دانلود رایگان مقاله لاتین تغییر هیدروژن در رادیکال پراکسی از سایت الزویر
عنوان فارسی مقاله:
واکنش تغییر هیدروژن در رادیکال های پراکسی چهار متیل بوتانول (MBO) و تاثیر آنها بر جو
عنوان انگلیسی مقاله:
Hydrogen shift reactions in four methyl-buten-ol (MBO) peroxy radicals and their impact on the atmosphere
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Methyl-buten-ol (MBO) molecules are emitted from many different natural sources (Baker et al., 1999; Goldan et al., 1993; Harley et al., 1998; Koenig et al., 1995). The most important biogenic emitted MBO is the 2-methyl-3-buten-2-ol (MBO232) with an estimated global emission around 1.6e2.2 Tg yr1 (Guenther et al., 2012; Sindelarova et al., 2014). Although the global emission of MBO232 is 200e400 times lower than the emission of isoprene (500e600 Tg yr1 ) (Guenther et al., 2012; Sindelarova et al., 2014), the local concentration of MBO232 can exceed the concentration of isoprene in some regions. In the Colorado Mountains the daytime mixing ratio of MBO232 is measured to be 2e3 ppb, which is about 4e7 times greater than the concentration * Corresponding author. of isoprene (0.4e0.6 ppb) (Goldan et al., 1993).The oxidation of MBO232 in the atmosphere is initiated by the reaction with the hydroxyl (OH) radical. This reaction has been investigated both experimentally and theoretically (Alvarado et al., 1999; Baasandorj and Stevens, 2007; Carrasco et al., 2007; Chan et al., 2009; Fantechi et al., 1998; Ferronato et al., 1998; Reisen et al., 2003). The rate constant for MBO232 þ OH is measured to 6.3 1011cm3 molecules-1 s 1 (Baasandorj and Stevens, 2007). Here the OH radical adds to the double bond in MBO232, where the addition occurs at the terminal carbon atom with a probability of 0.7 (Alvarado et al., 1999; Baasandorj and Stevens, 2007). The subsequent addition of molecular oxygen produces a peroxy radical (MBO232-RO2). The oxidation of MBO232 produces secondary organic aerosols (SOA), when the NO concentration is low (Chan et al., 2009; Jaoui et al., 2012; Zhang et al., 2012). It is proposed, that the possible formation of the SOA is due to the production of C5-triols, by a self-reaction between two MBO232-RO2 radicals (Chan et al., 2009). Recently, it is suggested, that an internal hydrogen transfer reaction (H-shift) from an alcohol group could lead to the formation of epoxides (Zhang et al., 2014). Current results suggest that epoxides might be an important SOA precursor, which could contribute to SOA production in forest regions (Paulot et al., 2009; St. Clair et al., 2016; Zhang et al., 2012, 2014). In general, peroxy radicals (RO2) can self-react (RO2 þ RO2), react with NO/HO2, or undergo an internal transfer of a hydrogen atom (H-shift reaction). If the H-shift reaction is fast and/or if the concentration of NO/HO2 is low, like in remote forest regions, the Hshift reactions become important for RO2. The rate constants of the pseudo-first order reaction between RO2 and NO/HO2 are estimated to be around 102 s 1 in remote forest regions with ambient temperature and pressure (Orlando and Tyndall, 2012). In H-shift reactions, RO2 transfers a hydrogen atom internally and produces a QOOH radical. The QOOH radical can hereafter decompose into smaller molecules, or react with O2 and produce a new peroxy (OOQOOH) radical. The OOQOOH radicals can then again undergo a H-shift reactions or reacts with NO or HO2. This process is known as autoxidation (Crounse et al., 2013). RO2 can undergo a number of unimolecular decomposition reactions (predominantly, internal transfer of a hydrogen atom). The H-shift reaction of an aldehydic hydrogen atom has been shown to be important in the atmosphere with a rate constant of around 0.5 s 1 (Crounse et al., 2012). Very recently, the H-shift reaction from a hydroperoxy group and an enol have been estimated to be very fast with rate constants of about 103 s 1 and 106 s 1 , respectively (Jørgensen et al., 2016; Peeters and Nguyen, 2012). The H-shift autoxidation mechanism has been shown to produce extremely low-volatility organic compounds (ELVOCs) by introducing a large amount of hydroperoxy groups into the VOCs (Rissanen et al., 2014). In the oxidation of isoprene, H-shift reactions will compete with the bimolecular reaction of RO2 with NO/HO2 (Crounse et al., 2011; Peeters et al., 2009). There are six different isoprene derived peroxy radicals. Two of the isoprene derived peroxy radicals, HOCH2CHC(CH3)CH2(OO) and HOCH2C(CH3)CHCH2(OO), can undergo a 1,6-CH H-shift reaction leading to the production of C5- hydroperoxyaldehydes (HPALDs) (Peeters et al., 2009), whereas the four other isoprene derived peroxy radicals, (HOCH2C(CH3)(OO) CHCH2, (OO)CH2C(CH3)(OH)CHCH2, HOCH2CH(OO)C(CH3) CH2 and (OO)CH2CH(OH)C(CH3)CH2), can undergo a 1,5-OH H-shift reaction. The rate constants of the 1,5-OH H-shift reactions are estimated to be in the range 104 -102 s 1 at 300 K (Da Silva et al., 2010; Peeters et al., 2009, 2014). Here, we will investigate the possible H-shift reactions in peroxy radicals derived from the OH radical oxidation of four different MBOs (2-methyl-3-buten-2-ol (MBO232), 2-methyl-3-buten-1-ol (MBO231), 3-methyl-3-buten-2-ol (MBO332) and 3-methyl-3- buten-1-ol (MBO331)). The position of the methyl group, carboncarbon double bond and alcohol group are the first, second and third number, respectively. The molecular structures are shown in Fig. 1. We will also investigate a possible reaction mechanism for the formation of epoxides from the peroxy radicals derived from MBO232. Furthermore, we will simulate the atmospheric impact of the OH radical oxidation of MBO232, using the GEOS-Chem chemical transport model (Bey et al., 2001) and employing the MEGAN 2.1 emission inventory (Guenther et al., 2012). 2. Compu
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کلمات کلیدی:
Rapid Hydrogen Shift Scrambling in Hydroperoxy ... - ACS Publications pubs.acs.org/doi/abs/10.1021/acs.jpca.5b06768 by S Jørgensen - 2016 - Cited by 12 - Related articles Dec 15, 2015 - For peroxy radicals with an OOH substituent, the H-shift reaction from the .... Hydrogen shift reactions in four methyl-buten-ol (MBO) peroxy ... Rapid Hydrogen Shift Scrambling in Hydroperoxy ... - ACS Publications pubs.acs.org/doi/full/10.1021/acs.jpca.5b06768 by S Jørgensen - 2016 - Cited by 12 - Related articles Dec 15, 2015 - For peroxy radicals with an OOH substituent, the H-shift reaction from the ...... Hydrogen shift reactions in four methyl-buten-ol (MBO) peroxy ... Rapid Hydrogen Shift Scrambling in Hydroperoxy ... - ACS Publications pubs.acs.org/doi/abs/10.1021/acs.jpca.5b06768?src=recsys Dec 15, 2015 - For peroxy radicals with an OOH substituent, the H-shift reaction from the ... Hydrogen shift reactions in four methyl-buten-ol (MBO) peroxy ... Experimental and Theoretical Studies of the Kinetics of the Reactions ... pubs.acs.org/doi/abs/10.1021/jp066286x by M Baasandorj - 2007 - Cited by 16 - Related articles Jan 5, 2007 - Hydrogen shift reactions in four methyl-buten-ol (MBO) peroxy radicals and their impact on the atmosphere. Hasse C. Knap , Johan A. Schmidt ... Hydroxyaldehyde Products from Hydroxyl Radical Reactions of Z-3 ... pubs.acs.org/doi/abs/10.1021/es034142f by F Reisen - 2003 - Cited by 69 - Related articles Sep 10, 2003 - Hydroxyaldehyde products of the OH radical-initiated reactions (in the presence of ... Kinetics and Products of the Reactions of OH Radicals with 4,4-Dimethyl-1-pentene and 3 ... Photooxidation of 2-Methyl-3-Buten-2-ol (MBO) as a Potential ... Paul O. Wennberg , Richard C. Flagan and John H. Seinfeld. Rate and mechanism of the reactions of OH and Cl with 2-methyl-3 ... onlinelibrary.wiley.com/doi/10.1029/98JD00528/abstract by C Ferronato - 1998 - Cited by 83 - Related articles Oct 1, 1998 - ... k1 for the gas-phase reaction of OH with 2-methyl-3-buten-2-ol (MBO, ... acetone, (50±5)% glycolaldehyde, and (35±4)% formaldehyde.
