This document summarizes an experiment that measured the yields of stabilized Criegee intermediates (sCIs) produced from the ozonolysis of trans-2-butene and 2,3-dimethyl-2-butene. The experiment used cavity ring-down spectroscopy to monitor the reaction of sCIs with SO2, allowing the sCI yields to be determined from changes in SO2 and O3 levels. The nascent sCI yields were found to be 0 for trans-2-butene and 0.15 for 2,3-dimethyl-2-butene.

1. Low pressure yields of stabilized
Criegee intermediates
produced from ozonolysis of
trans-2-butene and
2,3-dimethyl-2-butene
Mixtli Campos-Pineda, Jingsong Zhang
PHYS 174
ACS, Fall 2016

2. Outline
Motivation
Ozonolysis
Criegee intermediates (CIs)
Measuring the yields of CIs
Experimental Setup
CRDS
Analysis of spectra
Results
Scavenging with SO2
trans-2-butene ozonolysis: CH3CHOO
2,3-dimethyl-2-butene ozonolysis: (CH3)2COO
Summary

3. Motivation
One of the most important reaction pathways of Volatile
Organic Carbons (VOCs) in the atmosphere is oxidation.
One of the main oxidation reactions of unsaturated VOCs is
ozonolysis.

4. O 2
R, alkyl radical
RH, hydrocarbon
HONO +hn OH
OH
NO
RO 2
RO
HO2
NO 2
ROONO 2
RONO 2
RO 2
carbonyl
+
alcohol
ROOH
NO 2
O3
O2
hn
OH
Alkenes
OH production
mechanism in
alkene + O3 reactions

5. Carbonyl oxides, also know as Criegee Intermediates
(CIs), are produced by ozonolysis through the breaking
of a primary ozonide (POZ).

6. The ozonolysis reaction is highly exothermic. The
primary ozonide is formed with high internal energy.
Olzmann, M., Kraka, E., Cremer, D., Gutbrod, R. & Andersson, S. The Journal of Physical Chemistry A 101,
9421–9429 (1997).

7. CIs are formed with a broad energy distribution.
Olzmann, M., Kraka, E., Cremer, D., Gutbrod, R. & Andersson, S. The Journal of Physical Chemistry A 101,
9421–9429 (1997).
“hot” CI
“stabilized” CI

8. CIs with high internal energy (“hot” CIs), isomerize and
decompose rapidly, forming atmospherically relevant
products.
“vinoxy” radicalVinyl hydroperoxide (VHP)

9. CIs with low internal energy,
“stabilized” CIs (sCIs), can
competitively undergo unimolecular
dissociation and bimolecular reactions:
Vereecken, L., H. Harder, and A. Novelli. PCCP 16, no. 9 (2014).
 Recent developments in direct
measurement of sCIs produced from
CH2I2 photolysis (CH2I + O2) allowed
experimental measurement of rate
constants of CI reactions.
Welz, O. et al. Science 335, 204–207 (2012).

10. Measuring yields of sCIs
Scavenging
(e.g. w/ SO2)
Dimethyl dioxirane
SO3 + Acetone
H2SO4
y??
(1-y)??
R1R2CO + CI “hot” CI decomposition
isomerization
“stabilized” CI
collisional
stabilization/excitation
bimolecular
reactions
Alk + O3
(excess)
(∆O3)
(∆SO2) (∆H2SO4)or

11. Previous work on measuring sCI yields: Hatakeyama et al.
Hatakeyama, Shiro, Hiroshi Kobayashi, Zi Yu Lin, Hiroo Takagi, and
Hajime Akimoto. JPC 90, no. 17 (August 1986): 4131–35.
doi:10.1021/j100408a059.
Hatakeyama, Shiro, Hiroshi Kobayashi, and Hajime Akimoto. JPC
88, no. 20 (September 1984): 4736–39. doi:10.1021/j150664a058.
trans-2-butene
ethene
• High pressure to low pressure
• Measurement of ∆H2SO4

12. Previous work on measuring sCI yields: Drozd et al.
2,3-dimethyl-2-butene
• High pressure to low pressure
• Measurement of ∆HFA - ∆SOZ
Drozd, G. T., Kroll, J. & Donahue, N. M. JPCA 115,
161–166 (2011).
Hexafluoroacetone
Secondary ozonide

13. More recently: Hakala et al.
• High pressure to low pressure
• Measurement of ∆H2SO4
Hakala, J. P. & Donahue, N. M. JPCA 120, 2173–2178
(2016).

14. Experimental Setup
Ozonolysis of alkenes is done using a flow reactor:
Reaction products are measured using cavity ring-down
spectroscopy (CRDS).
Spectra of the main products is subtracted in order to look for CI
features.
Dye Laser PMT
To pump
Purge Purge
03
gen
FM
N2 inFM
SO2/HFA
in
FMTME
in
FM

15. CRDS:
Suitable for atmospheric measurements due to:
Long sample path (high sensitivity).
Real time measurements.
Portability (in situ measurements).

16.    
      )(
11
0


fNNN
L
dc
acacformformozoz 






)(f Contribution from
unknown products
Spectra analysis:
   
   






n
i
ii N
L
dc
L
dc

 0
11

17. Scavenging with SO2
Results
Scavenging
(e.g. w/ SO2)
Dimethyl dioxirane
SO3 + Acetone
H2SO4
y??
(1-y)??
R1R2CO + CI “hot” CI decomposition
isomerization
“stabilized” CI
collisional
stabilization/excitation
bimolecular
reactions
Alk + O3
(excess)
(∆O3)
(∆SO2)
Completely
consumed in
the reaction:
∆O3 = [O3]i

18.    
          

fNNNN
L
dc
acacSOSOformformozoz 





 22
0
11
SO2 + sCI  DMDO
SO2 + sCI  SO3 + Acetone
SO3 + H2O  H2SO4
∆SO2 can be measured directly in the reaction:
3 absorption features of SO2
between 320 – 325 nm

19. Determination of the yield of sCI by titration with SO2
𝑌𝑠𝐶𝐼 =
∆𝑆𝑂2
∆𝑂3

20. trans-2-butene ozonolysis
Hatakeyama, Shiro, Hiroshi Kobayashi, and Hajime Akimoto. The Journal of Physical Chemistry 88, no. 20 (September
1984): 4736–39. doi:10.1021/j150664a058.

21. 2,3-dimethyl-2-butene ozonolysis
Drozd, Greg T., Jesse Kroll, and Neil M. Donahue.The Journal of Physical Chemistry A 115, no. 2 (January 20, 2011): 161–66.
doi:10.1021/jp108773d.

22. Mechanistic implications
Copeland, Grant, Mariana V. Ghosh, Dudley E. Shallcross, Carl J. Percival, and John M. Dyke. Physical Chemistry Chemical
Physics 13, no. 39 (2011): 17461. doi:10.1039/c1cp21922g.

23. Mechanistic implications
C6H12 + O3  (CH3)2CO + y(P)[(CH3)2COO]* + [1-y(P)] (CH3)2COO
“hot” CI unimolecular decomposition and isomerization
“stabilized” CI bimolecular reactions

24. Summary
SO2 consumption measured by CRDS can be used to determine
yields of sCIs in ozonolysis reactions of alkenes.
Measurements of low pressure sCI yields were found for trans-2-
butene and 2,3-dimethyl-2-butene. The nascent yields of sCIs were
found by extrapolation to be 0 for trans-2-butene, and 0.15 for 2,3-
dimethyl-2-butene
Mechanism of secondary ozonolysis products needs to incorpórate
pressure-dependent sCI yield information.

25. Acknowledgements
Prof. Jingsong Zhang
Paul Jones
Mike Lucas
Ge Sun
Jian Chen
UCMEXUS Fellowship