研 究 論 文 JHlIllMltlHlHlLIHlltlt Ni trationmechanismofauwlbenzeneswithN O2 by K 批uoFURUKAWA暮,FujirokuYOSHIZAWA●.Yosh iakiAm U' MitsumARAI●andMaSamitSuTAMU RA ● tnordertoclarifythemechanlsrnforthearomaticnitrationwithNot,Wehve 00rriedoutthenltratlonofalkylben Zene SWithNOBandhavelnvis也gatedtherela - tionshiptxtweenthepar由Iratefactorsandtheelectrondensitiesatthesubs titu- tionpositions,therelationshipbetweenthereladveratesinthecompetitivenltra- tionsofalkylbenzenesandthelonIヱatlonpotentlalsofthesubstrat es,andthesub･ strateselecdvityinthecompetitivenitrationofmesitylene/naphthlene byGalli's method.Asar esul t.thereac也onshouldbeanelecb'Ophillcsubstitudoninvolvinga radicalca也onformedfromtheone･electrontransferprocess,whichshouldbethe rate･determiningstep. 1.Introducb'on reacdonmechanisminvolvingNO2'asanim- SincedieselexhaustgasiskJIOWntOContain portant a tta c Jdn gSpeci e shasbeensu8 8 eSted. nitrogenoxides(NOx)andpolyaromatichydro･ NIt ro･PAHsareconsideredtobeformedfrom Carbons(PAHs) , thepJ･Oductionornitro ･ thereactioninvolvingSeveralnitrogen o xides pol押rOmadchydro c arbons(ni tr o-P AHs)h the (NO 24) ,N 20 55･6) ,HNO 37) ,etc･)inthea tmo - exIlauStga s and/or in theatmospheremayOCI sphere･ Al thoughNO 2 isconsideredasoneoE cu r )-3) ･ Thenit r o-PAHscanpossiblybeharTn･ themostimportzLntattacking sp ec iest owdPAN hlto li vhgorganismduetotheirmut a 8 enicami in thea tmosphere,Onlyafewstu dies havebeen C町 Cinogenlcproperd es4I. T herefore,horder doneconcemingthemechanismforaroma也c tore tardtheformadonofni o-P AH s,itlsnec- tr nitratlontJSingNOz･ essa rytodari fy themechanismfordlearOImdc Rad.ner B) hasreportedthatthenitrationof nitra 6onof PA H wit hNO x･ PAHswithNOBinanonpolarsoLventquan tita･ Ontheo therhand , aroma也c ni tradonwithni l livelyyieldsmononitroIPAlisandther e action tricacidiswell･knowntobeofind 山 地 Iimpor- show edhlghposldonalse lecd vity.PryoretaL 9I tanceasaunitprocessforthesy nth esesof e9L- andSasakiet a l.)Q･117haveattemptedtoclarify plosiv es ,intermediatesofdy es ,medicinesand th emechanismforthearomadcn ltradonwith agricultuJ･alchemicals.Manystudiesonthis NOZintheliquidphas e･sugBeStlngthataone･ reactionhavebeencarriedoutnotonlyinthe electrontransferprocessshouldplay ani mpor- 氏eldsofindus tr ia lchemi str ybutalsointhefield tantroleinthearomaticnitratlon.However. ofphysicalorganicc_hemi stry.Asaresul t, the thedetailedmechanismisstillnotclear. ReceivedonMay 19,199 8 Therefore.wehvestudiedthenitrationof ●DepartmentofChemicalSystemEngineer･ ing,SchoolofEngineering.TheUniversity a叫lbenzieneSwithN O2 inanonpolarsolvent ofToky0 tocladFythemechrLlSmfortheaTOm細 Cmi tra一 713-1 ,Hongp ,臥m kyか ku. T okyo I131 8656, 也oh d thNO之andto Fu rtherob tai nsomeideas Japan T EL +8 1-3-3812-21I1(ext.72 93) Forretarding th eformadonoEnit ro･P A Hsinthe RI X 十81-3 -5 684-3299 atJnOSPhere. -)60- 火薬学会港 2.E xpen.m e ntal substratesandtheheatsofformationFortheir 2.1Maten'als o-complexeswithNO2andNO2'bythePM3 Benzene,toluene . o･,.m ･andp-xylen es ,mesi- method,semトempiricalmolecularorbital tylene,ethylbenZ:ene.CumeneandnaphthaLene methodMOPACver･6 L3 ),andcomparedthem wereusedasthearomaticsubstratesand withtherelativerates. dichloromethaneasthesolven t. 4.Resultsanddiscussion Thearomadcsubstrates,theirn itroderivadves 4.1N itr ationofalkyrb e nzene anddichloromethanewerepurchasedFrom 4.1.1 Pr oducts WakoPureChemicalIndustries,ud.,Tokyo DuringthenitrationofsubstrateswithNO2, ChemicalIndus tryCo.. ud. ,KantoK a8 aku Co二. therin8･nitratedproductsweremainlypro･ Inc.andFlukaasthehighest coTnmerCialgrade duced.AIdehydesandketonesproducedfrom chemicalsavailableandwereused wi Lhoutf ur一 theoxidationoftheside-Chainsofthesubstrates therpur iJi cadon.2-Ni tmmesitylenewassynth e- werealsodetected.i.i,ben祖IdehydeFromtolu- sizedbyBla tt' smethod lZ J･N zO IWaspurchased ene,tolualdehydefromxylene.andacetophe･ fromTakachiho K agak uK ogyo C0. ,I.td.. nonefromethylbenzeneandcumene.Aswe 2.2Expen'm en talMethod areintereste di JIOnlythering･nitratlon w 仙 NO Z. AcertainamountoFsubstrateandN 20 1and nofurtherIdentlrICationoftheoxidationprod･ I5mlofdichlorornethanewereintroducedinto uctswasdone.Eachisomerdistributionofthe atbee･necked100mlhskequipped wit hacon･ nng･nitratedproductswassimilartothatforthe denser.memixttJreWasStirredforabout5 nitration wi dlHN O, / H2S Ollll･ ho ur s.T TIereaCdontemperaturewasm a in tained Weobtain ed thepseudo 一氏rst-orderratecon- at15℃. s tantsfortheFormationofring･nitratedprod- Thealkylbenzene (I.0×10 12 -2.3×1 0ー2 mo l) uctsinthecompetitivenitrationoFsubstrates and1.6× 10~ Imolof.N 20 -(3.2×10- 2 molofN 20. aocordh81oEq.I inordertocalculatetheirrela･ formesitylene)Wereusedforthenit ra tionof liverateconstants (K) andthepartialratefac- eachsu bs trate.Forthe com pe舶 veni tra tionor tors(f/f o). alkylbenZene S,7･2×10 ･3 - Llxl0 -2 molor 3 alk ylbenzene(eDECeptformesitylene),9.4XI0- ･n 盲宝 =kt (I) moloftolueneandl･6 ×1011molorN 20 4Were a:initialconcentrationofsubstrate used.Forthecompetitivenitrationofmesity- x:concentJ.ationofring-nitratedproducts 1ene/p･xylene,I.0×10 -2 molofmesitylene, k:rateconstant L1×10- 2 molofp･xyleneand3･2x10-2molofN 204 t:time wereused.Forthecompetitive nit rationofmesi･ tylene/naphthalene,1.4×10-2molofeachsu b- Therelativerateconstants,thepartialratefhc･ Strateandl･6x10-2molorN201WereuSed･ torsandthelsomerd istributionsareshownin Substratesandtheirreactionproductswere Table I. directly ex tractedfromthereac也onmixtureat TYIenlb.adonrat e softhealkylben之eneS With differentdmesandanalyzedusingagasC hro- NOZaremuchsmallerthanthosewith H N03/ mato8raph(Shima血uCo l Iid.,G C づA)witha ⅠちSO .HI,e.g qthepseud o-hTSt l0rderrateconstant れameioni姐tiondetector (FID)andbygasChro- forthatofben之eneis2.9×10L 6 5'l.sincethe matograPhy一maSSspectromeby(Shimad乱 IGC- concentradonofNOBisapproximatelyesdmated 14A,GCMS-Q P 1lOOEX)usingastainlesssteel tobe0.02 IS) to o.06MJ6),thesecond･orderrate column(3mrn¢×3mSuiconeOV-lot5%Unipo rt constantforbenzenewouldbe4.8-15×10 ~与 H P60/8 0. GLScienc eshc.). MIIs-I. 3. Calcu Jationm ethod 4.1.2 Effect sofalk y ls ubsdtu en tsonaromatI.c WeCalcu latedtheel ectr onden sid esatthes ub- nitra tionr ates sdtudon･psi也on s, thetonJZadonpten d alsofthe Therelativerateconstantsforthe ni trationof Kayak uG akkaishi.Vol.59.N o.4. 1998 -Je J- TabtelReladverateconstants.pa rthlratebctorsandisomerdistrlbudons in the nltradonoFalkylbenZens wit hN O2 mol私 trate ReladverateProductPardaJratefacto homerdistrlbudon/ Subs constantK r′㌔ r 1 I-n 触 work ro 3.9×10 52 oluen 2.5×10 O-nit m-nitreitTO 1.8 1 -3 I.7x IO2 p-nitre3-nitro I.8×6.8×10 10 2 45 4-nitro 3.3Xl OZ 356 1.3×10 2 5 9.2×10 2 2.nitro 5 4-nltro5- 2.6xI O3 95 o ･Xyle∩emrxylenep･Ⅹylen ee 2.6XI iI Z 2-n ni tro 0 0 3.6× 10 3 2-nitTOiけo 7.2×l 3.9×10 2 - 3.2×10 m-ni0 -nilrotre 5.5×10O 57} - p-ni 2.3 2 -nitTO 2.1x10 29 2.4×10 m-nitro0 tre 3 7.9×10 41 benzenet p- ni tro 9.6×10 .0 674 ethylbenzeneCumene'Ni mesitylene tra benzene,toluene.xylen lon wit h H NO ,/ 叫SO.1.A) crease inth efoIIowin8Or esandmesitylenede- Xylene>p･Xylene> o ･Xylen der:mesitylene>m･ gene.Itispostulatedthat e>toluene>ben･ onthearoma也CringshotJ theelectrondensity anincRaSe in thenumberof ldbecomehigher with S也tutedonthearomadcri ng.r methylgroupssu b 一 cr e as edel ec trophiucnitradon. eTsul血 ginan in一 言 constaJltSfわrthenitration herelativerate ethylben2:eneandcumenea ofben2iene,tOluene . decreasingorder:ethylben2 reinthefouowlng ene>benZ:ene.Ttlsalso :ene≧Cumene,tOlu･ largeralkylgroupshoul postulatedthatthe densityonthearOmadc dinc托aSetheelectron notingelectrophlllc rin8,re Su l血ginpro･ degreeOftheincreasewas nltration･However,the notas fortheintroductionoFrnuldpleme hlghastht ents.Inordertoquan tlta也 vely thyIsubs ti tu- ente ffec tsofalkylgroup esdmatethesubs dtu･ tocomparetheprdalratefact s,wehaveattempted ors d th theel tro ec- tionpotentialsbecausetherelativeratesofthe one-electrontransfershouldbedependenton theenergyleveloftheHOMO(ofthesubsbT ateS) OmesityTene -LUMO(o rNO z) 8ap･Asaresult,therela也ve rateswerefoundtobedependentontheioniza一 ?rTIl･xyzene 也onpotentiaLs(Fig.2).Astheioni2adonpoten - BIene P･ tialissmaller,namely.oneelectronI'se耶ilyr e- 5 5 0 o･xyZene leasedfromthesubstrate . thenitrationrate be･ ethyJberlZene comeslarger･Kowertetal.L97studiedthehom o- b o cumene toluene geneouselectronb･ansferreactionbetweenaro - maticmoleculesandtheirradical仁ationsand indicatedthattheenergyrequiredtoremove oneelectronfromtheparentmoleculeshould 9.19.29.39.49.59.69.79.8 playakeyroJehdetermhingtheelectron tr ans･ ferrate.Kochietal.2D)studiedthearomadcni･ Ionizationpotential/eV trationwithN･nitJ'OPyridiniumcationsand Fig. 2 Relationshipbetweenlogarithmorrate showe d that.thenitrationrateshould bec orre l constantsinthe compeddv e n紬 adonsand latedwiththeHOMO･LUMO gapinthe ioniZadonpote n 血lsorsubs trates 【ArH,XPyNO 2'] complex,suggesting･thatthe mechanismshouldincludeastepwiseprocess thtp o siio n, indicatingt h atthepartialr a tefac ･ t inwhichthesubstJ'ateisselectivelycontrolled torshouldbealmostdependentontJleelectron bythechargetransferprocess.Therefore.the densityatthesiteoE n itro-substitution.Previ- resultshouldsuggestthereac也oninvolvinga ously,SasakietaLshowedfromastudyofthe one-electronreleasefromthesubstrate. subsdt u enteJrectsonthearomadcnitJ･a也on with Fu rthermore･itisreportedthat NO 2Should NO Z thatthearomadc ni tradon wit hNO Zi nCCII react wi ththereducingagentsViatheelecけon should beelectrophilicbasedonanegative transfer ZI) .anditisalsosuggeste dthat theSOMO Hamme tL 'spvalue (-I.7) lI ),andhere.wecan energeylevel 22)of NO 2ト9･75eV)shouldbelow againsuggestthat仙ereactionshouldbeap-