Kinetics of stabilised Criegee intermediates derived from alkene ozonolysis

13 Pages·2015·2.19 MB·English

by  Mike J. Newland

PCCP
PAPER View Article Online
View Journal | View Issue
Kinetics of stabilised Criegee intermediates
e.
c derived from alkene ozonolysis: reactions with
n
e
c
2:37:20. ported Li C20it1e5t,h1i7s,:P4h0y7s6.Chem.Chem.Phys., SlaOye2,rHco2Ondaitnidondsecomposition under boundary
1n
7 U
8/201n 3.0 Mike J. Newland,a Andrew R. Rickard,b Mohammed S. Alam,a Luc Vereecken,c
d on 15/0Attributio Amalia Mun˜oz,d Milagros Ro´denasd and William J. Bloss*a
nloademons tTrhaensr-ebmuto-v2a-leonfeSaOn2din2,3th-edimpreetsheynlc-beuot-f2a-lkeennee,–asozaofnuencstyisotnemofshhuamsbideiteyn,ustnuddeierdatfmorosepthheenriec,bcoisu-nbduat-ry2-leayneer,
wm conditions. The SO removal displays a clear dependence on relative humidity for all four alkene–ozone
oo 2
DC
5. ve systemsconfirmingasignificantreactionforstabilisedCriegeeintermediates(SCI)withH2O.Theobserved
201eati SO2removalkineticsareconsistentwithrelativerateconstants,k(SCI+H2O)/k(SCI+SO2),of3.3((cid:2)1.1)(cid:3)
y Cr 10(cid:4)5 for CH OO, 26 ((cid:2)10) (cid:3) 10(cid:4)5 for CH CHOO derived from cis-but-2-ene, 33 ((cid:2)10) (cid:3) 10(cid:4)5
Article. Published on 06 JanuarThis article is licensed under a Received17thSeptember2014, 112UdTifno00,ehn3tre11ric-si11rvdeCpeycircmridHtmeemalt3eidnf(cid:4)a(cid:4)Ctostht33iHiloelyvoflsnOafo-wol,burO2arieunerCxtesgC-pHd2oHle(cid:2)ti2-cfh3rOei2eiCt3vnlsOy.eH5ead,.cpOa(o(cid:2)T1npOf3nhdr3roseo.(i1xddr(cid:2)m)iremeee4(cid:3)prrlai3aritnvettr1)giieas0vo(cid:3)edne(cid:4)ntnhs4rt-1fetarbf0hotocdeua1mor1ittfmc-fkceao2(mStrb-nriCsniaens(cid:4)ignIntne3ags+edrn3-lef,etobHassraucyS2fntstOoCCi-tvdreI2)Hi/tmk-yki38s(e(CSaSf.n7otCpCHiercrIIOe(s(cid:2)d+sayaOeenn2nSncd-.d5Ootda)me26fpno)r(cid:3)3rpdirevooecfa(es1(cid:2)idnsaia0titnic1ooif(cid:4)-4htrnni5So-))CCsm/c(cid:3)fkyIHoo(sSctrmc3eC1oCi0smpn(IHC-1of+;b1oOHnuraecO3mSt)nmO-2met2Ca2s(cid:4)r-on).sO3e,draTenOirsfh1eeo.cea2,ro(cid:4)dlss(cid:4)e(me(o2(cid:2)C1r.pi3v14pHv.rar1ee3(el()(cid:2)ud)h(cid:2)s2(cid:3)eee3C3snfn.51Or1tso))a0eiOvmrd(cid:3)(cid:3)1ee3..
ess Accepted23rdDecember2014 for k(SCI decomposition)/k(SCI + SO2) of syn-CH3CHOO. The reaction of the water dimer with CH2OO is
Acc DOI:10.1039/c4cp04186k also considered, with a derived value for k(CH2OO + (H2O)2)/k(CH2OO + SO2) of 1.4 ((cid:2)1.8) (cid:3) 10(cid:4)2.
n The observed SO removal rate constants, which technically represent upper limits, are consistent with
e 2
p
O www.rsc.org/pccp decompositionbeingasignificant,structuredependent,sinkintheatmosphereforsyn-SCI.
1. Introduction a boreal forest have identified the presence of an additional
oxidant species, removing SO and producing H SO . The
2 2 4
Atmosphericoxidationprocessesarecentraltounderstandingtrace additionalSO oxidationobservedwassubstantial(comparable
2
gas atmospheric composition, the abundance of air pollutants tothatduetoOHradicalsalone),andattributedtoaproductof
harmfultohumanhealth,cropsandecosystems,andtheremoval alkeneozonolysis–theborealforestenvironmentbeingonein
of reactive greenhouse gases such as methane. The principal whichsubstantialbiogenicalkeneemissionsoccur–suggested
atmospheric oxidants responsible for initiating the gas-phase to be the stabilised Criegee intermediate (SCI). The gas-phase
degradationofvolatileorganiccompounds(VOCs),NO andSO oxidation of SO in the atmosphere is of interest to climate
x 2 2
are OH, NO and O , with additional contributions from other researchasitleadstoformationofH SO ,contributingtonew
3 3 2 4
speciessuchashalogenatoms.Recentfieldmeasurements1in particleformationandsulphateaerosolloading,incompetition
withcondensedphaseoxidation.2Amissingmechanismforthe
conversionofSO toH SO couldleadtomodelunderestimation
aUniversityofBirmingham,SchoolofGeography,EarthandEnvironmental 2 2 4
of the sulphate aerosol burden and affect radiative forcing
Sciences,Birmingham,UK.E-mail:[email protected]
bWolfsonAtmosphericChemistryLaboratories,DepartmentofChemistry, calculations,3 with corresponding implications for climate pre-
UniversityofYork,York,UKandNationalCentreforAtmosphericScience, dictions.EnhancedSO oxidationinalkene–ozonesystemswas
2
UniversityofYork,York,UK first reported by Cox & Penkett4 over forty years ago, however
cMaxPlanckInstituteforChemistry,AtmosphericSciences,J.-J.-Becher-Weg27,
theprecisereactionmechanismgivingrisetothiseffectremains
Mainz,Belgium
dInstitutoUniversitarioCEAM-UMH,EUPHORELaboratories, elusive.The‘‘Criegee’’ozonolysisreactionmechanismwasfirst
Avda/CharlesR.Darwin.ParqueTecnologico,Valencia,Spain postulated in the 1940s.5 It is now accepted that the ozone
4076 | Phys.Chem.Chem.Phys.,2015,17,4076--4088 Thisjournalis©theOwnerSocieties2015
View Article Online
Paper PCCP
suggestingthatbimolecularreactionwithSCIsisanunimportant
oxidationmechanismfortracegasspecies.Thisviewwasrecently
challenged by direct observation14 and kinetic studies15–17 of
theCH OOandCH CHOOSCIs.
2 3
Taatjes and co-workers,15 directly observing CI kinetics for
thefirsttime,foundreactionsofCH OOwithSO andNO to
2 2 2
be substantially faster than previously thought, pointing to a
potentially important role for this species in atmospheric SO
2
e. andNO2oxidation;subsequentmeasurementshaveidentified
c
n SO (ref. 16) and NO (ref. 18) as products of these reactions.
e 3 3
c
20. d Li ThekeytowhetherSCIsareindeedsignificantcontributorsto
2:37:porte gcoans-spthanastsefaotrmreoascpthioenricofStOh2eSoCxiIdwatitiohnSOis (tkhe),rtaotitohaotfwtihtheHratOe
1n 2 2 2
8/2017 n 3.0 U (wke3)reanpdroddueccoemdpboystihtieon24(8kdn).mInlalasebrorpahtoortyolsytsuisdioefsawlkhyelreioSdCidIes
0o
wnloaded on 15/mmons Attributi (SScChIes)mfoer1meSdimfropmlifieadlkmeneechoaznoinsmolyfsoisr.thereactionofCriegeeIntermediates 1pbttwh0yrieo(cid:4)scV1urS1UaCrcVtsIimoosrp3sh(hCasaoH(cid:4)stt1or24eOiaocTnOneodn1irs5trak,l1ytt7iobooatneanneldntipnhrCreeetHsphos3oreuCdrrtHpeeerr,dOewosOtfeiot1n1h6b0c)e,et(cid:4)hw11oe50ift3Sch–mCe1xkI03c24desosef(cid:4)osnc1ra.cyttIohhnm-eerecosoaomnrcndittataeorlnrlareetsosstdtf,,
oo 3
5. Dve C molecule adds to the CQC double bond via a concerted cyclo- alternative studies of SO2 oxidation in alkene–ozone systems,
201eati additiontoformaprimaryozonide,followedbycleavageoftheC–C performed at atmospheric pressure through detection of the
ublished on 06 January e is licensed under a Cr bcSclaoahmConrenIbogsmdonlaniiagcrfnyseealttdlifloomyootxrhaniemdcesetereiot,vdsofapotwturehencide‘tiCdheOaresina.r–egCOdgbohersbeobetoamaiimnbdniditcoliesianlsrelfemtloceydurreamnlSdcaaCitrialinIvrtsegaee.nt’aaSeec(dCrcCtgiaIIoSysr)Cn.b6dcsoIaisOnswnmtyzrilohtiahbmnayuvoHoaetlilyl2oesssOocnuisu,fuafltdeinnoceddaireyneiniSvredOegtllddoay2 mf(sd(HbSrtioa2OsyuSmbclZcOrtiai)lepi4o.psaltteaephdwdnrdeSoocrCuaydoocIturtxmcdaciofdettao,nmrayrsfnfmooiiotnrnsefmpsdcdmphleuemefradcrrsgiouieecnwmcsithi,pthtuhfrteosdehdmrseelmsii)ffa.uSef1eler9tCldeierEmIi,rw2nx0+egpSitClehrSoafeIOifnfnaea2+ctchttttihrisSeoveeOinaotscosy2eft,zcfirootoooahrnnrnteoec,tdholacpycniorsrsoytielreslasiifopsbesfzinipyuocosactintnieereoaenimdnlnotlesysft,
Article. PThis articl ctsihoolinlfits(iSroecnaharerlmasnteagb1e)im.liFseaontrtiostunhb,rsoutunitgiumhteoadleavcilunkleyanlr-hedsye,dcSroCompIseprcooasxniitdiuoennd(VoeHrrgiPso)oamvi1ae,r4it-shHae-- taolkeSnOe2–SrOea2ctsiyosnt.emUnidnetrhsteanpdriensgentcheeobfewhaatveirouvrapoofurthies corziotincea–l
s to quantifying the impact of SCI chemistry upon atmospheric
es so-called‘‘hydroperoxidechannel’’anddecomposetoyieldOHand
Acc a vinoxy radical – a substantial non-photolytic source of atmo- SO2oxidation.21
en sphericoxidants.7,8ThisisthefavouredchannelforSCIsformed Anadditional,potentiallyimportant,fateofSCIunderatmo-
Op in the syn-configuration. Time resolved studies9 show that the spheric conditions is unimolecular decomposition (denoted
k in(R4)). ForCH OO,rearrangement viaa ‘hot’acidspecies
VHPmaypersistforappreciabletimescalesunderboundarylayer d 2
represents the lowest accessible decomposition channel, but
conditions,givingrisetotheobservedpressuredependenceofOH
radical yields,10 and opening the possibility for bimolecular due to lack of alkyl substituents, the theoretically predicted
298 K rate constant is rather low, 0.3 s(cid:4)1.22 Previous studies
reactions of this species to occur. SCIs formed in the anti-
haveidentifiedthehydroperoxiderearrangementasdominant
configurationarethoughttoprimarilyundergorearrangement
for SCIs with a syn configuration, determining their overall
and decomposition via a dioxirane intermediate (‘‘the acid/
unimolecular decomposition rate.7,8 For syn-CH CHOO recent
ester channel’’), producing a range of daughter products and 3
contributingtotheobservedoverallHO radicalyield.6,11 experimental23workyieldedadecompositionrateof3–30s(cid:4)1.
x Theoreticalwork24haspredictedadecompositionratecoefficient
AlkeneþO3 (cid:2)k!1 fSCIþð1(cid:4)fÞCIþRCHO (R1) of 24.2 s(cid:4)1 for syn-CH3CHOO and 67.2 s(cid:4)1 for anti-CH3CHOO
(forwhichonlytheesterchannelexists),owingtothepotential
SCIþSO2 (cid:2)k!2 SO3þRCHO (R2) elinmeirtgytoretoletaasleCfHromCHthOeOhliogshser(deenceormgypaonsitti-icoonnafonrdmheer.t2e3roAgnenuepopuesr
3
walllossescombined)ofo250s(cid:4)1hasbeenreportedbyTaatjes
SCIþH2O (cid:2)k!3 products (R3) et al.16 Earlier experimental work reported decomposition rate
constants of r20 s(cid:4)1 for CH CHOO derived from cis-but-2-ene
3
SCI k!d products (R4) ozonolysis,25 and 76 s(cid:4)1 (accurate to within a factor of three)
(cid:2) for CH CHOO derived from trans-but-2-ene ozonolysis.26 For
3
Until recently, it has been thought that the predominant (CH ) COO (derived from 2,3-dimethyl-but-2-ene ozonolysis) a
32
atmospheric fate for SCIs was reaction with water vapour12,13 – total loss rate of 3.0 s(cid:4)1 has recently been determined experi-
leadingtoasignificantsourceoforganicacidsandhydroperoxides, mentally.19Thisvalue(whichrepresentsanupperlimitfork )
d
Thisjournalis©theOwnerSocieties2015 Phys.Chem.Chem.Phys.,2015,17,4076--4088 | 4077
View Article Online
PCCP Paper
is somewhat smaller than but comparable in magnitude to an therange1.5–21%RH.Measuredincreasesin[SO ]agreedwith
2
earliermeasurementof6.4s(cid:4)1(determinedat100Torr).27Theore- measured volumetric addition across the SO and humidity
2
ticalestimatesof(CH)COOdecompositionratesarehigher,atup rangeusedintheexperiments.
32
to250s(cid:4)1.22Photolysislossrateshavealsorecentlybeenreported
for CHOO28 and CHCHOO29 of 1 s(cid:4)1 and 0.2 s(cid:4)1 respectively, 2.3 Analysisapproach
2 3
calculatedforactinicfluxvaluesatmidday,SZA=01. The following sections describe (i) a common analysis applied
Here,wepresentresultsofaseriesofexperimentsinwhich to all systems, but which features several approximations, and
theoxidationofSO duringtheozonolysisofethene,cis-but-2-ene, (ii)moredetailedconsiderationofeachchemicalsysteminturn,
2
e. trans-but-2-ene and 2,3-dimethyl-but-2-ene (tetramethylethylene, to address potential contributions from the water dimer, and
c
n TME), was investigated in the presence of varying amounts of multiple criegee species within each system (e.g. contrasting
e
c
20. d Li waterintheEuropeanPhotochemicalReactorfacility(EUPHORE), reactivityofdifferentSCIconformers).
2:37:porte Valencia,Spain. assFurmomedtthheatcShCemI wisitlrlybperepsreondtuecdedininretahcetiocnhsam(Rb1e)r–(fRro4m) itthies
1n
8/2017 n 3.0 U 2. Experimental rperaocdtuiocnedocfatnhethaelnkerneaecwtiwthithozSoOn2e,waitthaHgi2vOen,wyiitehldo,thfe.rTshpeecSiCesI
0o
wnloaded on 15/mmons Attributi rt2Eie.oU1anPcstHi.EoOInUnRPmgEHeenOicsehRraaaEnl2,i0sem0xpsmeru3imnsdiemenrtusalatcmtoimoonspprchihseeardimctbibmeorue-nuredsseaodrlyvfeoladryemsrtuecadosynuidnreig-- orSpwaCrrhtoIedic,ceaehicsstosrwdmeeehsapticeocotrfhssmetSwhiOuneitn2ehSddiCseSbIrOloy(t2esht,qthe,cnecoeom(fxErmpap1ecp)art)air:imeroedned,ntwfot,aiottlhhfceotthhnseeudmitttooitotaoanllfspStahCropeIdpptuloirceottaddilo.unlTcohesodesf
2015. Doeative Co smmyseetnaestmuor,feadtsheuasrfienumgncoctvioaonlnvoeofnfSthiOou2nmainlidftilhtuyeo.rpSeOrsec2seeannnccedeaOonf3daanbUuaVnlkdaeabnnseco–eropzwtoieonrnee f ¼k2½SO2(cid:5)þkk23½½SHO2O2(cid:5)(cid:5)þkdþL (E1)
y Cr
ublished on 06 Januare is licensed under a wdTtFmoTeheovIreenReinaictts0shoiu.pora2rsnem5e,cstbrarroaeoenfpssrdpcitdhioes0cpem.t4yfimi.v7itextTeelipyanhdp;sgebuwav(rpltiekrhtrdeheerncesvileepsaaielromaucgnbteeiiunvophenufrlodytieortahis(rnze)eco.tveoanFSltOuuSwarOa2latth2seaadennodrrddeadOtsvOee3ert23rmaatimidslicsntdaaoeiolnntdfidifotaatovnhnrri)daess. pnreogHcleeecsrtsese,soLtfhoiserrtSh(CneIosinun-matlhkoeefncahen)adydcmShOoObte3hem2re¼,ircapafflstees(cid:6)ruifncdkoosr-rffieorcsrttiOoonr,dfseourrccdhhileaumstiriocen(aaE.lc2t(liEo)os2ns)
s Article. P This articl chEhxopaumesribnimegrecnsletotssuewpdea;rnej(dNpieOnr2fso)trrrummed1en0i(cid:4)tna6ttihso(cid:4)ne1d)a,raeraktav(aait.ieml.aobwsliepthheletsrheiecwhcpherraeems.s3ub0,re3e1r lwionisdtshicuaHnteOdd2ert–haralollsutoghhpermeoxdopudecereilmdcaedlncirutealcalttcliyoonndsduitrtoiinoagncscaolokufenntthe3fiosorzwooonr2ok%l.ysEoisqf,no11z(obEnu1et)
s
cce (ca. 1000 mbar) and temperatures between 296 and 303 K, on and(E2)treattheSCIsformedasasinglespecies–thisisthe
A timescalesofca.20–30minutes.Chamberdilutionwasmonitored
n casefor(e.g.)etheneandTME,butisanapproximationforthe
Ope viathefirstorderdecayofanaliquotofSF6,addedpriortoeach 2-butenes;consideredfurtherbelow.
experiment.Cyclohexane(ca.75ppmv)wasaddedatthebeginning
2.3.1 SCIyieldcalculation.Valuesforf weredetermined
SCI
of each experiment to act as an OH scavenger, such that SO
2 foreachozonolysisreactionfromexperimentsperformedunder
reactionwithOHwascalculatedtober1%ofthetotalchemical dry conditions (RH o 1%) in the presence of excess SO
2
SO removalinallexperiments.
2 (ca. 1000 ppbv), such that SO scavenges the overwhelming
2
majority of the SCI. From eqn (E2), regressing dSO against
2
2.2 Experimentalapproach
dO (corrected for chamber dilution), assuming f to be unity
3
Experimental procedure, startingwiththe chamberfilled with (i.e.alltheSCIproducedreactswithSO )determinesthevalueof
2
cleanair,comprisedadditionofSF andcyclohexane,followed f ,alowerlimittotheSCIyield.Fig.2showstheexperimental
6 min
bywatervapour,O (ca.500ppbv)andSO (ca.50ppbv).Agap data,fromwhichf wasderived,forallfouralkeneozonolysis
3 2 min
offiveminuteswasleftpriortoadditionofthealkene,toallow systemsstudied.
completemixing.Thereactionwastheninitiatedbyadditionof The lower limit criterion applies as in reality f will be less
thealkene(ca.500ppbvforethene,200ppbvforcis-andtrans- than one, at experimentally accessible SO levels, as a small
2
but-2-eneand400ppbvforTME).Thechamberwasmonitored fraction of the SCI will still react with any H O present, or
2
foranhoursubsequenttotheadditionofetheneandfortyfive undergodecomposition.Theactualyield,f,wasdeterminedby
minutesforcis-andtrans-but-2-eneandTME.Therateofalkene– combiningtheresultsfromthehigh-SO experimentswiththose
2
ozone consumption is dependent on k . Roughly 25% of the from the series of experiments performed at lower SO , as a
1 2
ethenewasconsumedafteranhour,whileforcis-andtrans-but-2- functionof[H O],todeterminek /k andk /k (seeSection2.3.2),
2 3 2 d 2
eneandTME90%ofthealkenewasconsumedwithinroughly throughaniterativeprocesstodeterminethesingleuniquevalueof
25 minutes, 20 minutes and 6 minutes respectively. Each f whichfitsbothdatasets.ItisimportanttonotethattheSCI
SCI
experiment was performed at a constant humidity, which was yieldistoanextentanoperationallydefinedquantity–forexample,
increased in a step-wise manner for consecutive runs to cover OHformationfromalkeneozonolysisisknowntoproceedover
4078 | Phys.Chem.Chem.Phys.,2015,17,4076--4088 Thisjournalis©theOwnerSocieties2015
View Article Online
Paper PCCP
atleasthundredsofmilliseconds9followingthealkene–ozone
reaction,andsothecorrespondingCIpopulationmustalsobe
evolvingwithtime.Inthiswork,SCIyieldsreflecttheamountof
SCIavailabletooxidiseSO ontimescalesofsecondstominutes.
2
2.3.2 k(SCI + H O)/k(SCI + SO ) and k /k(SCI + SO ). To
2 2 d 2
determine k /k and k /k , a series of experiments were per-
3 2 d 2
formedforeachalkene,inwhichtheSO losswasmonitoredas
2
a function of [H O]. From eqn (E2), regression of the loss of
2
e. ozone (dO3) against the loss of SO2 (dSO2) (both corrected for
c
n dilution,measuredthroughtheremovalSF ,addedatthestart
e 6
c
20. d Li ofeachexperimentandmonitoredviaFTIR)foranexperiment
2:37:porte wdeiltlervmariynetshtrhoeugfahcttohref(cid:6)fexaptearigmiveenntpaosinStOintiismceo.nTshuimsqeuda,natnitdy
1n 2
8/2017 n 3.0 U oeqthner(Ep1o).teAntsimaloSoCthIecdo-frietawctaasnatsppalrieedprtoodtuhceedex,paesripmreednitcatleddabtay Fmigin.i2mumDSOSC2Ivysi.eDldOf3odrutrhinegfothueraelxkceensessS.O2experiments,todeterminethe
0o
wnloaded on 15/mmons Attributi f(emtFooairecgtnhht.hte1ee()gix.cpretueo.eamrwtdiemhueseltetaenntrriamt[vS,teeOifncoo2eor]fnBdupsSsrueoO5md02iu/nppdctpOietoibq3onvnn()oaw(onfEfadS3stO)hh.u2eeTsaneShncdCedeIa,sOfst(cid:6)aaf3tn,rh)dtDiasoShtfcOetonth2rhceraeeensseldtpaaxorDprgnteOedros3istf-, tsChyHset3eCcmaHssOetOfhoirSsCtihIse(aseynnthaeapnnpedroaaxnnimdti)aTtaMioreEnpsarysosdtteuwmcoesd,c.ofonFrfuortrthmheeerbrsuanto-a2fl-yetsnhiees
oo
y 2015. DCreative C aceoxtpmweprhiaimcrehednttwhaelitshSigCanInayl+so(StOhO3e2arnrpedoatScetOnio2tniraalthecahosefmtchhiecaanglgrleeo)asatsenspdtriomscteahsgesnepistoufidnoert edisnifpefeesrryefsontretmmSeCsdIi.sintrSeeactteidonas3h.3a.v2iningwtwhoicchotmhepoSnOe2nltoss,sreinlatthedebtoutt-h2e-
ublished on 06 Januare is licensed under a eitherspecies(½sSeOe2d(cid:5)(cid:3)isc1fu(cid:4)ss1io(cid:4)n¼bekkl32o½wH)2.O(cid:5)þkdkþ2 L (E3) 33Tet.ah1.belneReI1n,ecstirhsso-obduwuusltc-tt2thsi-eoennraee,snturaldtnins-gdbuSiCts-2Ic-yeiuneledsassnoidbottaenitnraemdefothrytlheethoyzleonneol(yTsMisEo)f;
s Article. P This articl finorteTerhacceehpvtaelxoupfee(r[kSidmO+e2]n(L(t1)t//okf)2g(cid:4)(ive1eq)nacpa(Enlo3tt)h)w.einOthubaregdreraagtdraeiescsnaentdonfaogkta3d/ikne2stetarn[mHd2ianOne] u(Aenlssctoiemrstahatioenwdtinemsaeaarerseupr(cid:2)eams2tse,lnittaenurdantcurerereptarivenastleyun)etas,nthdoebptcraeoicnmiesbdioinnuencdodmseyrpstoveanmreinaottuiscs.
s
cce absoluterateconstants(i.e.valuesofk2,k3,kd)inisolation,butis conditionsusingarangeofdifferentSCIscavengers.
A limitedtoassessingtheirrelativevalues,whichmaybeplacedon
Open anabsolutebasisthroughuseofan(external)referencevalue. worTkhiesy0ie.3ld7o((cid:2)fC0.H042O).OThfriosmyieeltdhehnaesobzeoennoilnysviesstoibgtaatiendedininmtahnisy
Eqn(E1)–(E3)aspresentedaboveassumethatonlyasingle
previous studies, with values ranging from 0.34–0.50 deter-
SCIspeciesispresentineachozonolysissystem.Whilethisis mined – a more detailed review is available elsewhere.31 The
yieldobtainedinthisworkisatthelowerendofbutwithinthe
envelopeoftheseestimates,andisinexcellentagreementwith
thecurrentIUPACrecommendationof0.37.
The yield of CH CHOO from cis-but-2-ene ozonolysis
3
obtained in this work is 0.38 ((cid:2)0.05), with that from trans-
but-2-enebeing0.28((cid:2)0.03).Thesevaluesfallwithintherange
ofreportedliteraturevaluesof0.18–0.43and0.13–0.53forcis-
but-2-ene and trans-but-2-ene respectively (Table 1). cis and
trans-but-2-ene both yield (differing) mixtures of syn and anti
conformersofCH CHOO,therelativeamountsofwhicharenot
3
wellknown,andwhicharetreatedhereinitiallyasasingleSCI
species(thisapproximationisdiscussedfurtherinSection3.3).
Berndt et al.32 recently reported a yield of 0.49 ((cid:2)0.22) for the
CH CHOO produced from trans-but-2-ene ozonolysis (also
3
treatingbothsynandanticonformersasasingleSCIspecies).
Fig.1 Cumulative consumption of SO and O , DSO versus DO , for
2 3 2 3 The yield of (CH ) COO from TME ozonolysis obtained in
the ozonolysis of four alkenes in the presence of SO at a range of 32
2 this work is 0.32 ((cid:2)0.02). This again falls within the (wide)
relative humidities from 1.5–21%. Open symbols are experimental data,
corrected for chamber dilution. Solid lines are smoothed fits to the range in the literature of 0.10–0.65, with Berndt et al.32 most
experimentaldata. recentlyreportingayieldof0.45((cid:2)0.20).
Thisjournalis©theOwnerSocieties2015 Phys.Chem.Chem.Phys.,2015,17,4076--4088 | 4079
View Article Online
PCCP Paper
Table 1 SCI yields derived in this work and reported in the literature.
Uncertainty ranges ((cid:2)2s, parentheses) indicate combined precision and
systematicmeasurementerrorcomponentsforthiswork,andaregiven
as stated for literature studies. All referenced studies were conducted
between700and760Torr.C2B–derivedfromcis-but-2-ene;T2B–derived
fromtrans-but-2-ene
SCI j Ref.
SCI
CH OO 0.37((cid:2)0.04) Thiswork
2
0.37 MCMv3.2a(IUPAC)33
e. 0.35((cid:2)0.05) Nikietal.34
c
en 0.39((cid:2)0.053) Hatakeyamaetal.35
20. d Lic 00..4570(((cid:2)(cid:2)00..0054)) HNeoerbieeatnadl.3M7oortgat36
12:37:nporte 00..3594(((cid:2)(cid:2)00..1115)) HAlaasmsoenteatl.a31l.38
7 U
8/201n 3.0 (CCH23BC)HOO 00..1398((cid:2)0.05) RThiciksawrdorektal.39 FCiHg.C3HOAOpp(ldiceartiivoendofrfoemqnci(sE-3b)utto-2d-eernivee;rCat2eBc),oCnHstaCnHtsOfoOr(rdeeacritvieodnforofmCHtr2aOnOs-,
0o 3 3
d on 15/Attributi 00..1483 NCoikxiaentdalP.4e0nkett41 tboutt-h2a-tefnoer;rTea2cBt)i,oanndwi(tChHS3O)22C,Ok3O/k2waitnhdH(2kOd+(k3L))/akn2d–dseeceomtepxto.sition(kd),relative
oadeons (CTH2B3C)HOO 00..4298(((cid:2)(cid:2)00..2023)) BTherinsdwtoertkal.32
wnlmm 0.53((cid:2)0.24) Berndtetal.19 Table2 SCIrelativerateconstantsderivedinthisworkusingthesingle-
DoCo 0.45 CoxandPenkett41 SCIwatermonomerapproach(i.e.eqn(E3);seetext).Uncertaintyranges
5. ve 0.19((cid:2)0.03) Hatakeyamaetal.35 ((cid:2)2s,parentheses)indicatecombinedprecisionandsystematicmeasure-
y 201Creati 00..4224((cid:2)0.07) HHoasriseonanedtaMl.o38ortgat36 menterrorcomponents
ublished on 06 Januare is licensed under a (CH3)2COO 0000c00a......341613.2532000.((((6(cid:2)(cid:2)(cid:2)(cid:2)50000b....22000832)))) BBHRNTDheeiirackrroisknnsizsadddoewrtttndoeaeetreettlkta.t4aala0a.ll1..ll31.0.329389 C(CSCCCHHHHI2333OCC)2HHOCOOOOOO((CT22BB)) 23183630..735(((((cid:2)(cid:2)k(cid:2)(cid:2)311/21k00..2))51)) 611(cid:4)(cid:4)33012(cid:4)4.((31(cid:2)(cid:2)1((14(cid:2)(cid:2)c43m33))1.(cid:4))53)kd/k2
s Article. P This articl oafh0tt.1p5://amtc0mT.olererd).s.ac.uk0/.M11CM/.bAt 700–760 TorRric(kloawrdpertesasl.u3r9e limit fooblslOoewnrveiendpgofstoeerncttCiioaHln3seC.xHplOanOataionndf(oCrHt3h)e2CoObOseravreedpcruersveantuterde iinn tthhee
s
e
Acc CH3CHOO and (CH3)2COO data is measurement error. DSO2 is
en Fig.1showsthecumulativeconsumptionofSO2relativeto relatively small at high [H2O] compared to the precision of the
Op that of O3, DSO2 versus DO3 (after correction for dilution), as a measurements;however,evenallowingforassociateduncertainties,
function of [H O] for each experiment for the four alkenes thepointsathighRHdonotfitthelinearrelationshipsuccessfully
2
studied.Afittoeachexperiment,extrapolatingtheexperimental appliedtotheremainingdatapoints.Moreover,anysystematicerror
datatoevaluatedSO /dO att=0(startofeachexperimentalrun) inthemeasurementofO,SO orHOwouldalsobeexpectedto
2 3 3 2 2
for use in eqn (E1)–(E3), is also shown. The overall change in affecttheresultsfortheethenesystem(andtoagreaterextent,given
SO , DSO , is seen to decrease substantially with increasing the slow ethene–ozone reaction rate and consequent lower overall
2 2
humidity (over a relatively narrow range of RH (1.5–20%)) for chemical SO loss observed), suggesting that the cause lies in
2
allfour alkenes.Thistrendwouldbeexpectedfromtheunder- contrasting chemical behaviour. In terms of experimental factors,
stoodchemistry((R1)–(R4)),asthereiscompetitionbetweenSO , HO was measured using multiple approaches (two dew-point
2 2
H O,anddecompositionforreactionwiththeSCI. hygrometers in addition to a solid state probe) with no evidence
2
Fig. 3 shows a fit of eqn (E3) to the data for each alkene, for any divergence with RH. SO monitors can exhibit humidity-
2
givingaslopeofk /k ,andaninterceptof(k +L)/k .Theresults dependentinterferences(quenchingoftheSO signal),commonlyof
3 2 d 2 2
appear to show a generally linear relationship; however, for cis- theorderofafewpercent,observedatveryhighRH,andcorrected
andtrans-but-2-eneandTME,thedatapointatthehighestrelative through incorporation of a nafion dryer (fitted in this case); in
humidity accessible in this work ([H O] = 1.5–2.0 (cid:3) 1017 cm(cid:4)3) additionthemonitor-derivedSO concentrationincrementswerein
2 2
appearstodeviatefromthisrelationship.Thesedatapointslie agreement with those calculated from the measured SO addition
2
outside the 95% confidence intervals defined by all the other andchambervolume,acrosstherelativehumidityrangestudied.
(lowerrelativehumidity)dataforeachalkene.Fortheanalysisto Itshouldbenotedthatthek valuesreportedhererepresent
d
determinek /k and(k +L)/k presentedinTable2,thepointsat upperlimits,asaconsequenceofpossiblefurtherchemicallosses
3 2 d 2
the highest RH are excluded and the kinetic parameters are forthe SCI within ourexperimental system(as represented by
derived from a linear fit to the measurements from all other Lineqn(E3),notwithstandingtheapproachofextrapolatingto
experiments.Extendedanalysestoaccountforthenon-linearity thestartofeachexperimenttominimisethese).Otherpotential
4080 | Phys.Chem.Chem.Phys.,2015,17,4076--4088 Thisjournalis©theOwnerSocieties2015
View Article Online
Paper PCCP
fates for SCIs include reaction with ozone,42,43 other SCI,43 (a fast reaction of CH OO with (H O) would be manifested
2 2 2
carbonylproducts,44acids,45orwiththeparentalkene43itself. asasignificantupwardcurvatureinFig.3).However,thisdoes
Sensitivityanalysesindicatethatthereactionwithozonecould not mean the results are inconsistent withreaction of CH OO
2
besignificant,aspredictedbytheory42,43withapossiblecontribu- with(H O) .
2 2
tionofupto10%ofSCIlossfor(CH)COOat2%RH,whiletotal InFig.4,eqn(E4)(anexpandedversionofeqn(E3),including
32
lossesfromreactionwithSCI(self-reaction),carbonylsandalkenes the SCI + (H O) reaction (R5)) is applied to the data, now
2 2
arecalculatedtoaccountforo1%ofthetotalSCIlossunderthe expressed in terms of (H O) , calculated for each RH via the
2 2
experimentalconditionsapplied. equilibriumconstant.48
20. d Licence. 3.23.2C.1H2OLOinearFit.ForCH2OOalinearfit(i.e.usingeqn(E3) ½SO2(cid:5)0(cid:3)1f (cid:4)1(cid:4)¼kk32sffi(cid:6)ffiðffiffiHffiffiffiKffi2ffiffiOffipffiffiffiÞffiffi2ffiffi(cid:7)ffiffiþkk52(cid:6)ðH2OÞ2(cid:7)þkkd2 (E4)
12:37:nporte [vHs.2HO]2Ora)ndgeescsrtiubdeisedth(e1–o2b0se(cid:3)rv1a0ti1o6nmsowleelclu(lFeisg.p3er)ocmve(cid:4)r3t)h.eThenistifriet Thevaluefork3/k2(watermonomer)derivedfromthefitshown
8/2017 n 3.0 U g(cid:4)i2ve.3s(r(cid:2)el3a.t5i)ve(cid:3)ra1t0e1s1kc3m/k(cid:4)23o(fT3a.b3le((cid:2)21)..1)(cid:3) 10(cid:4)5and(kd+L)/k2 of iinnsFenigs.it4iveisto2.5th(e(cid:2)i0n.c7l)u(cid:3)sio1n0(cid:4)of5.thIteis(Hs2eOen)2ttheramt thinisevqanlu(eE4is)arasththeer
oaded on 15/0ons Attributio dathbireseToachltbuemstsoeeelumtrheteeloaadktsi2suvaveraterlmraueteedesnsutrccseeapdnoofpbrtkreee2pd(sSslaCbucyrIeeW+d(4eoSlnOTzo2ae)rnt.r)aIa,nlbt.o,s1To5tahlobueblteerteab3lianawtseiidveseuuarpssaiiptnnelggys 1vpaab0rles(cid:4)uso1eel6unittcseemdvwa3ilinutsheF(cid:4)iniu1g.s.itnT3hghe–ethsueedneeckera2irlfvstraeooidmnTtaivWebaslleeuloze2f.eotCthfaolen.k1vd5le/igknrit2evinaeirsgsktf3(cid:4)hit=i6st.9o4v.9al(t(u(cid:2)h(cid:2)ee62t6.od9))aat(cid:3)(cid:3)na
wnlmm shown in Table 2. Using this method, the value obtained for 1010cm(cid:4)3,which,usingtheWelzetal.15k2givesanabsolutevalue
ccess Article. Published on 06 January 2015. Do This article is licensed under a Creative Co rckawk(cid:4)(r3hreeo33.naei98pc(ntdaosCe.3hTo(cid:3)c8sn.HprhSti2tti4st(rtee.o1h2(cid:2)t2oeedO(cid:3)0neednds1(cid:4)nOtie(e3et1i1ctRChmrx1)0tei5wHepe+(cid:4)vstca)deei(cid:4)m)21atrtrOd5e1tHhelki3o,.smaOcd12(sictm7o(bkO.h(cid:4)Cetedfei(n)3e1.+oHkOv+tn3sz(reia2ru(cid:4)ese(oeOrLlyrH1oyclf)oay,O.ef12fnbv91naOd).waC3g5ustet)(cid:3)lit)Ht2ouetr)d.h(,(itie21(cid:2)ev1sbiiOa.entnR0e1f(0leOdoc.(cid:4)e.r1bs(cid:3)ua4rc1m8vmr.7ne)woaC(1n1ikccaailnH0(cid:3)4tt3uemdlha(cid:4)–lre=2tt531aeO(ai121trB0gxohsieO0.prcnn(cid:4)5tepe(cid:4)0meit1eomu(r1.yb)(cid:2)3mwi35r..smyetais1Tseensc(cid:4)tWe)(cid:4)ndhe)mgn1(cid:3)1treget)h–t3owra,ld1hezelraii0iraietnssmeshe(cid:4)tt(cid:4)swtie.a1ue1mctor7ag.rhmar,ltrcelek.hTeim,to(4wn1heaHh6r5gm3nooei2sttrsdOkhihetk(cid:4)c2hn)aa2aii12=esss2tt)l, fWzNCwfepfbboaietayutoiocrretsratntSohtTalkeolgztvwim.dhoinr1eenetie5onnhreottutfhteeeregfaiene(cid:4)nqriilternvas.clwnsgta1ueet(areoet.asrl(5ogttntldEh.aiekf31(vt4naii5(cid:2)uy7an)sug(cid:3)csrT=st1ttnyiyvtoom6hn1o,ca5ir)en0gedlaa.usr6(cid:4)oaselitet(cid:4)lnen1fthaeq(ie13sis(cid:2)erot.rnnecwamfTtot7ttmbhh(iokph.peEis0ae5n3tislo4/oi)snoekmsk)lfi(cid:3)i2tu(cid:4)dtnstwithih1t(shdnewa)i1eaekteeg(0tadhFtrvviak,(cid:4)etoeuiaa3iegkrnfn1r/lplrm.3k.ue3u;p/24i4sdeekcniceu5nia2oamddrml)unentlfiesfidl3idsssenrirxotiemoriseignfkvq)nsmr(cid:4)dg5eiohuigf/t1dsrkmetuo.totfo21nhwihboTms.tvee9eyr4hshlaqy.daBitkl9(aknsukw(cid:2)ba5el2d(cid:3)elltori(1oedassEwnf.w.aer18fp3darorddi)0)orstonmude(cid:4)(cid:3)u(megfFscii1tgtxeei61ithWgaezndoh0ad.elltn.yr(cid:4)enr3e,betao4l2dd)oaezy6l..,
A
n predictions,47butincontrasttootherexperimentalwork.45 kdfixedtozero.Onefitlineusesthek5valuereportedbyBerndt
pe et al.46 (blue dashed line). This is seen to overestimate the
O
CH2OOþðH2OÞ2 (cid:2)k!5 products (R5) presented data. The green dotted line shows a fit to the upper
limits of the uncertainties of the measured data. This yields
TheCH OOdatafromthisstudyappeartobewelldescribed a k /k value of 0.10 ((cid:2)0.01), giving an upper limit k value of
2 5 2 5
by a linear fit under the experimental conditions applied 3.9((cid:2)0.39)(cid:3)10(cid:4)12cm3s(cid:4)1.
Table3 ComparisonofSCIrelativerateconstantsderivedinthisworktorelativeandabsolutevaluesfromtheliterature.Uncertaintyranges((cid:2)2s)
indicatecombinedprecisionandsystematicmeasurementerrorcomponents
SCI 105k /k 1015k (cm3s(cid:4)1) 10(cid:4)11k /k (cm(cid:4)3) k (s(cid:4)1) Ref. Method Conditionsa
3 2 3 d 2 d
CH OO 3.3((cid:2)1.1) 1.3((cid:2)0.4)b (cid:4)2.3((cid:2)3.5) (cid:4)8.8((cid:2)13)b Thiswork Etheneozonolysis 298–303K
2
o4 Welzetal.15 Alkyliodidephotolysis 4Torr;298K
o0.09 Stoneetal.17 Alkyliodidephotolysis 200Torr;295K
CH CHOO 26((cid:2)10) 12((cid:2)4.5)c 13((cid:2)43) 59((cid:2)196)c Thiswork C2Bozonolysis 296–302K
3
33((cid:2)10) 15((cid:2)4.5)c (cid:4)14((cid:2)31) (cid:4)64((cid:2)141)c Thiswork T2Bozonolysis 297–302K
anti10((cid:2)4);syno4 Taatjesetal.16 Alkyliodidephotolysis 4Torr;298K
8.8((cid:2)0.4) 12((cid:2)0.1) Berndtetal.32 T2Bozonolysis 293K
76(25–228) Fenskeetal.26 T2Bozonolysis 296K
(CH ) COO 8.7((cid:2)2.5) 2.1((cid:2)0.6)d 63((cid:2)14) 151((cid:2)35)d Thiswork TMEozonolysis 298–299K
32
o0.4 42((cid:2)3) Berndtetal.32 TMEozonolysis 293K
aExperimentswereconductedatatmosphericpressureunlessstatedotherwise.bAssumingk =3.9(cid:3)10(cid:4)11cm3s(cid:4)1(Welzetal.15).cAssuming
2
k =4.55(cid:3)10(cid:4)11cm3s(cid:4)1.Averageofk forsynandantiCH CHOOconformersfromTaatjesetal.16dAssumingk =2.4(cid:3)10(cid:4)11cm3s(cid:4)1.k forsyn-
2 2 3 2 2
CH CHOOfromTaatjesetal.16
3
Thisjournalis©theOwnerSocieties2015 Phys.Chem.Chem.Phys.,2015,17,4076--4088 | 4081
View Article Online
PCCP Paper
by Taatjes et al.16 gives a value of 7.0 (cid:3) 10(cid:4)15 cm3 s(cid:4)1, while
Sheps et al.49 give a mean value of 12 (cid:3) 10(cid:4)15 cm3 s(cid:4)1. The
valuesobtainedfor(k +L)are59((cid:2)196)s(cid:4)1fromcis-but-2-ene
d
and(cid:4)64((cid:2)141)s(cid:4)1fromtrans-but-2-ene.Clearlythereisalarge
uncertaintyassociatedwiththek determinedfromthisanalysis.
d
Fenskeetal.26havereportedk (CH CHOO)fromtrans-but-2-ene
d 3
ozonolysistobe76s(cid:4)1(accuratetowithinafactorofthree).
3.2.2 Two conformer system. In Fig. 1 it is evident that
e. dSO2/dO3 falls rapidly with increasing [H2O] for all but-2-ene
c
n experiments as RH is initially increased, but that the experi-
e
c
20. d Li ments at higher RH all appear to display a similar dSO2/dO3,
2:37:porte lie.ev.etlsheofftr.eFnrdomintdheiscroeabssienrgvaStiOo2nrietmapovpaelarwsitthhaitncthreearseinmgaHy2bOe
08/2017 1on 3.0 Un CFSiOHg2.2.O4InOsAewtp:iptehlqicnHat2(iEOo4n)(kao3s/fks2eh)qoanwnnd(Ei(4nH)t2hOtoe)2md(eka5rini/vkef2ig)ruraerteleat(ricveeodntlsointaetnh),tas(tE4ofo)fraCprHpe2aliOecdtOiounwsiniotghf cmoamnpifeetsitnegdHin2OFidg.ep3eansdeanccuiervsintogtohveerSOof2tlhoessdpatraesaetnht.igThhiRsHis.
oaded on 15/ons Attributi t(edhtahesedhniemeddelraintreae)a(sacontildoidnagrfraietteeonf(k(l5iEn)4er)e).ptoorttheedubpypBeerrlnimdtitsetoafl.t4h5e(1u.1nc(cid:3)er1t0a(cid:4)in1t1iecsmin3st(cid:4)h1e) cbWfioerenshtfalopyvrritmoohupaeortrssimetfaaotryrwimsoreeesfdplfeoriocsntsmibtbhduleeitff-2pee-xrrepiennsleagennokaczitenoioenotnoifcslysasfnoiosfr;athdstehedciitostwinooodnbClayslHetro3hvCxaaiHttdiaOothnnOet:
nlm
wm beingformedintheozonolysissystemthatreactswithSO butis
5. Dove Co in rTehlaeticoonnttroibuthtiaotnooffH(H2O2O)a2sto[Ht2hOe]reinmcorevaasleosf.CHHen2OceOaintctryepaisceasl lesssensitivetoH2O.Thefirstofthesepossibilitiesisdis2cussed
201eati atmospheric[H2O](B2.5–7.5(cid:3)1017moleculespercm(cid:4)3),greater below,the secondisdiscussedinrelationto(CH3)2COO inthe
ublished on 06 January e is licensed under a Cr ttbjuuhhenseacdtnoaetmtrhwmeeesaotsHitsmhpa2Oechacteeemdrseotso.hminbeiolntemoatineanrtletkshfiifninesekctstitcofusofdrwiyn,aCtmrHeero2aOodctneOilo.srnewImnwooiuttvlhhadils(coHofc2nCaOssH)ied22eOcuroOsauibnillndgy cfaatcohiopnslant-plOionf-aaocwnrnoretiemdhnnnefegteotxrrrsipsanmeyrlncnaeesFtan--ircibcoasgotunt.snito.of3-wf2on-riieCtmsfhnoHteerhH3r.C,te2IhHtOwdeOhhiffosiaOelbesevsrepiebtnrrrheavgoeleednrdouerracpadnetcreoedetrnidsvc-iiilocntoitinnfeesetdsmhta5aeor0aniftgttoynhtzhfiaaootettunrdhosthtyelihygnesefh-iaasasSRnntCtoeHdirIf-
Article. PThis articl 3.33.3C.1H3CSHinOgOle SCI Approach. The CH3CHOO data shown in arebaocutitoanfwacitthorSoOf2thhraesebgereenatderetfeorrmtihneedanetxi-pceornimfoermntearllyt1h6antothbee
s Fig. 3 for both cis and trans-but-2-ene appear to be well syn-conformer. The fraction of each conformer that is lost
s
e
Acc described(withintheuncertainties)byalinearfittoeqn(E3), to reaction with SO2 can be considered in the same way as
en withtheexceptionoftheexperimentatthehighestRH([H2O]= illustratedineqn(E2),leadingtoeqn(E5)and(E6)below,plus
Op 1.8–1.9(cid:3)1017cm(cid:4)3)inbothcases.Thekineticparametersderived simplifications outlined in the following text. The total loss of
fromalinearfittothedata(Fig.3),usingeqn(E3)(whichtreatsthe SO toCH CHOOisthenthesumofthefractionallosstoeach
2 3
system as producing a single SCI), excluding the highest RH conformer,multipliedbytherelativeSCIyield(g)(i.e.jsyn/j)of
experiments,areshowninTable2.Verysimilarresultsareobtained thatconformer(eqn(E7)).
fork /k forCHCHOOderivedfrombothcis-andtrans-but-2-ene
3 2 3 ½SO (cid:5) ½SO (cid:5)
ozonolysis, with values of 26 ((cid:2)10) (cid:3) 10(cid:4)5 and 33 ((cid:2)10) (cid:3) 10(cid:4)5 fsyn¼ ksyn 2 ksyn(cid:7) 2ksyn (E5)
respectively.The(kd+L)/k2obtainedforCH3CHOOfromcis-but-2- ½SO2(cid:5)þk3syn½H2O(cid:5)þkdsyn ½SO2(cid:5)þkdsyn
eneozonolysisis13((cid:2)43)(cid:3)1011moleculecm(cid:4)3andfromtrans- 2 2 2
but-2-ene ozonolysis (cid:4)14 ((cid:2)31) (cid:3) 1011 molecule cm(cid:4)3. Berndt
½SO (cid:5) ½SO (cid:5)
etal.32reportedthek3/k2ratiofromtrans-but-2-eneozonolysis fanti ¼ kanti 2 kanti (cid:7) ka2nti (E6)
to be 8.8 ((cid:2)0.4) (cid:3) 10(cid:4)5 (also assuming a single SCI system), ½SO (cid:5)þ 3 ½H O(cid:5)þ d ½SO (cid:5)þ 3 ½H O(cid:5)
2 kanti 2 kanti 2 kanti 2
afactorof3.75smallerthanthatreportedhere. 2 2 2
The relative rate constants (Table 2) can be placed on an
absolutebasisusingthemeasurementsofk (SCI+SO )reported f=gsynfsyn+gantifanti (E7)
2 2
by Taatjes et al.16 (derived using the same methodology as
Eqn(E8)canthenbefittedtothedatapresentedinFig.3for
forCH OO)(Table3).Aseqn(E3)treatstheSCIproducedasa
2
single SCI, we use an average of the syn and anti conformer cis-andtrans-but-2-ene(Fig.5).
ratespresentedinTaatjesetal.,164.55(cid:3)10(cid:4)11cm3s(cid:4)1.Using (cid:3)1 (cid:4) (cid:3) 1 (cid:4)
½SO (cid:5) (cid:4)1 ¼½SO (cid:5) (cid:4)1 (E8)
thismethod,thevalueobtainedfork3(CH3CHOO+H2O)from 2 f 2 gsynfsynþgantifanti
cis-but-2-eneozonolysisis12((cid:2)4.5)(cid:3)10(cid:4)15cm3s(cid:4)1andfrom
trans-but-2-eneozonolysisis15((cid:2)4.5)(cid:3)10(cid:4)15cm3s(cid:4)1.Taking Here we make two assumptions to reduce the degrees of
ameanofthek valuesreportedforthetwoCHCHOOconformers freedom and hence make the problem tractable with the
3 3
4082 | Phys.Chem.Chem.Phys.,2015,17,4076--4088 Thisjournalis©theOwnerSocieties2015
View Article Online
Paper PCCP
dataset available. First it is assumed that ksyn[H O] may be
3 2
neglected,inkeepingwiththeoreticalpredictions24predicting
ksyntobeoverthreeordersofmagnitudegreaterthanksyn[H O].
d 3 2
Further theoretical work50 predicts a rate constant for syn-
CH CHOO + H O of 2.39 (cid:3) 10(cid:4)18 cm3 s(cid:4)1, and recent experi-
3 2
mentalwork49yieldsanupperlimitforksynofo2(cid:3)10(cid:4)16cm3s(cid:4)1.
3
Hence with ksyn expected to be relatively fast, given the decom-
d
position rate presented here for (CH ) COO (a syn-conformer)
32
e. andthefaciledecomposition routeavailableviathehydroper-
c
n oxidemechanismforthesyn-conformer,itcanbeassumedthat
e
c
8/2017 12:37:20. n 3.0 Unported Li mtdSkhsdeoyeecnmnocbtnianudlatk-tci2s3etoy-dneni[snHdbeai2ytsOidsot]aunhtamseateutiadhnsneettFdihe-i.caxgoptI.fnek3rftadoihnmarteisme{knreiertnpakeltra3thencistceoie[snnHnddt2tiieOhntrie]giovunekansdddsrfediernrpeogromtlihrevteeetSddreCexahfIprteeoiarnrmreige-. Fefriqagnc.t6i(oEn8T)ohfteothrtehanetogtbeausltC-o2Hf-3ekCna3HnetOi/dkOaa2ntatfior(aFmnigde.d5kt)sdh.ynaT/tkhis2seynscyodnel-oCtueHrrm3lCeingHeeOdnOdfrs(oghmsoynw).fsitttinhge
0o
oaded on 15/ons Attributi ttrrhheeppeesoouerrttnkkacia3ennvrtaetialttuiiocnesbt,ioeefws12,h.0.s4icu(h(cid:2)(g(cid:2)g0i0e.s4.s4)tis)(cid:3)n(cid:3)dth1i1s0at0(cid:4)ti(cid:4)n1k41gad4cnutmciismi3hs3as(cid:4)bssm1(cid:4)le,1aw.lfThlr.ohilmTueasSa,zhteejeevrpesosneewtatitaathtllh..i14ne69 oanftdhetriarnpsr-ebcuutr-s2o-ernaelkeexnpee,rtihmeemnetsascuarnembeenutssefdroimntchoemcbisi-nbautti-o2n-entoe
wnlmm lowest [H O] considered here (B1 (cid:3) 1016 cm(cid:4)3), loss of anti- constrainkanti,ksynandalsogsynandgantifromeachalkene.Fig.6
oo 2 3 d
ublished on 06 January 2015. De is licensed under a Creative C dCnusvhaseeHleorguF3diwlevCii.tgesttHAdihifbnsOoelkgreOtsa3hanekitnemqa3itnnoacCteino(IkaHEsmdin,8n2dpk)oOesdanttykiornccsdwiyestvnbohoafeudneolhulerdda(pemivasneitebnocabdeludyusreahd4oninointnd1w5tog0%hntn0hae)ies.tnkserhadm(cid:4)enFe1txiia,vgpola.ieafsl5rune5iedmdd0s,eserdao(cid:4)nirfev1tecesgcosaeihrnmxartapienpreasaogcpnntesedegiscdtetitgiohsvtoynoeenf cgCkcpmpisesdrlHsyyoepen-nFbttst/seakCeiurrgns2nettHsy.h-dpnt.2Oeer6-UgdteeOoaksnsdna3aeietcnebnirntoeti(egtaenT,svnrfasu1ttmod.hbh.nr2kleiesmtensdruyu(raen4e(cid:2)rensnrp)dl.i1sserqe-k.ivfb1utsa3raeu)nieonnrttimm(cid:3)s-/tg2kolia2-vylTnenu1a,nate0ltiluaidea1ott.3erjonagseWctesfmboodheaefrite(cid:4)sffbrka33ete2o.lh.r.t51etTefh6honrh(keertt(cid:2)eoa3sgante3phst2riy.el1esntaaw)ntcaswoudeny(cid:3)nondtklchisdnf1egayern0raenetnrs(cid:4)aedatein4ilipnfadnaraatttnofiinreveotmardiesr---
Article. PThis articl r((cid:2)at2e3.1c)o(cid:3)ns1ta0n(cid:4)t1s4comn3ans(cid:4)a1basnodluftoerbksdaysniosfg2iv8e8s((cid:2)a2v7a5lu)es(cid:4)fo1.rTkha3nistikoa3fnt2i.i3s
s comparable to (a factor of two greater than) that reported by
s
e
cc Taatjesetal.16(1.0((cid:2)0.4)(cid:3) 10(cid:4)14).Novellietal.23haverecently
A
en reportedksdyntobeanorderofmagnitudesmaller(3–30s(cid:4)1)based
Op on direct observation of OH formation during trans-but-2-ene
ozonolysisatatmosphericpressure.
The point of interception in Fig. 6 also determines the
relative yields of the two conformers, gsyn and ganti (which in
turnhasbeenusedtoderivetheoptimisedfitsshowninFig.5).
Forcis-but-2-enethesearedeterminedas0.45and0.55forgsyn
and ganti respectively. For trans-but-2-ene they are determined
as0.25forgsynand0.75forganti.Theanalysisperformedinthis
sectionhasimplicationsforthedeterminationoftheSCIyield.
Usingtherelativerateconstantk /k (anti-CH CHOO)obtained,
3 2 3
as shown in Table 4, it is calculated that B90% of the anti-
CH CHOO produced in the SCI yield experiments would react
3
with SO . From the determined k /k (syn-CH CHOO) it is
2 d 2 3
calculated that B67% of the syn-CH CHOO produced in the
3
SCI yield experiments would react with SO . Applying these
2
(with the corresponding syn and anti yields shown in Table 4)
correctionstoj determinestotalSCIyieldsof0.29fortrans-
min
but-2-eneand0.42forcis-but-2-ene.Thesevaluesbothliewithin
the uncertainties inthe SCI yieldspresented inTable 1 for the
twobut-2-enesystems.
Fig.5 Fits of eqn (E8) to the cis-but-2-ene and trans-but-2-ene data
showninFig.3.gsynandgantiare0.45and0.55forcis-but-2-eneand0.25 It is not practicable to assess the possible contribution of
and0.75fortrans-but-2-ene(seeFig.6). the water dimer to the SCI loss for CH CHOO because of the
3
Thisjournalis©theOwnerSocieties2015 Phys.Chem.Chem.Phys.,2015,17,4076--4088 | 4083
View Article Online
PCCP Paper
Table4 Kineticparametersderivedforsyn-CH CHOOandanti-CH CHOOfromtwo-componentfitstothetrans-but-2-ene(T2B)andcis-but-2-ene
3 3
(C2B)experiments(seeFig.5).Alsorelative(g)andabsolute(j)yieldsofthetwoconformers
ga j
CH CHOO 104k /k 1014k (cm3s(cid:4)1) 10(cid:4)13k /k (cm(cid:4)3) k (s(cid:4)1) T2B C2B T2B C2B Ref. Conditionsb
3 3 2 3 d 2 d
syn — — 1.2((cid:2)1.1) 288((cid:2)275) 0.25 0.45 0.07 0.17 Thiswork —
o0.4 Taatjesetal.16 4Torr
o0.02 Shepsetal.49 200Torr
20(3–30) Novellietal.23 735Torr
ce. anti 3.5((cid:2)3.1) 2.3((cid:2)2.1) — — 0.75 0.55 0.21 0.21 Thiswork —
en 1.0((cid:2)0.4) Taatjesetal.16 4Torr
c
20. d Li 2.4((cid:2)0.4) Shepsetal.49 200Torr
2:37:porte agsyn=jsyn/j.bExperimentswereconductedatatmosphericpressureunlessstatedotherwiseandtemperaturesfrom293to303K.
1n
7 U
2013.0 numberoffreeparametersthatwouldresultforasmalldataset. theapproximationthatthisspeciesdoesnotreactappreciably
08/on However,theoreticalpredictions47suggestthatthismaybeless withwatervapour.Ineqn(E9),fisthesumoffSCI(thefraction
oaded on 15/ons Attributi tkimh(Hapn2oOrf)otatrnoCtbHfeo2trOwOCoH.o3rdCeHrsOoOfmthaagnniftourdCeHsm2OaOlle,rinfodricaanttiin-CgHk3(CHH2OO)O2/ aoyisfesSludCmIoprfettiahocentitnoogftanwleiogtxhliigdSiaObnl2et)(Hain.2edO.SfrCxe,Iaec+aticXvh)itgymS,Cu(IdlatSinOpdl2i/egddxO.b3F)yoxltilhnoewerqiennlga(tEtihv9ee)
wnlmm canbederivedfromtheSO2lossatthehighestRHexperiments
2015. Doeative Co 3.43.4(.C1H3L)2iCnOeaOrfit.For(CH3)2COOavalueof8.7((cid:2)2.5)(cid:3)10(cid:4)5 T(oifh.eOe.rwe(hfdoeSrneO,all/oldstOsheo)fSiOSsO2a2lpofpsrrsoomixsimarettaartciebtliuyotn0e.d0w2tit5oh.XjX+,rerSepOlra2et)sioveefnBttso1tth0heeptploobtsavsl.
y Cr (Table 2) was obtained from a linear fit to the data in Fig. 3, 3 2 3x
ess Article. Published on 06 Januar This article is licensed under a vdgrck1(eCea2ax.re6(ponclHtsueoluy(cid:3)u3rernbpm)tds-e21eCiCid0ifnHnnpo1Og7elkr3aOad2CctckhmHe3svaiedyas(cid:4)sO(nl(eu3CO6oa)xeo3nHpfsr+rsei(o3ay(cid:2)ferS)monni2nOm1rC-tc42taaO()eoh)bCtnnreOis(cid:3)Hoetofrpno3+elp1ou)rg2e0rmtHtrCroet1eefH12esodObtsrmOrhia)mboes(Ooynoiie.sltfe.eTdfe.(cr2aurkouaam.tsdm1lhttie+jnitee(ngh(cid:2)pLsrdaee)eie/0tlrrkhthe.i2o6esaccix)fgtmlo.ymah1(cid:3)erg(cid:4)6lexwee(3aspC1an.atse0sH)TyrRu(cid:4).tsih3hrmH1T)eee25ahmCsre(ceeni[OmemsHtavnOsrg2ae3teOlstiawusvhnn](cid:4)eaeoydo=sss1fl cEt(oohhxqeian0dn.aa5(gdEn)e,d1tfsti0hyt¼l)iie(cid:3)ioeitnsltng1dlSjeatChl,(I(ieafo0.ensSx.(cid:4).3Cicadj1Ian–alþSc0Cneu.Igtx3lxa+pt4ftea)ejxrndfmx¼dr)fo.e.rgmoAdSmsCvstIeuhfcroSmesCrirvoIienanþclgtuoif1ntefh(cid:3)gepadqjtrdSnemOgOsxi(en3E2ina(cid:4)s3ts)exnitdnohtiaSndtecoiTntmiaco(bliEnunl9ed3a).ne11st.,
Acc andforkdof151((cid:2)35)s(cid:4)1(Table3). ½SO2(cid:5) f (cid:4)1
en Berndt et al.32 have recently reported the k3/k2 ratio for
Op (CH3)2COOtobeo0.4(cid:3)10(cid:4)5(i.e.approximatelyafactorof22 20 1(cid:4)1 3
lporwederictthioanns5t0haelsroelsautigvgeesrattke3rtoepboertveedryisnlotwhi,s3.s9tu(cid:3)dy1)0.(cid:4)T1h7ecomre3tsi(cid:4)ca1l. ¼½SO2(cid:5)664BB@½SO (cid:5)þgSCkI3½½SHO2O(cid:5)(cid:5)þkdþf1(cid:3)ddSOO32(cid:4)xCCA (cid:4)1775
Nomeasuredvalueshavebeenreportedfork ((CH ) COO),but 2 k 2 k
d 32 2 2
amorefacileoveralldecompositionthanforCH2OOorthemean (E10)
of the CH CHOO isomers might be anticipated as the vinyl-
3
hydroperoxideisomerisationchannel26isalwaysavailable. Fig. 7 shows eqn (E10) fitted to the TME data from Fig. 3.
3.4.2 Additional oxidant. In the case of the SCI formed from Itisnotpossibletodetermineuniquevaluesfortheparameters
TMEozonolysis,(CH)COO,thereisalwaysamethylgroupinasyn included in eqn (E10) due to the degrees of freedom vs. the
32
positiontothecarbonyloxidemoiety,thustheanalysispresentedin limiteddataset.ThefitshowninFig.7usesvaluesofj=0.34,
Section3.3.2fortheCHCHOOisomersdoesnotapply.Apossible gSCI = 0.88, k /k = 6.7 (cid:3) 10(cid:4)4 and k /k = 1.2 (cid:3) 1012 cm(cid:4)3.
3 3 2 d 2
alternative explanation for the observed behaviour (and possible However,Fig.7doesdemonstratethatatwo-oxidantsystem,as
contributor to the behaviour observed in the but-2-ene systems) represented by eqn (E10), is able to describe the data within
isthatthereisafurtheroxidant(X)ofSO,inadditiontotheSCI, uncertainty.
2
beingformedduringtheozonolysisreaction.Ifthisoxidantreacts Fig.7alsoincludesalinearfit(i.e.eqn(E3))tothefull(CH)COO
32
relatively slowly with HO, it could give rise to the apparent ‘two dataset (including the highest RH experiment). While it seems
2
component’ nature of the observations seen in Fig. 3. It may also unlikely that the curvature observed in the data is a result of
provideanalternativeexplanationoftheobservednatureoftheSO measurement error (as described in Section 3.1), this must be
2
loss from the but-2-ene experiments or could be occurring in considered as a possibility for (CH)COO in light of the two
32
additiontotheeffectsofdifferingconformerreactivities. conformer explanation not being applicable. The linear fit in
Eqn(E9)(below)isanexpandedversionof(E2),inwhichwe Fig.7givesak/k valueof3.8((cid:2)3.2)(cid:3) 10(cid:4)5cm3s(cid:4)1,afactorof
3 2
consider the contribution from a second SO oxidant, making twosmallerthanthek/k valuepresentedinTable2.
2 3 2
4084 | Phys.Chem.Chem.Phys.,2015,17,4076--4088 Thisjournalis©theOwnerSocieties2015
View Article Online
Paper PCCP
for sulphur compounds.53 Additional oxidation of SO by the
2
dioxirane, over and above that arising directly from reaction
withtheSCI,couldthenexplaintheobservedbehaviourofSO
2
intheTMEexperiments(andcontributetothebehaviourobserved
forthebut-2-enesystems).ForthesmallCICHOO,formedinthe
2
ethenesystem,ithasbeenpredictedthatthedioxiraneformedis
considerably less stable than the methyl substituted dioxiranes
formedfrombut-2-eneandTMEozonolysis,andfurthermorewill
e. decomposepromptlyduetochemicalactivation.
c
n Thepossibilityofnon-CIproductsoftheozonolysissystem
e
c
20. d Li Fig.7 DataforTMEozonolysis(asshowninFig.3),withfittoeqn(E10), being responsible for some of the observed SO2 oxidation has
2:37:porte andlinearfittothefulldataset. bexepelnansautigognesftoedr tphreevoibousesrlvyedasbaehnavailoteurrnaotfivSeO(orinatdhdeitiaotmnaol)-
1n 2
8/2017 n 3.0 U The most obvious candidate for an additional oxidant pre- tshpehierrde.a1t,5a4,w55erIne nthoetirpelarfbeocrtalytodreyssctruibdeydBberynadtmeotdael.l19innwotheicthhaat
0o
oaded on 15/ons Attributi twcshehanrasotmuatdgbohdecre,otdhnpiesnruiamemlxkaecereniSsleOsy2a+(tiinosthzOoetnHhbee.egOraienHbansceirtnianodgcnieoc.1fa1olesfHacaoshruweneepxlvipregoerhdrticumycaceelndnodhtietnNoxatOanhcxeet) sctinhionamfgtalmcettheb(enSestCeemIddoraterhtelaaa1ctt9eotdmah)repeSlSeOcOxo2.n2Tosoaxixsaidittdejaenatsittoieowntniatplih.rn5o6acoheztaswosvnoeow-crleaoycssmiesanpstsoslynyusesmtenumetgdgos,exmsaitdneaaddy-
nlm
wm as an OH scavenger, such that SO reaction with OH was tion system, either two processes removing SO in parallel (as
oo 2 2
5. Dve C calculated to be r1% of the total chemical SO2 removal in describedabove),orthroughasequentialtwo-stepSO2removal
201eati all experiments. Other potential candidates for this oxidant mechanism, such as the secondary ozonide route outlined
y Cr speciesincludethe(stabilised)vinylhydroperoxide(VHP)inter- above. However, this latter mechanism cannot (in isolation)
ublished on 06 Januare is licensed under a cmfmsetyawceilbDldlihiicirslauioeastnzceaddod,tdniroeauedtncdssta()Telwd,.co1eaio0rtrnnhrih,dvdewaradedvirsietyofhprpxeooaircrmzetlaoisnftneteoehnitdietd(meeSe(dcCec(hoHfeoeomvf3mri)mdtp2heCeoeens1Odico)tO.eritodhCfneorIror)tuooasfgutfhabopsrfreametawnsnsOuhtSiruHaOenl,2sd–VpoSrHrfeCodPaI- atgrmiecaoaacsnTcyoestshuscenfiosontplnrofrtotwetrhrhsilebeyetunhawtcerteoiemtolheobotofssHoepafr2htnvOhaeaearltktedihoe.daenndIintsfediopiatotnhnrizoeaiossnlo,neaxoonpilxdlteiyedar(sdhnnaisaonthpntieisns-rwOeiboH.nouex)ilaindddSgadhOtiifatooivnoremonxiomeitfddopatlrSttiiahCcocaaInet-,
Article. PThis articl vTihdiisngwsocuolpdebfoercboinmsoislteecnutlawrirtehactthioenksionfettihcisosbpseecriveastitoonoscpcurer-. othbisseprvoesdsiibnilirteyceisntnefieedldede.xperiments.1Furtherinve2stigationof
s sentedhere:asmallyieldinthesystemswithsyn-SCIs,whilefor AsforCH CHOO,theanalysisperformedinthissectionhas
s 3
e
Acc ethene, no VHP intermediate is available, and the standard implications for the determination of the SCI ((CH3)2COO)
en chemistry ((R1)–(R4)) can be usedto satisfactorilyreproduce the yield. Using the value of kd derived from the linear fit to all
Op observations.However,nosignificantSO2reactivityisknownfor the data shown in Fig. 7 would indicate an SCI yield of 0.33.
theperoxideoralkenefunctionalitiespresentintheclosedshell Usingthevalueofk derivedfromthe‘additionaloxidantfitin
d
VHPinisolation,henceitmaybesurprisingifthisspeciesreacted Fig.7,andtakingintoaccountthatB10ppboftheSO lossin
2
rapidlywithSO ,althoughtheoreticalstudieshavesuggestedthat thehighSO experimentwouldbeattributedtoreactionwiththe
2 2
theVHPmayreactwithH O.23 additional oxidant rather than the SCI, determines a slightly
2
Secondary ozonide species, formed as an adduct from the lowerj of0.23,andacorrectedyieldof0.32,verysimilarto
min
SCI+SO reaction,havebeensuggestedtoaccountfortheobserved that shown in Table 1. Both of these possible alternative SCI
2
isotopicexchangeinalkene–ozone–SO systems,25andaresuggested yields lie within the uncertainties in the SCI yield from TME
2
tohavelifetimesofsecondsorlonger.19Suchasecondaryozonide ozonolysispresentedinTable1.
could react with a further SO molecule (i.e. a two-component AsforCH CHOO,itisnotpossibletoquantitativelyconsider
2 3
secondaryozonidecatalysedoxidationrouteforSO toSO conver- the contribution of the water dimer to the SCI loss given the
2 3
sion), however a substantial humidity dependence to the overall limited data, but theory53 predicts k(H O) /k(H O) to be three
2 2 2
processmaystillbeanticipated(onthebasisofSCIremovalthrough orders of magnitude smaller than that for CH OO suggesting
2
theSCI+HOreaction),whichisnotobservedhere. that reaction with the water dimer would be unimportant for
2
The ‘hot acid/ester channel’ (rearrangement and decompo- (CH ) COOattypicalatmosphericboundarylayer[H O].
32 2
sitionviaadioxiraneintermediate)isthedominantisomerisa-
tion route available for anti-SCIs. Although the hydroperoxide
channel is the principal isomerisation route for syn-SCIs, the 4. Atmospheric implications
estermechanismisalsoavailable,25anditislikelythatasmall
proportionofthesyn-CIwillisomerisethroughthischannelto The derived values for k reported in Table 3 correspond to loss
3
form a dioxirane. Dioxiranes are known to be highly reactive ratesforreactionofSCIwithHOintheatmosphereof650s(cid:4)1for
2
andselectiveoxidisingagents,51,52andhaveaparticularaffinity CHOO,B3500s(cid:4)1forCHCHOOandB1050s(cid:4)1for(CH)COO
2 3 32
Thisjournalis©theOwnerSocieties2015 Phys.Chem.Chem.Phys.,2015,17,4076--4088 | 4085