The Experts below are selected from a list of 510 Experts worldwide ranked by ideXlab platform
Nathan F Dalleska - One of the best experts on this subject based on the ideXlab platform.
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effect of no x level on secondary organic aerosol soa formation from the photooxidation of terpenes
Atmospheric Chemistry and Physics, 2007Co-Authors: P S Chhabra, Arthur W H Chan, Jason D Surratt, Jesse H Kroll, A J Kwan, D C Mccabe, P O Wennberg, Armin Sorooshian, S M Murphy, Nathan F DalleskaAbstract:Secondary organic aerosol (SOA) formation from the photooxidation of one monoterpene (α-pinene) and two sesquiterpenes (Longifolene and aromadendrene) is investigated in the Caltech environmental chambers. The effect of NOx on SOA formation for these biogenic hydrocarbons is evaluated by performing photooxidation experiments under varying NOx conditions. The NOx dependence of α-pinene SOA formation follows the same trend as that observed previously for a number of SOA precursors, including isoprene, in which SOA yield (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted) decreases as NOx level increases. The NOx dependence of SOA yield for the sesquiterpenes, Longifolene and aromadendrene, however, differs from that determined for isoprene and α-pinene; the aerosol yield under high-NOx conditions substantially exceeds that under low-NOx conditions. The reversal of the NOx dependence of SOA formation for the sesquiterpenes is consistent with formation of relatively low-volatility organic nitrates, and/or the isomerization of large alkoxy radicals leading to less volatile products. Analysis of the aerosol chemical composition for Longifolene confirms the presence of organic nitrates under high-NOx conditions. Consequently the formation of SOA from certain biogenic hydrocarbons such as sesquiterpenes (and possibly large anthropogenic hydrocarbons as well) may be more efficient in polluted air.
Alex G Fallis - One of the best experts on this subject based on the ideXlab platform.
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cycloaddition routes to tricyclo 5 4 01 7 02 9 undecanes a direct total synthesis of Longifolene via an intramolecular diels alder strategy
Journal of Organic Chemistry, 1993Co-Authors: Bo Lei, Alex G FallisAbstract:The total synthesis of the sesquiterpene (+)-Longifolene (1) by an intramolecular Diels-Alder cycloaddition strategy is described. Addition of methyllithium to the epoxyfulvene 13, derived from cyclopentadiene and 3,4-epoxy-2-butanone, led to an exo-tet cyclization of the resulting cyclopentadienyl anion to generate the spiro[2.4]hepta-4,6-diene alcohol 14. Resolution of this material was effected via its menthyl carbonate derivative 15. Oxidation of the (+)-R-alcohol with active MnO 2 afforded the cyclopropyl aldehyde 16 which was condensed with the anion derived from methyl 3-methylcrotonate in the presence of cadmium chloride to generate an unsaturated lactone or an unsaturated ester
P S Chhabra - One of the best experts on this subject based on the ideXlab platform.
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188 Chapter 7 Effect of NOx on Secondary Organic Aerosol (SOA) Formation from Photooxidation of Terpenes * This chapter is prepared for journal submission as “Effect of NOx on secondary organic aerosol (SOA)
2014Co-Authors: P S Chhabra, Arthur W H Chan, Jason D Surratt, J. H. SeinfeldAbstract:Secondary organic aerosol (SOA) formation from the photooxidation of one monoterpene (α-pinene) and two sesquiterpenes (Longifolene and aromadendrene) is investigated in the Caltech environmental chambers. By performing photooxidation experiments under varying NOx conditions, the effect of NOx on SOA formation for these biogenic hydrocarbons is evaluated. The NOx dependence of α-pinene SOA formation follows the same trend as that of isoprene (Kroll et al., 2006), in which SOA yield (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted) decreases as NOx level increases. The NOx dependence of SOA yield for the sesquiterpenes, Longifolene and aromadendrene, however, differs from that determined for isoprene and α-pinene; the aerosol yield under high-NOx conditions substantially exceeds that under low-NOx conditions. The reversal of the NOx dependence of SOA formation for the sesquiterpenes is consistent with formation of relatively nonvolatile organic nitrates, and/or the isomerization of large alkoxy radicals that leads to less volatile products. Analysis of the aerosol chemical composition fo
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effect of no x level on secondary organic aerosol soa formation from the photooxidation of terpenes
Atmospheric Chemistry and Physics, 2007Co-Authors: P S Chhabra, Arthur W H Chan, Jason D Surratt, Jesse H Kroll, A J Kwan, D C Mccabe, P O Wennberg, Armin Sorooshian, S M Murphy, Nathan F DalleskaAbstract:Secondary organic aerosol (SOA) formation from the photooxidation of one monoterpene (α-pinene) and two sesquiterpenes (Longifolene and aromadendrene) is investigated in the Caltech environmental chambers. The effect of NOx on SOA formation for these biogenic hydrocarbons is evaluated by performing photooxidation experiments under varying NOx conditions. The NOx dependence of α-pinene SOA formation follows the same trend as that observed previously for a number of SOA precursors, including isoprene, in which SOA yield (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted) decreases as NOx level increases. The NOx dependence of SOA yield for the sesquiterpenes, Longifolene and aromadendrene, however, differs from that determined for isoprene and α-pinene; the aerosol yield under high-NOx conditions substantially exceeds that under low-NOx conditions. The reversal of the NOx dependence of SOA formation for the sesquiterpenes is consistent with formation of relatively low-volatility organic nitrates, and/or the isomerization of large alkoxy radicals leading to less volatile products. Analysis of the aerosol chemical composition for Longifolene confirms the presence of organic nitrates under high-NOx conditions. Consequently the formation of SOA from certain biogenic hydrocarbons such as sesquiterpenes (and possibly large anthropogenic hydrocarbons as well) may be more efficient in polluted air.
Aziz Bicer - One of the best experts on this subject based on the ideXlab platform.
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Analiza kemijskog sastava katrana od libanonskog cedra
'Faculty of Forestry University of Zagreb', 2017Co-Authors: Ayben Kilic Pekgozlu, Suleyman Kustas, Burak Mercan, Aziz BicerAbstract:Chemical characterization of Cedrus libani A. Rich tar, obtained by the traditional method and Jenkner Retort, was studied. Roots and fallen branches were used and analyzed separately. FID-GC and GC-MS were used for the characterization. The tar yield of Jenkner Retort was 60 %, while it is 30-40 % in the traditional method. 41 compounds were identifi ed. β-himachalane (22-28 %) was found to be the main compound in all tars. α-himachalane (6-10%) and Longifolene (7-9 %) were the other important compounds. Some compounds, which have antifungal and insecticides effects like deodarone and E-(α)-atlantone, were determined only in tars of roots. Phenolic compounds were not determined by the traditional method.U radu je prikazana analiza kemijskog sastava katrana od libanonskog cedra (Cedrus libani A. Rich) dobivenoga tradicionalnim postupkom i uz pomoć Jenknerove retorte. Napravljena je zasebna analiza za staro korijenje i za otpale grane libanonskog cedra. Za kemijsku karakterizaciju primijenjene su metode FID-GC i GC-MS. Prinos katrana uz pomoć Jenknerove retorte bio je 60 %, a prinos tradicionalnom metodom iznosio je 30 – 40 %. Pritom je identificiran 41 kemijski spoj. Ustanovljeno je da je β-himakalan (22 – 28 %) glavni spoj svih analiziranih katrana. Drugi po važnosti bili su A-himakalan (6 – 10 %) i longifolen (7 – 9 %). Neki spojevi koji imaju antifungalne i insekticidne učinke kao što su deodaron i E-(α)-atlanton pronađeni su samo u korijenju. U katranu dobivenom tradicionalnim postupkom nisu pronađeni fenolni spojevi
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Chemical characterization of lebonan cedar tar [Analiza kemijskog sastava katrana od libanonskog cedra]
'Faculty of Forestry University of Zagreb', 2017Co-Authors: Ayben Kilic And Kustas, And S. Mercan, Aziz BicerAbstract:Chemical characterization of Cedrus libani A. Rich tar, obtained by the traditional method and Jenkner Retort, was studied. Roots and fallen branches were used and analyzed separately. FID-GC and GC-MS were used for the characterization. The tar yield of Jenkner Retort was 60 %, while it is 30-40 % in the traditional method. 41 compounds were identified. β-himachalane (22-28 %) was found to be the main compound in all tars. α-himachalane (6-10%) and Longifolene (7-9 %) were the other important compounds. Some compounds, which have antifungal and insecticides effects like deodarone and E-(α)-atlantone, were determined only in tars of roots. Phenolic compounds were not determined by the traditional method. © 2017, Journal Drvna Industrija. All rights reserved
Raksh V Jasra - One of the best experts on this subject based on the ideXlab platform.
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solvent free synthesis of 7 isopropyl 1 1 dimethyltetralin by the rearrangement of Longifolene using nano crystalline sulfated zirconia catalyst
Journal of Molecular Catalysis A-chemical, 2009Co-Authors: Beena Tyagi, Manish Mishra, Raksh V JasraAbstract:Abstract Nano-crystalline sulfated zirconia solid acid catalyst, synthesized by a one-step sol–gel method, was studied for the rearrangement of Longifolene to isoLongifolene and 7-isopropyl-1,1-dimethyltetralin under solvent free conditions. Kinetic and 1H NMR spectroscopic studies confirmed the formation of 7-isopropyl-1,1-dimethyltetralin through further rearrangement of isoLongifolene in the presence of a higher number of acidic sites. The selectivity for the rearranged products namely isoLongifolene and 7-isopropyl-1,1-dimethyltetralin was observed to be strongly influenced by the acidity of the catalysts in terms of Bronsted (B) and Lewis (L) acid sites ratio. The catalyst having a higher B/L ratio (5.6) showed higher selectivity (56%) for 7-isopropyl-1,1-dimethyltetralin. The selectivity for the products could also be controlled by Longifolene to catalyst weight ratio; for example, ∼100% isoLongifolene could be obtained using less amount of the catalyst, whereas for 7-isopropyl-1,1-dimethyltetralin higher amount of catalyst was required. Thermally regenerated catalyst showed decreased selectivity for 7-isopropyl-1,1-dimethyltetralin due to a decrease in the B/L ratio, which in turns influenced by loss of sulfur during the reaction.
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solvent free isomerisation of Longifolene with nano crystalline sulphated zirconia
Catalysis Communications, 2006Co-Authors: Beena Tyagi, Manish Mishra, Raksh V JasraAbstract:Abstract Nano-crystalline sulphated zirconia catalyst was synthesised using sol–gel technique in acidic, basic and neutral medium. The samples were characterised by X-ray diffraction, DRIFT spectroscopy, nitrogen adsorption–desorption and TG analysis. Bronsted acidity was measured by cyclohexanol dehydration model reaction. The samples were studied for single step, solvent free isomerisation of Longifolene to iso-Longifolene in a liquid phase batch reactor. The catalyst yielded >90% conversion and ∼100% selectivity for iso-Longifolene.
