- Nitrate ion photochemistry at interfaces: A new mechanism for oxidation of α-pinene
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The photooxidation of 0.6-0.9 ppm α-pinene in the presence of a deliquesced thin film of NaNO3, and for comparison increasing concentrations of NO2, was studied in a 100 L Teflon chamber at relative humidities from 72-88% and temperatures from 296-304 K. The loss of α-pinene and the formation of gaseous products were followed with time using proton transfer mass spectrometry. The yields of gas phase products were smaller in the NaNO3 experiments than in NO2 experiments. In addition, pinonic acid, pinic acid, trans-sobrerol and other unidentified products were detected in the extracts of the wall washings only for the NaNO3 photolysis. These data indicate enhanced loss of α-pinene at the NaNO3 thin film during photolysis. Supporting the experimental results are molecular dynamics simulations which predict that α-pinene has an affinity for the surface of the deliquesced nitrate thin film, enhancing the opportunity for oxidation of the impinging organic gas during the nitrate photolysis. This new mechanism of oxidation of organics may be partially responsible for the correlation between nitrate and the organic component of particles observed in many field studies, and may also contribute to the missing source of SOA needed to reconcile model predictions and field measurements. In addition, photolysis of nitrate on surfaces in the boundary layer may lead to oxidation of co-adsorbed organics. the Owner Societies.
- Yu, Yong,Ezell, Michael J.,Zelenyuk, Alla,Imre, Dan,Alexander, Liz,Ortega, John,Thomas, Jennie L.,Gogna, Karun,Tobias, Douglas J.,D'Anna, Barbara,Harmon, Chris W.,Johnson, Stanley N.,Finlayson-Pitts, Barbara J.
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- Surfactant-Assisted Ozonolysis of Alkenes in Water: Mitigation of Frothing Using Coolade as a Low-Foaming Surfactant
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Aqueous-phase ozonolysis in the atmosphere is an important process during cloud and fog formation. Water in the atmosphere acts as both a reaction medium and a reductant during the ozonolysis. Inspired by the atmospheric aqueous-phase ozonolysis, we herein report the ozonolysis of alkenes in water assisted by surfactants. Several types of surfactants, including anionic, cationic, and nonionic surfactants, were investigated. Although most surfactants enhanced the solubility of alkenes in water, they also generated excessive foaming during the ozone bubbling, which led to the loss of products. Mitigation of the frothing was accomplished by using Coolade as a nonionic and low-foaming surfactant. Coolade-assisted ozonolysis of alkenes in water provided the desired carbonyl products in good yields and comparable to those achieved in organic solvents. During the ozonolysis reaction, water molecules trapped within the polyethylene glycol region of Coolade were proposed to intercept the Criegee intermediate to provide a hydroxy hydroperoxide intermediate. Decomposition of the hydroxy hydroperoxide led to formation of the carbonyl product without the need for a reductant typically required for the conventional ozonolysis using organic solvents. This study presents Coolade as an effective surfactant to improve the solubility of alkenes while mitigating frothing during the ozonolysis in water.
- Buntasana, Supanat,Hayashi, Jun,Klumphu, Piyatida,Padungros, Panuwat,Saetung, Prakorn,Vilaivan, Tirayut
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supporting information
(2022/02/23)
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- Nickel-Catalyzed Selective Reduction of Carboxylic Acids to Aldehydes
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The direct reduction of carboxylic acids to aldehydes is a fundamental transformation in organic synthesis. The combination of an air-stable Ni precatalyst, dimethyl dicarbonate as an activator, and silane reductant effects this reduction for a wide variety of substrates, including pharmaceutically relevant structures, in good yields and with no overreduction to alcohols. Moreover, this methodology is scalable, allows access to deuterated aldehydes, and is also compatible with one-pot utilization of the aldehyde products.
- Iosub, Andrei V.,Morav?ík, ?tefan,Wallentin, Carl-Johan,Bergman, Joakim
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supporting information
p. 7804 - 7808
(2019/10/14)
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- Chemical characterization of α-pinene secondary organic aerosol constituents using gas chromatography, liquid chromatography, and paper spray-based mass spectrometry techniques
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Rationale: Despite ample research into the atmospheric oxidation of α-pinene, an important precursor to biogenic secondary organic aerosol formation, the identification of its reaction products, specifically organic nitrates, which impact atmospheric NOx concentrations, is still incomplete. This negatively impacts our understanding of α-pinene oxidation chemistry and its relation to air quality. Methods: Photochemical chamber experiments were conducted in conjunction with mass spectrometric techniques, including gas chromatography/mass spectrometry (GC/MS), high-performance liquid chromatography/time-of-flight (HPLC/TOF), and paper spray ionization MS, to investigate products from the OH radical initiated oxidation of α-pinene under high NOx conditions. Results: Over 30 compounds were tentatively identified, including those newly detected from photochemical chamber studies of α-pinene oxidation, pinocamphenol, fencholenic aldehyde, and α-pinene-derived nitrate isomers. α-Pinene-derived hydroxynitrate isomers were successfully detected using chromatographic methods, demonstrating, for the first time, the identification of individual first-generation organic nitrate products derived from α-pinene. The application of paper spray ionization to particle-phase compounds collected on filters represents a novel method for the direct analysis of filter samples at ambient pressure and temperature. Conclusions: The use of HPLC/TOF and paper spray ionization methods to identify previously unobserved α-pinene-derived products helps lower the uncertainty in α-pinene oxidation chemistry and provides new platforms that can be used to identify and quantify important atmospheric compounds that relate to air quality in a complex sample matrix, such as ambient aerosol particles. Additionally, the use of paper spray ionization for direct filter analysis is a fast, relatively inexpensive sample preparation technique that can be used to reduce sample manipulation from solvent-induced reactions. Copyright
- Rindelaub, Joel D.,Shepson, Paul B.,Wiley, Joshua S.,Cooper, Bruce R.
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p. 1627 - 1638
(2016/09/08)
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- A selective, efficient and environmentally friendly method for the oxidative cleavage of glycols
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A catalytic methodology for the oxidative cleavage of vicinal diols is described as an advantageous alternative in terms of the environmental impact on classical methods involving toxic oxidants. The novel strategy is based on the use of dioxomolybdenum(vi) complexes as catalysts and dimethyl sulfoxide (DMSO) as an oxidant and displays high selectivity and a broad scope for glycol cleavage. In addition, the developed system is also useful for the oxidation of acyloins to diketones.
- García, Nuria,Rubio-Presa, Rubén,García-García, Patricia,Fernández-Rodríguez, Manuel A.,Pedrosa, María R.,Arnáiz, Francisco J.,Sanz, Roberto
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p. 2335 - 2340
(2016/05/19)
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- Fe-catalyzed one-pot oxidative cleavage of unsaturated fatty acids into aldehydes with hydrogen peroxide and sodium periodate
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A one-pot method has been developed for the oxidative cleavage of internal alkenes into aldehydes by using 0.5mol % of the nonheme iron complex [Fe(OTf)2(mix-bpbp)] (bpbp=N,N'-bis(2-picolyl)-2,2'-bipyrrolidine) as catalyst and 1.5equivalents of hydrogen peroxide and 1equivalent of sodium periodate as oxidants. A mixture of diastereomers of the chiral bpbp ligand can be used, thereby omitting the need for resolution of its optically active components. The cleavage reaction can be performed in one pot within 20h and under ambient conditions. Addition of water after the epoxidation, acidification and subsequent pH neutralization are crucial to perform the epoxidation, hydrolysis, and subsequent diol cleavage in one pot. High aldehyde yields can be obtained for the cleavage of internal aliphatic double bonds with cis and trans configuration (86-98 %) and unsaturated fatty acids and esters (69-96 %). Good aldehyde yields are obtained in reactions of trisubstituted and terminal alkenes (62-63 %). The products can be easily isolated by a simple extraction step with an organic solvent. The presented protocol involves a lower catalyst loading than conventional methods based on Ru or Os. Also, hydrogen peroxide can be used as the oxidant in this case, which is often disproportionated by second- and third-row metals. By using only mild oxidants, overoxidation of the aldehyde to the carboxylic acid is prevented. Copyright
- Spannring, Peter,Yazerski, Vital,Bruijnincx, Pieter C. A.,Weckhuysen, Bert M.,Klein Gebbink, Robertus J. M.
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p. 15012 - 15018
(2013/11/06)
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- Mechanisms for the formation of secondary organic aerosol components from the gas-phase ozonolysis of α-pinene
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Gas-phase ozonolysis of α-pinene was studied in static chamber experiments under 'OH-free' conditions. A range of multifunctional products-in particular low-volatility carboxylic acids-were identified in the condensed phase using gas chromatography coupled to mass spectrometry after derivatisation. The dependence of product yields on reaction conditions (humidity, choice of OH radical scavengers, added Criegee intermediate scavengers, NO2etc.) was investigated to probe the mechanisms of formation of these products; additional information was obtained by studying the ozonolysis of an enal and an enone derived from α-pinene. On the basis of experimental findings, previously suggested mechanisms were evaluated and detailed gas-phase mechanisms were developed to explain the observed product formation. Atmospheric implications of this work are discussed. the Owner Societies.
- Ma, Yan,Russell, Andrew T.,Marston, George
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p. 4294 - 4312
(2008/12/22)
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- Oxidative cleavage of vicinal diols: IBX can do what Dess-Martin periodinane (DMP) can
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A study was conducted to demonstrate the similarity of reactivity between o-iodoxybenzoic acid (IBX), an oxidative agent of vicinal diols and Des-Martin periodinane (DMP). The study examined IBX-mediated oxidative cleavage of tert,tert-1,2-diols and discovered pathways that favored fragmentation of sec,sec-1,2-diols, which produce non-cleavage products. It was observed that IBX can be employed to perform oxidative cleavage of 1,2-diols similar to DMP by simple variation of solvent and temperature. It was also observed that protonation of 10-1-4 species of diols may suppress the nucleophilic attack, leading to the production of ketol to achieve oxidative cleavage of sec,sec-1,2-diols that yield non-cleavage products with IBX in DMSO. TFA was used as a significant source of protons and a better solvent of IBX to conduct protonation of diols. A variety of sec,sec,tert,tert and sec,tert syn-1,2-diols underwent oxidative cleavage effectively, using TFA as a solvent.
- Moorthy, Jarugu Narasimha,Singhal, Nidhi,Senapati, Kalyan
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p. 767 - 771
(2008/03/27)
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- Oxidative cleavage of alkenes catalyzed by a water/organic soluble manganese porphyrin complex
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Tetrakis(4-hydroxyphenyl)porphyrin [TPP-(OH)4] was modified with poly(ethylene glycol) chain as four side arms, such that this compound is soluble in both organic and water solutions. Complexation of this porphyrin with manganese metal ions resulted in the formation of MnCl-TPP-(PEO750)4. This complex proved to be an excellent catalyst for the oxidative cleavage of C{double bond, long}C bonds, yielding the corresponding carbonyl compounds with sodium periodate as an oxidant. Mechanistic pathway for this cleavage is discussed.
- Liu, Shiuh-Tzung,Reddy, K. Venugopal,Lai, Rung-Yi
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p. 1821 - 1825
(2007/10/03)
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- Synthesis of 13C1-pinonaldehyde
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13C1-pinonaldehyde is prepared in seven steps from cis-pinonic acid. In the key sequence, the introduction of labeled carbon is accomplished by Lieben degradation of a methyl ketone followed by treatment of the resultant carboxylic a
- Dicus, Christopher W.,Willenbring, Dan,Nantz, Michael H.
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p. 223 - 229
(2007/10/03)
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- Identification of products containing -COOH, -OH, and -C=O in atmospheric oxidation of hydrocarbons
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Atmospheric oxidation of hydrocarbons by hydroxyl radicals and ozone leads to products containing -COOH, -OH, and -C=O functional groups. The high polarity of such compounds precludes direct GC-MS analysis. In addition, many such compounds often exist in a single sample at trace levels. An analytical method has been developed to identify compounds containing one or more functional groups of carbonyl, carboxy, and hydroxy in atmospheric samples. In the method, -C=O groups are derivatized using O-(2,3,4,5,6- pentafluorobenzyl) hydroxy amine (PFBHA), and -COOH and -OH groups are derivatized using a silylation reagent N,O-bis(trimethylsilyl)- trifluoroacetamide (BSTFA). The derivatives are easily resolved by a GC column. The chemical ionization mass spectra of these derivatives exhibit several pseudomolecular ions, allowing unambiguous determination of molecular weights. Functional group identification is accomplished by monitoring the ions in the electron ionization mass spectra that are characteristic of each functional group derivative: m/z 181 for carbonyl and m/z 73 and 75 for carboxyl and hydroxy groups. The method is used to identify products in laboratory studies of ozone oxidation of α-pinene and Δ3-carene. Among products from ozone oxidation of α-pinene, we have detected pinonaldehyde, norpinonaldehyde, pinonic acid, norpinonic acid, C10 hydroxy dicarbonyls, pinic acid, 2,2-dimethyl-3-(formylmethyl)-cyclobutane-formic acid, and a product that has a molecular weight of 156 and contains a C=O and a COOH/OH group. The latter two products have not been reported previously. Δ3- Carene is structurally analogous to α-pinene in that both have an internal unsaturated bond where ozone oxidation takes place. We have also identified the corresponding analogous products, of which all but caronaldehyde are reported for the first time. An analytical method was developed to identify compounds containing one or more functional groups of carbonyl, carboxyl and hydroxyl in atmospheric samples. -C-to-O double bond groups are derivatized using 0-(2,3,4,5,6-pentafluorobenzyl)hydroxyl amine, and -COOH and -OH groups are derivatized using a silylation reagent N,O-bis(trimethylsilyl)-trifluoroacetamide. The derivatives are resolved using a gas chromatography column coupled with mass spectrometry. The method identified products in laboratory studies of ozone oxidation of α-pinene and Δ3-carene.
- Yu, Jianzhen,Flagan, Richard C.,Seinfeld, John H.
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p. 2357 - 2370
(2007/10/03)
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- Qualitative determination of the non-volatile reaction products of the α-pinene reaction with hydroxyl radicals
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This work describes the qualitative determination of the non-volatile reaction products (condensables) in the α-pinene/OH/O2/NO reaction.The study was carried out in a fast-flow reactor and the hydroxyl radicals were generated by the H + NO2-reaction.Two collection systems have been checked: a liquid nitrogen trap and an active charcoal trap.It was found that the liquid nitrogen trap was the most suitable technique since heterogenous reactions on the active charcoal surface lead to the formation of products not related to α-pinene/OH reaction.Both dichlorometane and methanol have been tried out as solvents but methanol has to be avoided since it forms a number of unwanted methanol-adducts during the extraction or analysis.The following condensables have been identified as genuine reaction products: pinonaldehyde, campholene aldehyde, trans- and cis-pinocamphone, pinol, trans-carveol, carvotaneacetone, trans-sobrerol and a ketoalcohol 5-(2-hydroxy-2-propyl)-2-methyl-2-cyclohexen-1-one.Some mechanistic aspects of the formation of these products are discussed with special attention for the role of nitric oxide.
- Vinckier, C.,Compernolle, F.,Saleh, A. M.
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p. 501 - 514
(2007/10/03)
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- Highly chemoselective reduction of aldehyde function catalyzed by polymer-bound Rh6 cluster complex under water-gas shift reaction conditions
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A functionalized polymer-bound Rh6 cluster complex showed high catalytic activity for chemoselective reduction of aldehydes in the presence of CO and H2O. The reaction system consists of the triphase, which makes work-up procedure simple.
- Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 3005 - 3008
(2007/10/03)
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- Products and mechanism of the gas-phase reaction of NO3 radicals with α-pinene
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The gas-phase reaction of NO3 radicals with a-pinene has been studied under flow conditions in the pressure range 20 2 + NO RO NO2, the following product yields were obtained at p = 200 mbar and [O2] > 1017 molecule cm-3, pinonaldehyde 75 ±6%, a-pinene oxide 15 ±3%, organic nitrates (total) 14 ±3%, a-campholene aldehyde 3 ±1%. In the absence of NO, nitroperoxy-group-containing substances were observed, arising from the reaction RO2 + NO2 -RO2NO2. A reaction mechanism is proposed and a tropospheric application of the results is discussed.
- Berndt, Torsten,Boege, Olaf
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p. 3021 - 3027
(2007/10/03)
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- SELECTIVE REDUCTION OF ALDEHYDES IN PRESENCE OF A KETONE WITH CHLOROTRIMETHYLSILANE AND NICKEL BORIDE
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It has been shown that a combination of chlorotrimethylsilane and nickel boride effects the chemoselective reduction of an aldehyde in presence of a ketonic carbonyl group.
- Borbaruah, M.,Barua, N. C.,Sharma, R. P.
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p. 5741 - 5742
(2007/10/02)
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