scholarly journals Technical note: Conversion of isoprene hydroxy hydroperoxides (ISOPOOHs) on metal environmental simulation chamber walls

2017 ◽  
Vol 17 (6) ◽  
pp. 4053-4062 ◽  
Author(s):  
Anne-Kathrin Bernhammer ◽  
Martin Breitenlechner ◽  
Frank N. Keutsch ◽  
Armin Hansel
Keyword(s):  
Gas Phase ◽  
Technical Note ◽  
Vinyl Ketone ◽  
Heterogeneous Reactions ◽  
Methyl Vinyl Ketone ◽  
Oxidation Products ◽  
Chemical Mechanism ◽  
Stainless Steel Surface ◽  
Methyl Vinyl

Abstract. Sources and sinks of isoprene oxidation products from low-NOx isoprene chemistry have been studied at the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber with a custom-built selective reagent ion time-of-flight mass spectrometer (SRI-ToF-MS), which allows quantitative measurement of isoprene hydroxy hydroperoxides (ISOPOOHs). The measured concentrations of the main oxidation products were compared to chemical box model simulations based on the Leeds Master Chemical Mechanism (MCM) v3.3. The modeled ISOPOOH concentrations are a factor of 20 higher than the observed concentrations, and methyl vinyl ketone (MVK) and methacrolein (MACR) concentrations are up to a factor of 2 lower compared to observations, despite the artifact-free detection method. Addition of catalytic conversion of 1,2-ISOPOOH and 4,3-ISOPOOH to methyl vinyl ketone (MVK) and methacrolein (MACR) on the stainless-steel surface of the chamber to the chemical mechanism resolves the discrepancy between model predictions and observation. This suggests that isoprene chemistry in a metal chamber under low-NOx conditions cannot be described by a pure gas phase model alone. Biases in the measurement of ISOPOOH, MVK, and MACR can be caused not only intra-instrumentally but also by the general experimental setup. The work described here extends the role of heterogeneous reactions affecting gas phase composition and properties from instrumental surfaces, described previously, to general experimental setups. The role of such conversion reactions on real environmental surfaces is yet to be explored.

scholarly journals Technical Note: Conversion of Isoprene Hydroxy Hydroperoxides (ISOPOOH) on Metal Environmental Simulation Chamber Walls

2016 ◽  
Author(s):  
Anne-Kathrin Bernhammer ◽  
Martin Breitenlechner ◽  
Frank N. Keutsch ◽  
Armin Hansel ◽  
Keyword(s):  
Gas Phase ◽  
Technical Note ◽  
Heterogeneous Reactions ◽  
Oxidation Products ◽  
Chemical Mechanism ◽  
Stainless Steel Surface ◽  
Sources And Sinks ◽  
Environmental Surfaces ◽  
Isoprene Oxidation

Abstract. Sources and sinks of isoprene oxidation products from low NOx isoprene chemistry have been studied at the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber with a custom-built selective reagent ion time of flight mass spectrometer (SRI-ToF-MS), which allows quantitative measurement of isoprene hydroxy hydroperoxides (ISOPOOH). The measured concentrations of the main oxidation products were compared to chemical box model simulations based on the Leeds Master Chemical Mechanism (MCM) v3.3. The modelled ISOPOOH concentrations are by a factor of 20 higher than the observed and methyl vinyl ketone (MVK) and methacrolein (MACR) concentrations are by a factor of up to 2 lower compared to observations, despite the artifact-free detection method. Addition of catalytic conversion of 1,2-ISOPOOH and 4,3-ISOPOOH to MVK and MACR on the stainless steel surface of the chamber to the chemical mechanism resolves the discrepancy between model predictions and observation. This suggests that isoprene chemistry in a metal chamber under low NOx conditions cannot be described by a pure gas phase model alone. Biases in the measurement of ISOPOOH, MVK and MACR can not only be caused intra-instrumentally but also by the general experimental setup. The work described here extends the role of heterogeneous reactions affection gas phase composition and properties from instrumental surfaces, described previously, to general experimental setups. The role of such conversion reactions on real environmental surfaces is yet to be explored.

scholarly journals Radical mechanisms of methyl vinyl ketone oligomerization through aqueous phase OH-oxidation: on the paradoxical role of dissolved molecular oxygen

2013 ◽  
Vol 13 (1) ◽  
pp. 2913-2954 ◽  
Author(s):  
P. Renard ◽  
F. Siekmann ◽  
A. Gandolfo ◽  
J. Socorro ◽  
G. Salque ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
High Resolution Mass Spectrometry ◽  
Organic Aerosol ◽  
Vinyl Ketone ◽  
Methyl Vinyl Ketone ◽  
Chemical Mechanism ◽  
Methyl Vinyl ◽  
Phase Chemistry ◽  
Dissolved O2

Abstract. It is now accepted that one of the important pathways of Secondary Organic Aerosol (SOA) formation occurs through aqueous phase chemistry in the atmosphere. However, the liquid phase chemical mechanisms leading to macromolecules are still not well understood. For α-dicarbonyl precursors, such as methylglyoxal and glyoxal, radical reactions through OH-oxidation produce oligomers, irreversibly and faster than accretion reactions. Methyl vinyl ketone (MVK) was chosen in the present study as it is an α, β-unsaturated carbonyl that can undergo such reaction pathways in the aqueous phase and forms even high molecular weight oligomers. We present here experiments on the aqueous phase OH-oxidation of MVK, performed under atmospheric relevant conditions. Using NMR and UV absorption spectroscopy, high and ultra-high resolution mass spectrometry, we show that the fast formation of oligomers up to 1800 Da is due to radical oligomerization of MVK, and 13 series of oligomers (out of a total of 26 series) are identified. The influence of atmospherically relevant parameters such as temperature, initial concentrations of MVK and dissolved oxygen are presented and discussed. In agreement with the experimental observations, we propose a chemical mechanism of OH-oxidation of MVK in the aqueous phase that proceeds via radical oligomerization of MVK on the olefin part of the molecule. This mechanism highlights the paradoxical role of dissolved O2: while it inhibits oligomerization reactions, it contributes to produce oligomerization initiator radicals, which rapidly consume O2, thus leading to the supremacy of oligomerization reactions after several minutes of reaction. These processes, together with the large ranges of initial concentrations investigated (60–656 μM of dissolved O2 and 0.2–20 mM of MVK) show the fundamental role that O2 likely plays in atmospheric organic aerosol.

scholarly journals Radical mechanisms of methyl vinyl ketone oligomerization through aqueous phase OH-oxidation: on the paradoxical role of dissolved molecular oxygen

2013 ◽  
Vol 13 (13) ◽  
pp. 6473-6491 ◽  
Author(s):  
P. Renard ◽  
F. Siekmann ◽  
A. Gandolfo ◽  
J. Socorro ◽  
G. Salque ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
High Resolution Mass Spectrometry ◽  
Vinyl Ketone ◽  
Methyl Vinyl Ketone ◽  
Chemical Mechanism ◽  
Radical Oxidation ◽  
Methyl Vinyl ◽  
Chemical Mechanisms ◽  
Phase Chemistry

Abstract. It is now accepted that one of the important pathways of secondary organic aerosol (SOA) formation occurs through aqueous phase chemistry in the atmosphere. However, the chemical mechanisms leading to macromolecules are still not well understood. It was recently shown that oligomer production by OH radical oxidation in the aerosol aqueous phase from α-dicarbonyl precursors, such as methylglyoxal and glyoxal, is irreversible and fast. Methyl vinyl ketone (MVK) was chosen in the present study as it is an α,β-unsaturated carbonyl that can undergo radical oligomerization in the aerosol aqueous phase. We present here experiments on the aqueous phase OH-oxidation of MVK, performed under various conditions. Using NMR and UV absorption spectroscopy, high and ultra-high resolution mass spectrometry, we show that the fast formation of oligomers up to 1800 Da is due to radical oligomerization of MVK, and 13 series of oligomers (out of a total of 26 series) are identified. The influence of atmospherically relevant parameters such as temperature, initial concentrations of MVK and dissolved oxygen are presented and discussed. In agreement with the experimental observations, we propose a chemical mechanism of OH-oxidation of MVK in the aqueous phase that proceeds via radical oligomerization of MVK on the olefin part of the molecule. This mechanism highlights in our experiments the paradoxical role of dissolved O2: while it inhibits oligomerization reactions, it contributes to produce oligomerization initiator radicals, which rapidly consume O2, thus leading to the dominance of oligomerization reactions after several minutes of reaction. These processes, together with the large range of initial concentrations investigated show the fundamental role that radical oligomerization processes likely play in polluted fogs and atmospheric aerosol.

scholarly journals Aqueous phase oligomerization of methyl vinyl ketone through photooxidation – Part 2: Development of the chemical mechanism and atmospheric implications

2014 ◽  
Vol 14 (15) ◽  
pp. 21565-21609 ◽  
Author(s):  
B. Ervens ◽  
P. Renard ◽  
S. Ravier ◽  
J.-L. Clément ◽  
A. Monod
Keyword(s):  
Gas Phase ◽  
Aqueous Phase ◽  
Formation Rate ◽  
Liquid Water Content ◽  
Vinyl Ketone ◽  
Methyl Vinyl Ketone ◽  
Chemical Mechanism ◽  
Atmospheric Conditions ◽  
Methyl Vinyl ◽  
Oligomer Formation

Abstract. We developed a chemical mechanism based on laboratory experiments that have shown efficient oligomerization from methyl vinyl ketone (MVK) in the bulk aqueous phase. Kinetic data are applied (if known) or fitted to the observed MVK decay and oligomer mass increase. The mechanism is then implemented into a multiphase box model that simulates (i) oligomer formation upon uptake of MVK from the gas phase, and (ii) SOA formation from isoprene, as a precursor of MVK and methacrolein (MACR) in the aqueous and gas phases. Model results show that under atmospheric conditions, the oligomer formation rate strongly depends on the availability of dissolved oxygen. If oxygen is consumed too quickly or its solubility is kinetically or thermodynamically limited, oligomerization is accelerated, in agreement with the laboratory studies. The comparison of predicted oligomer formation shows that for most model assumptions (e.g. depending on the assumed partitioning of MVK and MACR), SOA formation from isoprene in the gas phase exceeds aqueous SOA formation by a factor 3–4. However, at high aerosol liquid water content and potentially high partitioning of oligomer precursors into the aqueous phase, SOA formation in both phases might be equally efficient.

scholarly journals Knockout of Arabidopsis thaliana VEP1, Encoding a PRISE (Progesterone 5β-Reductase/Iridoid Synthase-Like Enzyme), Leads to Metabolic Changes in Response to Exogenous Methyl Vinyl Ketone (MVK)

Metabolites ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 11
Author(s):  
Jan Klein ◽  
Mona Ernst ◽  
Alexander Christmann ◽  
Marina Tropper ◽  
Tim Leykauf ◽  
...  
Keyword(s):  
Metabolic Networks ◽  
Vinyl Ketone ◽  
Methyl Vinyl Ketone ◽  
General Role ◽  
Methyl Vinyl ◽  
Knockout Mutants ◽  
Number Of Genes ◽  
Vein Patterning ◽  
And Function

Small or specialized natural products (SNAPs) produced by plants vary greatly in structure and function, leading to selective advantages during evolution. With a limited number of genes available, a high promiscuity of the enzymes involved allows the generation of a broad range of SNAPs in complex metabolic networks. Comparative metabolic studies may help to understand why—or why not—certain SNAPs are produced in plants. Here, we used the wound-induced, vein patterning regulating VEP1 (AtStR1, At4g24220) and its paralogue gene on locus At5g58750 (AtStR2) from Arabidopsis to study this issue. The enzymes encoded by VEP1-like genes were clustered under the term PRISEs (progesterone 5β-reductase/iridoid synthase-like enzymes) as it was previously demonstrated that they are involved in cardenolide and/or iridoid biosynthesis in other plants. In order to further understand the general role of PRISEs and to detect additional more “accidental” roles we herein characterized A. thaliana steroid reductase 1 (AtStR1) and compared it to A. thaliana steroid reductase 2 (AtStR2). We used A. thaliana Col-0 wildtype plants as well as VEP1 knockout mutants and VEP1 knockout mutants overexpressing either AtStR1 or AtStR2 to investigate the effects on vein patterning and on the stress response after treatment with methyl vinyl ketone (MVK). Our results added evidence to the assumption that AtStR1 and AtStR2, as well as PRISEs in general, play specific roles in stress and defense situations and may be responsible for sudden metabolic shifts.

scholarly journals Yields of oxidized volatile organic compounds during the OH radical initiated oxidation of isoprene, methyl vinyl ketone, and methacrolein under high-NO<sub>x</sub> conditions

2011 ◽  
Vol 11 (21) ◽  
pp. 10779-10790 ◽  
Author(s):  
M. M. Galloway ◽  
A. J. Huisman ◽  
L. D. Yee ◽  
A. W. H. Chan ◽  
C. L. Loza ◽  
...  
Keyword(s):  
Secondary Production ◽  
First Generation ◽  
Vinyl Ketone ◽  
Methyl Vinyl Ketone ◽  
Chemical Mechanism ◽  
Total Production ◽  
Production Term ◽  
Methyl Vinyl ◽  
Chemical Mechanisms ◽  
Master Chemical Mechanism

Abstract. We present first-generation and total production yields of glyoxal, methylglyoxal, glycolaldehyde, and hydroxyacetone from the oxidation of isoprene, methyl vinyl ketone (MVK), and methacrolein (MACR) with OH under high NOx conditions. Several of these first-generation yields are not included in commonly used chemical mechanisms, such as the Leeds Master Chemical Mechanism (MCM) v. 3.2. The first-generation yield of glyoxal from isoprene was determined to be 2.1 (±0.6)%. Inclusion of first-generation production of glyoxal, glycolaldehyde and hydroxyacetone from isoprene greatly improves performance of an MCM based model during the initial part of the experiments. In order to further improve performance of the MCM based model, higher generation glyoxal production was reduced by lowering the first-generation yield of glyoxal from C5 hydroxycarbonyls. The results suggest that glyoxal production from reaction of OH with isoprene under high NOx conditions can be approximated by inclusion of a first-generation production term together with secondary production only via glycolaldehyde. Analogously, methylglyoxal production can be approximated by a first-generation production term from isoprene, and secondary production via MVK, MACR and hydroxyacetone. The first-generation yields reported here correspond to less than 5% of the total oxidized yield from isoprene and thus only have a small effect on the fate of isoprene. However, due to the abundance of isoprene, the combination of first-generation yields and reduced higher generation production of glyoxal from C5 hydroxycarbonyls is important for models that include the production of the small organic molecules from isoprene.

scholarly journals Production of methyl vinyl ketone and methacrolein via the hydroperoxyl pathway of isoprene oxidation

2013 ◽  
Vol 13 (11) ◽  
pp. 5715-5730 ◽  
Author(s):  
Y. J. Liu ◽  
I. Herdlinger-Blatt ◽  
K. A. McKinney ◽  
S. T. Martin
Keyword(s):  
Reaction Pathway ◽  
Vinyl Ketone ◽  
Methyl Vinyl Ketone ◽  
Oxidation Products ◽  
Peroxyl Radicals ◽  
Cold Trap ◽  
Product Analysis ◽  
Methyl Vinyl ◽  
Isoprene Oxidation ◽  
Tof Ms

Abstract. The photo-oxidation chemistry of isoprene (ISOP; C5H8) was studied in a continuous-flow chamber under conditions such that the reactions of the isoprene-derived peroxyl radicals (RO2) were dominated by the hydroperoxyl (HO2) pathway. A proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) with switchable H3O+ and NO+ reagent ions was used for product analysis. The products methyl vinyl ketone (MVK; C4H6O) and methacrolein (MACR; C4H6O) were differentiated using NO+ reagent ions. The MVK and MACR yields via the HO2 pathway were (3.8 ± 1.3)% and (2.5 ± 0.9)%, respectively, at +25 °C and < 2% relative humidity. The respective yields were (41.4 ± 5.5)% and (29.6 ± 4.2)% via the NO pathway. Production of MVK and MACR via the HO2 pathway implies concomitant production of hydroxyl ((6.3 ± 2.1)%) and hydroperoxyl ((6.3 ± 2.1)%) radicals, meaning a HOx recycling of (12.6 ± 4.2)% given that HO2 was both a reactant and product. Other isoprene oxidation products, believed to be mostly organic hydroperoxides, also contributed to the ion intensity at the same mass-to-charge (m/z) ratios as the MVK and MACR product ions for HO2-dominant conditions. These products were selectively removed from the gas phase by placement of a cold trap (−40 °C) inline prior to the PTR-TOF-MS. When incorporated into regional and global chemical transport models, the yields of MVK and MACR and the concomitant HOx recycling reported in this study can improve the accuracy of the simulation of the HO2 reaction pathway of isoprene, which is believed to be the fate of approximately half of atmospherically produced isoprene-derived peroxy radicals on a global scale.

Sign in / Sign up

Export Citation Format

Share Document