the H-tunneling motion of H2O has also been detected and a possible tunneling path proposed.
Connection to solution measurement of methyl glycidate in water ?

15. Acknowledgements Thank you for your attention! Funding $$$:
International Mercator Fellowship with IRTG, Physics Department, Freiburg U. ,
Thank you for your attention!