Study On Atmospheric Oxidation Mechanism Of Furan Compounds And Terpene

Furan compounds and alkenes play an important role in the atmospheric environment an--d are an important part of atmospheric pollutants.Furan compounds which are mainly deriv--ed from some biomass undergoes a series of chemical reactions after being released into the atmosphere,resulting in an increase in ozone concentration in the atmosphere and contrib--uting to the generation of SOA,etc.,which cause damage to the environment;There are ma--ny sources and types of alkens emitted into the atmosphere,including isoprene and some mo noterpenes,which are prone to some oxidation reactions in the atmosphere,generating pe--roxides,aldehydes,etc,which are the precursors of PM2.5.Therefore,understanding their reaction mechanism in the atmosphere is very important for the planned prevention and cont--rol of these pollutants.The second chapter of this paper mainly combines quantum chemistry and chemical kinetics to further study the reaction process between furan compounds and hy-droxyl radicals.The main method of RHF-UCC SD?T?-F12a/cc-pVDZ-F12 combing with tra--nsition state theory and RRKM theory,calculated the branching ratio,reaction rate and yield of each pathway during the reaction,and compared with some experimental values.The third part of the article explores the reaction process of monoterpene and ozone.There are many la--boratories have investigated the reaction between monoterpene and ozone,focusing on aeros--ol products and the formation of SOA components.This article mainly explores the gas phase reaction products of monoterpene and ozone after a short reaction time,and proposes the corr--esponding reaction mechanism.The main results are as follows:?1?The reaction of furan and its derivatives with hydroxyl groups.The atmospheric oxidation mechanism of furan and methylfurans?MFs?Initiated by OH radicals is studied using high-level quantum chemistry and kinetic calculations.The reaction starts mainly with OH addition to the C2/C5-position,forming highly chemically activated adduct radical R2*/R5*,which would either be stabilized by collision or promptly isomerize to R2B*/R5B*by breaking the C2-O/C5-O bond and then isomerize to other conformers of R2B/R5B by internal rotations.Under the atmospheric conditions,the ring-retaining radical R2/R5 would recombine with O₂ and be converted to a5-hydroxy-2-furanone compound and a compound containing epoxide,ester,and carbonyl functional groups,while the ring-opening radicals R2B/R5B would react with O₂ and form unsaturated 1,4-dicarbonyl compounds.RRKM-ME calculations on the fate of R2*/R5*from the addition of OH and furans predict that the fractions of R2B/R5B formation,i.e.,the molar yields of the corresponding dicarbonyl compounds,are 0.73,0.43,0.26,0.07,and 0.28 for furan,2-MF,3-MF,2,3-DMF,and 2,5-DMF,respectively,at 298 K and 760 Torr when using the RHF-UCCSD?T?-F12a/cc-pVDZ-F12 reaction energies and barrier heights.The predicted yields for dicarbonyl compounds agree reasonably with recent experimental measurements.Calculations here also suggest high yields of ring-retaining 5-hydroxy-2-furanone compounds,which might deserve further study.?2?The experiment investigated the reaction of monoterpenes and ozone.The main purpose of the experiment was to explore the main products of?-pinene and ozone passing through the primary reaction in the gas phase and to propose the corresponding reaction mechanism.We simulated the reaction of ozone and monoterpene in the flow reaction tube.By controlling the flow rate and the volume of the reaction vessel,the reaction time was controlled at about 10 seconds.The product was frozen with liquid nitrogen,and the collected product was dissolved with tetrahydrofuran and cooled to normal temperature,MS-MS detection was performed.Finally,reaction products with mass/charge ratio m/z=197,216,239,and 285 were obtained.The mass spectrum was compared with the molecular weight to obtain the molecular formula of each peak product.The molecular formula of the product is C₈H₁₄O₄,C₁₀H₁₄O₅,C₁₀H₁₆O₅,C₁₁H₁₈O₇,etc.,and the structural formula of the product is obtained through the secondary mass spectrum of each peak product,and compared with the existing data,the formation mechanism of the individual products is proposed.