Kinetic Study of the Gas-Phase Reactions of ... - ACS Publications

Article pubs.acs.org/JPCA

Kinetic Study of the Gas-Phase Reactions of Nitrate Radicals with Methoxyphenol Compounds: Experimental and Theoretical Approaches Amélie Lauraguais,†,‡ Atallah El Zein,†,‡ Cécile Coeur,*,†,‡ Emil Obeid,†,‡ Andy Cassez,†,‡ Marie-Thérèse Rayez,§,∥ and Jean-Claude Rayez§,∥ †

Université Lille Nord de France, 59658 Villeneuve d’Ascq Cedex, France Laboratoire de Physico-Chimie de l’Atmosphère, EA 4493, l’Université du Littoral Côte d’Opale, 62893 Wimereux, France § Université de Bordeaux, ISM, UMR 5255, F-33400 Talence, France ∥ CNRS, ISM, UMR 5255, F-33400 Talence, France ‡

S Supporting Information *

ABSTRACT: The gas-phase reactions of five methoxyphenols (three disubstituted and two trisubstituted) with nitrate radicals were studied in an 8000 L atmospheric simulation chamber at atmospheric pressure and 294 ± 2 K. The NO3 rate constants were investigated with the relative kinetic method using PTR−ToF−MS and GC-FID to measure the concentrations of the organic compounds. The rate constants (in units of cm3 molecule−1 s−1) determined were: 2-methoxyphenol (guaiacol; 2-MP), k(2‑MP) = (2.69 ± 0.57 × 10−11; 3-methoxyphenol (3-MP), k(3‑MP) = (1.15 ± 0.21) × 10−11; 4-methoxyphenol (4-MP), k(4‑MP) = (13.75 ± 7.97) × 10−11; 2-methoxy-4-methylphenol, k(2‑M‑4‑MeP) = (8.41 ± 5.58) × 10−11 and 2,6-dimethoxyphenol (syringol; 2,6-DMP), k(2,6‑DMP) = (15.84 ± 8.10) × 10−11. The NO3 rate constants of the studied methoxyphenols are compared with those of other substituted aromatics, and the differences in the reactivity are construed regarding the substituents (type, number and position) on the aromatic ring. This study was also supplemented by a theoretical approach of the methoxyphenol reactions with nitrate radicals. The upper limits of the NO3 overall rate constants calculated were in the same order of magnitude than those experimentally determined. Theoretical calculations of the minimum energies of the adducts formed from the reaction of NO3 radicals with the methoxyphenols were also performed using a DFT approach (M06-2X/6-31G(d,p)). The results indicate that the NO3 addition reactions on the aromatic ring of the methoxyphenols are exothermic, with energy values ranging between −13 and −21 kcal mol−1, depending on the environment of the carbon on which the oxygen atom of NO3 is attached. These energy values allowed identifying the most suitable carbon sites for the NO3 addition on the aromatic ring of the methoxyphenols: at the exception of the 3-MP, the NO3 ipso-addition to the hydroxyl group is one of the favored sites for all the studies compounds.

■

INTRODUCTION

methoxyphenols during the day is the reaction with hydroxyl radicals. Recent studies underlined the formation of secondary organic aerosols (SOA) from guaiacol and syringol with respect to their reaction with OH.8,10 In many environments, where aerosol concentrations were about 5 μg m−3, these reactions may have a relatively minor contribution to SOA production. In the nocturnal atmosphere, the nitrate radical is the dominant oxidant, and its reactivity with volatile organic compounds is similar to that of hydroxyl radical during daytime.13 Because of its fast diurnal photolysis, appreciable levels of NO3 can only accumulate at night, with concentration ranging from 5 × 107 to 1 × 1010 molecules cm−3.14,15

Methoxyphenols (MP) are emitted from biomass burning (including natural fires, human-initiated burning of vegetation, and residential wood combustion), they are produced from lignin pyrolysis. Guaiacol (2-methoxyphenol), syringol (2,6dimethoxyphenol), and their derivatives are the main representatives of this class of compounds.1−5 Methoxyphenols are semivolatile compounds with low molecular weight and they are present both in the gas- and particle- phases. The reactivity of the methoxyphenols with hydroxyl radicals and chlorine atoms has already been studied.6−10 Their atmospheric lifetimes with respect to their reaction toward OH and Cl are about 2 h (for [OH] = 1.6 × 106 molecules cm−3)11 and 20 h (for [Cl] = 5 × 104 atoms/cm3),12 respectively. So, even in the early hours of the morning in coastal urban areas where the chlorine atom concentrations are elevated, the main atmospheric degradation pathway of © XXXX American Chemical Society

Received: March 16, 2016 Revised: April 4, 2016

A

DOI: 10.1021/acs.jpca.6b02729 J. Phys. Chem. A XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry A However, some field campaigns16−18 showed that during the day, the NO3 concentrations were in range of 1.20 × 105 to 7.50 × 106 molecules cm−3 and these levels of NO3 may have non-negligible impacts on the atmospheric chemistry. It has been shown that 10 to 40% of DMS (dimethyl sulfide) can be oxidized by NO3 during daytime in marine area.16−18 In addition, models based on field measurements in US and Europe have suggested that the reaction of biogenic VOCs (monoterpenes and isoprene) with NO3 radicals could be important during the day within the forest canopy due to reduced light levels in this area.19,20 The reaction of NO3 radicals with aromatics is generally low; however it has been observed that the reaction of cresol isomers with nitrate radical can be a significant sink for these compounds during the night. Their recommended rate constants vary from 1.10 × 10−11 for m- and p-cresol to 1.40 × 10−11 cm3 molecule−1 s−1 for o-cresol.21 So, based on these literature data, one could expect that NO3 also plays a major role in the methoxyphenol degradation overnight. The objective of this study was to determine the rate constants of NO3 radicals with five methoxyphenols (three disubstituted and two trisubstituted): 2-methoxyphenol (guaiacol, 2-MP), 3-methoxyphenol (3-MP), 4-methoxyphenol (4MP), 2,6-dimethoxyphenol (syringol, 2,6-DMP) and 2methoxy-4-methylphenol (2-M-4-MeP). The reactivity of these oxygenated aromatics is then compared with that of other substituted aromatic compounds and construed regarding the substituents (type, number, and positions) on the aromatic ring. This study was also supplemented by a theoretical approach of the methoxyphenol reactions with nitrate radicals to calculate the upper limits of the NO3 overall rate constants. Calculations of the minimum energies of the adducts formed from the reaction of NO3 radicals with the methoxyphenols were also performed using a DFT approach (M06-2X/631G(d,p)) to identify the most suitable carbon sites for the NO3 addition on the aromatic ring. Finally the atmospheric implications of these reactions are discussed.

pentoxide crystals were collected in a second cold trap and were kept for several weeks at 188 K. The organic concentrations were analyzed every 10 s using a PTR−ToF−MS (proton transfer reaction−time of flight−mass spectrometer) instrument (PTR−ToF−MS 1000, Ionicon Analytik GmbH). They were measured by sampling (at 50 mL min−1) the chamber mixture into the PTR−ToF−MS drift tube through a heated peek inlet tube (333 K). The fragmentation of each compound was individually studied and were as follows: methoxyphenol isomers, m/z 125.1 (74%), 110.1 (24%), 93.1 (2%); 2-methoxy-4-methylphenol, m/z 139.2 (58%), 124.1 (27%), 107.1 (13%), 170.2 (2%); syringol, m/z 155.1 (64%), 140.1 (34%), 123.1 (2%); cresols, m/z 109.1 (87%), 94.1 (13%); catechol, m/z 111.1 (81%), 93.1 (19%); 3methylcatechol, m/z 125.1 (74%), 107.1 (26%); α-phellandrene, m/z 81 (76%), 137.2 (24%). To measure the reactant concentrations, the main fragment was solely monitored. Preliminary studies were also performed for each organic compound to verify that the oxidation products formed from their reaction with NO3 radicals do not overlap with the ions used to record the methoxyphenol and reference concentrations. For 2-MP, experiments were also done with a gas chromatograph equipped with a flame ionization detector (GC-FID PerkinElmer). The 2-MP and reference concentrations were regularly sampled before and during the experiments on stainless steel tubes filled with Tenax TA (60−80 mesh). The tubes were then thermally desorbed (Turbomatrix, PerkinElmer) and the organics separated onto a 30 m DB-5 capillary column held at 313 K during 5 min and then programmed to 523 at 5 K min−1. The initial mixing ratios of the different organic compounds used in this study were in the range (150−200) ppbV and (2− 3) ppm for the PTR−ToF−MS and GC-FID analysis, respectively. The compounds used in this study, their manufacturer, and stated purity were guaiacol (Alpha Aesar, 98%), 3-methoxyphenol (Alpha Aesar, 97%), 4-methoxyphenol (Alpha Aesar, 98%), 2-methoxy-4-methylphenol (Alfa Aesar, 98%), syringol (Acros, 99%), m-cresol (Merck, 99%), o-cresol (Merck, 99%), α-phellandrene (Acros, 99%), catechol (Merck, 99%), 3methylcatechol (Acros, 99%), dioxygene (Praxair, 99,5%), and nitrogen dioxide (Praxair, 99%). Theory: Computational Details. The geometries and energies of the methoxyphenols studied and the adducts formed from the NO3 radical addition on the aromatic ring were fully optimized using density functional theory (DFT) with the hybrid meta exchange−correlation functional M06-2X, coupled to the split valence basis set 6-31G(d,p). This functional, developed by Zhao and Truhlar,23 is well adapted for structures and energetics, specifically for the energy barrier determination. The unrestricted Hartree−Fock (UHF) formulation has been used as it is a convenient way to describe open-shell processes (due to NO3 radical). Its use is justified in our study since no significant spin contamination was found for all the stationary points explored. The optimization of each of these compounds is followed by a vibrational normal-mode analysis. All the calculations were carried out with the GAUSSIAN 09 package.24

■

METHODS Experimental Section. All the experiments were carried out in the dark, in a 8000 L Plexiglas indoor chamber at atmospheric pressure, (294 ± 2) K, and low relative humidity ( −CH3) toward the NO3 addition on the aromatic ring; the former donating electron density to the aromatic ring via mesomeric effect and the latter via inductive effect. The close

puzzling. Indeed, there is no evidence that the 4-MP is much more reactive toward NO3 radicals than the 2-MP and 3-MP since the dipole moment of 4-MP is a priori much smaller than those of 2-MP and 3-MP. Moreover, as all the MP systems studied, except 4-MP, have similar reduce masses and similar dipole moments, their overall long-range k(298) values are in the same order of magnitude. Only 4-MP has a long-range k(298) smaller than the other isomers which is in contradiction with the experiment. This result suggests that other parameters than the interaction potential of dipole−dipole type should be taken into account in the prevision of the rate constants of aromatic compounds with NO3 radicals. Comparison with Literature Data. To the best of our knowledge, this study represents the first determination of the rate constants for the reaction of the 3-MP and 4-MP with NO3; accordingly, no comparison with literature data is possible. However, the good accordance between the rate constants determined with different references suggests that the results are reliable and free of experimental artifacts. For 2-MP, 4-Me-2-MP, and 2,6-DMP, the NO3 rate constants measured in this study can be compared with those recently determined.30 In their article, Yang et al.30 reported the following values: k(2‑MP) = 3.2 × 10−12, k(4‑Me‑2MP) = 2.4 × 10−13 and k(2,6‑Me‑2MP) = 4.0 × 10−13 cm3 molecule−1, respectively, which are 1 to 2 orders of magnitude lower than the values determined in our work. Yang et al.30 observed that the 2-MP reactivity is about ten times higher than that of 4-Me-2-MP and 2,6-DMP and they mention that “2-MP exhibits an amazing reactivity with the NO3 radical and its rate constants is similar to that of phenol”. They suggest that the difference between the NO3 rate constants of the three MPs can be linked to the initial step of the reaction: for 2-MP and phenol, the NO3 reaction first proceeds via the NO3 addition to the C1 position adjacent to the hydroxyl group, whereas for 4-Me-2-MP and 2,6-DMP it occurs at a different C atom on the aromatic ring. They, however, do not propose any explanation to justify such different behaviors of the 3 MPs studied. In their work, Yang et al.30 used only one reference compound for the k(NO3) determination of each MP and a second one would have allowed to confirm the determined values. The disagreement between our values and those of Yang et al.30 is probably due to the high organic concentrations (about 53 ppm) used in the previous article. Yang et al.30 did not observe any wall losses for the MPs, which is rather surprising since these compounds are known to be very sticky and the concentrations used were quite high. This suggests that during the introduction step, the MPs adsorb on the chamber walls leading to an equilibrium with the gas-phase. Then, when the MPs react with the NO3 radicals, the equilibrium is modified and the walls release them in the gasphase, leading to an overestimation of their concentrations and an underestimation of the NO3 rate constants. Trends in Reactivity. In order to rationalize the experimental kNO3 values of the five methoxyphenols studied in this work, their reactivity were compared with that of other substituted aromatic compounds. Table 3 displays the measured rate constants for the reaction of NO3 with a range of methylated, methoxylated, and hydroxylated aromatics. The reaction of NO3 radicals with aromatic compounds may proceed either by addition of NO3 to the aromatic ring or by H atom abstraction from a substituent.19 Table 3 shows that the rate constants for the NO3 reactions with benzene (kbenzene < F

DOI: 10.1021/acs.jpca.6b02729 J. Phys. Chem. A XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry A reactivity of 3-MP and m-cresol is probably due to the meta position of the −CH3 and −OCH3 groups respectively in mcresol and 3-MP which do not activate the NO3 ipso-addition to the OH group site. Similarly, the methoxyphenols are more reactive than the xylene isomers (kxylenes = (2.32−4.53) × 10−16 cm3 molecule−1 s−1); the rate constants of xylenes being 6 orders of magnitude lower than those of methoxyphenols. Finally, the reactivity of catechol (1,2-dihydroxybenzene, k1,2‑DHB = 9.80 × 10−11 cm3 molecule−1 s−1) with NO3 radicals is about 6 times higher than that of 2-MP, suggesting that the effect of the hydroxyl group toward the NO3 addition is higher than that of the methoxy. As already observed, the highest rate constants for the reaction of methylated 1,2-dihydroxybenzene (k1,2‑DH‑3‑MB = 17.20 × 10−11 cm3 molecule−1 s−1; k1,2‑DH‑4‑MB = 14.70 × 10−11 cm3 molecule−1 s−1) compared to that of catechol is linked to the positive inductive effect of the −CH3 group.25 As indicated in Table 3, the reactivity of disubstituted aromatics with nitrate radicals depends on the nature and position of the substituents on the aromatic ring. It is wellknown that the −OCH3 group donates electron density to the aromatic ring via resonance effect and activates the NO3 addition to the ring in ortho and para positions (see Figure 2,

Figure 3. Geometry of the ipso-OH-4-MP-NO3 adduct calculated using the UM06-2X/6-31G(d,p) DFT method.

break more easily to form HNO3. This result comforts the mechanism of a NO3-radical ipso-addition to the substituent OH site followed by the hydrogen atom abstraction proposed by Atkinson29 for the reaction of phenols with NO3. The rate constant of 4-MP is however about 5 times higher than that of 2-MP, and regarding solely the substituents on the aromatic ring, this result was rather unexpected. So, as previously suggested, additional parameters have to be taken into account in the prevision of the rate constants for the reaction of the aromatics with NO3 radicals; the steric hindrance of the different sites for the NO3 addition should have also to be considered. In 4-MP, the hydroxylated carbon is less hindered than in 2-MP due to the presence of the methoxy group in para position to the hydroxyl, and the formation of the six-membered transition state after the NO3-radical ipsoaddition to the substituent OH site is thus favored compared to that for 2-MP where the methoxy group is in ortho-position to the hydroxyl substituent. The 2-M-4-MeP is also 3 times more reactive than the 2-MP due to the additional methyl group; the carbon bearing the − OH substituent is activated twice (once by the methoxy group in ortho and once by the methyl group in para; see Figure 2) for the ipso-addition of the nitrate radical. The same tendency is also observed for dimethylphenols which are 2−4 more reactive than methylphenols due to the presence of an extra methyl group. The theoretical calculations of the energy of the NO3methoxyphenol adducts (Table 2) show that the presence of the methyl group in para−OH position enhances the stability of the 2-M-4-MeP adducts by ∼2 kcal mol−1 with respect to that of the 2-MP. This value could explain the factor of 5 observed between the rate constants of the 2-M-4-MeP and the 2-MP. Similarly, the rate constant for the 2,6-DMP reaction with NO3 is higher than that of 2-MP; the presence of the second methoxy group raises the reactivity by a factor 8. In 2,6DMP, the two −OCH3 substituents are in ortho-position to the hydroxyl group, so the NO3-radical ipso-addition to the hydroxylated site is doubly activated (see Figure 2). This result is validated by the theory; the adduct formed from the NO3 ipso-addition to the hydroxyl group site of the 2,6-DMP is favored (Figure S9). Finally, the comparison of the reactivity of the five methoxyphenol isomers studied seems to confirm the hypothesis of Atkinson et al.;29 namely, the NO3-radical ipsoaddition to the substituent OH site and the formation a sixmembered transition state which can lead to the abstraction of the hydroxyl H to form HNO3 and methoxylated phenol. However, in order to definitively validate the mechanism involved in the reaction of methoxyphenols with NO3 radicals,

Figure 2. Methoxyphenols studied and the sites that are activated by the hydroxyl (●), methoxy (⬣) and methyl (⧫) groups toward electrophilic addition.

for the five methoxyphenols studied, the sites that are activated by the −OH, −OCH3, and −CH3 groups toward electrophilic addition). So, the highest reactivity of 2-MP and 4-MP compared to that of 3-MP could be attributed to the methoxy substituent which favors the NO3 ipso-addition to the carbon bearing the hydroxyl group and the formation of the sixmembered transition state described by Atkinson et al.29 The theoretical calculations of the minimum energies of the adducts formed from the reaction of NO3 radical with methoxyphenol isomers (Table 2 and Figures S5−S9) confirm that for 2-MP and 4-MP the NO3 ipso-addition to the hydroxyl group site is favored whereas for 3-MP, the NO3 addition on the aromatic ring is preferred in ortho-position to the OH. Figure 3 depicts the most stable ipso−OH-4-MP-NO 3 adduct with the occurrence of a hydrogen bond between one oxygen of the NO3 group and the hydrogen of the − OH substituent (dO‑‑‑H = 2.10 Å) leading to a six-membered H---ONOC1O which can evolve, through a cyclic transition state, to the formation of a methoxy-phenoxy radical and HNO3. This evolution is facilitated by a large C1---O(−NO2) distance of 1.53 Å (compared to the bond lengths of 1.34 and 1.38 Å for C− O(CH3) and C−(OH), respectively; see Figure 3) which can G

DOI: 10.1021/acs.jpca.6b02729 J. Phys. Chem. A XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry A

the Nord-Pas de Calais Regional Council, the French Ministry of Education and Research and European funds (FEDER). The CaPPA project (Chemical and Physical Properties of the Atmosphere) is funded by the French National Research Agency (ANR) through the PIA (Programme d’Investissement d’Avenir) under contract ANR-11-LABX-0005-01.

the characterization of the oxidation products formed in the gas-phase is required. Atmospheric Implications. The rate constants for the NO3-radical initiated oxidation of the 2-MP, 3-MP, 4-MP, 2-M4-MeP and 2,6-DMP allow us to determine their atmospheric lifetimes with respect to their reaction with NO3. Assuming typical nighttime concentrations of nitrate radicals of 5 × 108 molecules cm−3,31 the calculated lifetimes of the methoxyphenol isomers studied in this work are in the range from 13 to 174 s (see Table 4). The rate constants of methoxyphenols with

■

(1) Hays, M. D.; Geron, C. D.; Linna, K. J.; Smith, N. D.; Schauer, J. J. Speciation of Gas-Phase and Fine Particle Emissions from Burning of Foliar Fuels. Environ. Sci. Technol. 2002, 36, 2281−2295. (2) Mazzoleni, L. R.; Zielinska, B.; Moosmüller, H. Emissions of Levoglucosan, Methoxyphenols, and Organic Acids from Prescribed Burns, Laboratory Combustion of Wildland Fuels, and Residential Wood Combustion. Environ. Sci. Technol. 2007, 41, 2115−2122. (3) McDonald, J. D.; Zielinska, B.; Fujita, E. M.; Sagebiel, J. C.; Chow, J. C.; Watson, J. G. Fine Particle and Gaseous Emission Rates from Residential Wood Combustion. Environ. Sci. Technol. 2000, 34, 2080−2091. (4) Schauer, J. J.; Kleeman, M. J.; Cass, G. R.; Simoneit, B. R. T. Measurement of Emissions from Air Pollution Sources. 3. C1-C29 Organic Compounds from Fireplace Combustion of Wood. Environ. Sci. Technol. 2001, 35, 1716−1728. (5) Simpson, C. D.; Paulsen, M.; Dills, R. L.; Liu, L. J. S.; Kalman, D. A. Determination of Methoxyphenols in Ambient Atmospheric Particulate Matter: Tracers for Wood Combustion. Environ. Sci. Technol. 2005, 39, 631−637. (6) Coeur-Tourneur, C.; Cassez, A.; Wenger, J. C. Rate Constants for the Gas-Phase Reaction of Hydroxyl Radicals with 2-Methoxyphenol (Guaiacol) and Related Compounds. J. Phys. Chem. A 2010, 114, 11645−11650. (7) Lauraguais, A.; Coeur-Tourneur, C.; Cassez, A.; Seydi, A. Rate constant and secondary Organic Aerosol Yields for the Gas-Phase Reaction of Hydroxyl Radicals with Syringol (2,6-Dimethoxyphenol). Atmos. Environ. 2012, 55, 43−48. (8) Lauraguais, A.; Coeur-Tourneur, C.; Cassez, A.; Deboudt, K.; Fourmentin, M.; Choël, M. Atmospheric Reactivity of Hydroxyl Radicals with Guaiacol (2-methoxyphenol), a Biomass Burning Emitted Compound: Secondary Organic Aerosol Formation and Gas-Phase Oxidation Products. Atmos. Environ. 2014, 86, 155−163. (9) Lauraguais, A.; Bejan, I.; Barnes, I.; Wiesen, P.; Coeur-Tourneur, C.; Cassez, A. Rate Constant for the Gas-Phase Reaction of Chlorine Atoms with a Series of Methoxylated Aromatic Compounds. J. Phys. Chem. A 2014, 118, 1777−1784. (10) Lauraguais, A.; Bejan, I.; Barnes, I.; Wiesen, P.; Coeur, C. Rate Constants for the Gas-Phase Reaction of Hydroxyl Radicals with a Series of Methoxylated Aromatic Compounds. J. Phys. Chem. A 2015, 119, 6179−6187. (11) Prinn, R. G.; Weiss, R. F.; Miller, B. R.; Huang, F. N.; Alyea, J.; Cunnold, D. M.; Fraser, P. J.; Hartley, D. E.; Simmonds, P. J.Atmospheric Trends and Lifetime of CH3CCl3 and Global OH concentrations. Science 1995, 269, 187−192. (12) Spicer, C. W.; Chapman, E. G.; Finlayson-Pitts, B. J.; Plastridge, R. A.; Hubbe, J. M.; Fast, J. D.; Berkowitz, C. M. Unexpectedly High Concentrations of Molecular Chlorine in Coastral Air. Nature 1998, 394, 353−356. (13) Karagulian, F.; Rossi, M. J. The Heterogeneous Oxidation Kinetic of NO3 on Atmospheric Mineral Dust Surrogate. Phys. Chem. Chem. Phys. 2005, 7, 3150−3162. (14) Atkinson, R. Kinetics and Mechanisms of the Gas-Phase Reactions of the NO3 Radical with Organic Compounds. J. Phys. Chem. Ref. Data 1991, 20, 459−507. (15) Platt, U. F.; Winer, A. M.; Biermann, H. W.; Atkinson, R.; Pitts, J. N. Measurement of Nitrate Radical Concentrations in Continental Air. Environ. Sci. Technol. 1984, 18, 365−369. (16) Geyer, A.; Alicke, B.; Ackermann, R.; Martinez, M.; Harder, H.; Brune, W.; diCarlo, P.; Williams, E.; Jobson, T.; Hall, S.; Shetter, S.; Stutz, J. Direct Observation of Daytime NO3: Implications for Urban

Table 4. Atmospheric Lifetimes of Methoxyphenols with Respect to Their Reaction with Hydroxyl Radicals (OH), Chlorine Atoms (Cl) and Nitrate Radicals (NO3) compound

τOHa,b,c (h)

τCld,e (h)

τNO3f,g (s)

2-methoxyphenol 3-methoxyphenol 4-methoxyphenol 2-methoxy-4-methylphenol 2,6-dimethoxyphenol

2.3 1.8 1.8 1.8 1.8

19 19 19 17 21

74 174 15 23 13

a Coeur-Tourneur et al., 2010.6 bLauraguais et al., 2012.7 cτOH = 1/ kMP[OH], where [OH] = 1.6 × 106 molecules cm−3.11 dLauraguais et al., 2014.9 eτCl = 1/kMP[Cl], where [Cl] = 5 × 104 atoms/cm3.12 fThis work. gτNO3 = 1/kMP[NO3], where [NO3] = 5 × 108 molecules cm−3.31

hydroxyl radicals (OH)6,7,10 and chlorine atoms9 have also been previously determined and the corresponding estimated lifetimes are also reported in Table 4 for comparison. The reaction of methoxyphenols with OH radicals and Cl atoms leads to atmospheric lifetimes of about 2 h and 20 h, respectively. Consequently, the lifetime of methoxyphenols in the atmosphere is very short both during the day and the night and these reactions will therefore influence the formation of chemical oxidants on a local scale.

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpca.6b02729. Figures S1−S4, kinetic data plots for the reaction of 3MP, 4-MP, 2-M-4-MeP, and 2,6-DMP with nitrate radicals at (294 ± 3) K; Figures S5−S9, relative stability, ΔE0, of the adducts formed from the reaction of NO3 with 2-MP, 3-MP, 4-MP, 2-M-4-MeP, and 2,6-DMP; and section S10, theoretical NO3 rate constants calculated if NO3 is considered as a D3h symmetry system (PDF)

■

REFERENCES

AUTHOR INFORMATION

Corresponding Author

*Telephone: +33 321 99 64 05. Fax: +33 321 99 64 01. E-mail: [email protected] (C.C.). Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS We thank Pr. Bénédicte Picquet-Varrault (Laboratoire InterUniversitaire des Systèmes Atmosphériques, UMR CNRS 7583; Université Paris Est Créteil, FRANCE) for her help in the synthesis of the nitrogen pentoxide. The LPCA participate in the Research Institute of Industrial Environment (IRENI) which is financed by the Communauté Urbaine de Dunkerque, H

DOI: 10.1021/acs.jpca.6b02729 J. Phys. Chem. A XXXX, XXX, XXX−XXX

The Journal of Physical Chemistry A

■

Boundary Layer Chemistry. J. Geophys. Res. 2003, 108 (D12), 4368− 4378. (17) Brown, S. S.; Osthoff, H. D.; Stark, H.; Dube, W. P.; Ryerson, T. B.; Warneke, C.; de Gouw, J. A.; Wollny, A. G.; Parrish, D. D.; Fehsenfeld, F. C.; Ravishankara, A. R. Aircraft Observation of Daytime NO3 and N2O5 and their Implications for Tropospheric Chemistry. J. Photochem. Photobiol., A 2005, 176, 270−278. (18) Osthoff, D.; Sommariva, R.; Baynard, T.; Pettersson, A.; Williams, E. J.; Lerner, B. M.; Roberts, J. M.; Stark, H.; Goldan, P. D.; Kuster, W. C.; Bates, T. S.; Coffman, D.; Ravishankara, A. R.; Brown, S. S. Observation of Daytime N2O5 in the Marine Boundary Layer during New England Air Quality Study-Intercontinental Transport and Chemical Transformation 2004. J. Geophys. Res. 2006, 111 (D23), S14. (19) Forkel, R.; Klemm, O.; Graus, M.; Rappenglück, B.; Stockwell, W. R.; Grabmer, W.; Held, A.; Hansel, A.; Steinbrecher, R. Trace Gas Exchange and Gas Phase Chemistry in a Norway Spuce Forest: A Study with a Coupled 1-dimensional Canopy Atmospheric Chemistry Emission Model. Atmos. Environ. 2006, 40, 28−42. (20) Fuentes, J. D.; Wang, D.; Bowling, D. R.; Potosnak, M.; Monson, R. K.; Goliff, W. S.; Stockwell, W. R. Biogenic Hydrocarbon Chemistry within and Above a Mixed Deciduous Forest. J. Atmos. Chem. 2007, 56, 165−185. (21) Calvert, J. G.; Atkinson, R.; Becker, K. H.; Kamens, R. M.; Seinfeld, J. H.; Wallington, T. J.; Yarwood, G. The Mechanisms of Atmospheric Oxidation of Aromatic Hydrocarbons; Oxford University Press: New York, 2002. (22) Atkinson, R.; Carter, W. P. L.; Plum, C. N.; Winer, A. M.; Pitts, J. N. Kinetics of the Gas-Phase Reactions of NO3 Radicals with a Series of Aromatics at 296 ± 2 K. Int. J. Chem. Kinet. 1984, 16, 887−898. (23) Zhao, Y.; Truhlar, D. The M06 Suite of Density Functionals for main Group Thermochemistry, Thermochemical Kinetics, Noncovalent Interactions, Excited States, and Transition Elements: Two New Functionals and Systematic Testing of four M06-class functionals and 12 other functionals. Theor. Chem. Acc. 2008, 120, 215−241. (24) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A. et al.; Gaussian 09, Revision A.02, Gaussian, Inc.: Wallingford, CT, 2009. (25) Olariu, R. I.; Bejan, I.; Barnes, I.; Klotz, B.; Becker, K. H.; Wirtz, K. Rate Constants for the Gas-Phase Reaction of NO3 Radicals with Selected Dihydroxybenzenes. Int. J. Chem. Kinet. 2004, 36, 577−583. (26) Calvert, J. G.; Atkinson, R.; Kerr, J. A.; Madronich, S.; Moortgat, G. K.; Wallington, T. J.; Yarwood, G. The Mechanisms of Atmospheric Oxidation of the Alkenes; Oxford University Press: New York, 2000. (27) Hammond, G. S. A Correlation of Reaction Rates. J. Am. Chem. Soc. 1955, 77, 334−338. (28) Stoecklin, T.; Dateo, C. E.; Clary, D. C. Rate Constant Calculations on fast Diatom-Diatom Reactions. J. Chem. Soc., Faraday Trans. 1991, 87, 1667−1679. (29) Atkinson, R.; Aschmann, S. M.; Arey, J. Reactions of OH and NO3 Radicals with Phenol, Cresols, and 2-nitrophenol at 296 ± 2 K. Environ. Sci. Technol. 1992, 26, 1397−1403. (30) Yang, B.; Zhang, H.; Wang, Y.; Zhang, P.; Shu, J.; Sun, W.; Ma, P. Experimental and theoretical studies on gas-phase reactions of NO3 radicals with three methoxyphenols: Guaiacol, creosol, and syringol. Atmos. Environ. 2016, 125, 243−251. (31) Shu, Y.; Atkinson, R. Atmospheric Lifetimes and Fates of Series of Sesquiterpenes. J. Geophys. Res. 1995, 100, 7275−7281. (32) Kwok, E. S. C.; Atkinson, R.; Arey, J. Kinetics and Mechanisms of the Gas-Phase Reactions of the NO3 Radical with Aromatic Compounds. Int. J. Chem. Kinet. 1994, 26, 511−525. (33) Thüner, L. P.; Bardini, P.; Rea, G. J.; Wenger, J. C. Kinetics of the Gas-Phase Reactions of OH and NO 3 Radicals with Dimethylphenols. J. Phys. Chem. A 2004, 108, 11019−11025.

Article

NOTE ADDED AFTER ASAP PUBLICATION This article was published ASAP on April 25, 2016, without all of the corrections. The corrected article was published ASAP on April 26, 2016.

I

DOI: 10.1021/acs.jpca.6b02729 J. Phys. Chem. A XXXX, XXX, XXX−XXX