Ngokwemveli, i-catalyst isebenza ngonxibelelwano oluthe ngqo neereactants.Kwinkqubo entsha ye-nocontact catalytic system (NCCS), i-intermediate eveliswe yi-catalytic reaction enye isebenza njengomlamli ukwenza ukuba ukusabela okuzimeleyo kuqhubeke.Umzekelo lukhetho lwe-oxidation ye-ethylbenzene, enokuthi yenzeke xa kukho i-Au nanoclusters okanye i-cyclooctene e-solubilized, kodwa iqhube ngokulula xa zombini bezikho ngaxeshanye.I-Au-initiated epoxidation ekhethiweyo ye-cyclooctene eyenziwe yi-cyclooctenyl peroxy kunye ne-oxy radicals esebenze njengabalamli ukuqalisa i-ethylbenzene oxidation.Le nkqubo idityanisiweyo yandisa ngempumelelo isiphumo se-Au.Indlela yokusabela yaxhaswa yi-reaction kinetics kunye ne-spin trap experiments.I-NCCS yenza ukusabela okuhambelanayo kuqhubeke ngaphandle kwemiqobo yobudlelwane be-stoichiometric, enikezela ngeedigri ezintsha zenkululeko kwiinkqubo ze-industrial hydrocarbon co-oxidation.

Ngokwesiko, i-catalyst inxibelelana ngokuthe ngqo ne-reactants (i-reaction A) ukwenza uhlengahlengiso lwebhondi emiselwe yi-reaction.Ngokomzekelo, kwi-cobalt-catalyzed oxidation ye-alkylaromatics (1) okanye i-Au-catalyzed epoxidation ye-cyclooctene (2), i-catalyst iququzelela ukuchithwa kwe-athomu ye-hydrogen kwi-hydrocarbon ukuqalisa ukusabela.Kwi-free radical reaction reaction, i-catalyst ithatha inxaxheba kwi-catalytic homolytic cleavage ye-bond ebuthathaka kubaqalisi eyongeziweyo ngenjongo okanye ekhoyo njengokungcola okubonakalayo kumxube wokusabela (1, 3, 4).Amanye amanyathelo kwi-catalytic tandem reaction asenokungafuni uqhagamshelwano oluthe ngqo lwe-substrate-catalyst xa uguqulo lwe-substrate luvulwa ngemveliso eveliswe ngendlela eyiyo kumanyathelo angaphambili (5–8).Nangona kunjalo, ezi mpendulo zinyanzelwa bubudlelwane be-stoichiometric phakathi kwamanyathelo.Ngokomzekelo, kwi-Mukaiyama (ep) i-oxidation ye-alkene, i-catalyst iguqula i-reductant yombingelelo ekuphenduleni i-A, njenge-isobutyraldehyde, kunye ne-concomitant stoichiometric formation ye-epoxide (i-reaction B) (9, 10).Nangona kunokwenzeka ngokomgaqo, asazi ngomzekelo apho umsebenzi we-catalyst kukuvelisa i-S ephakathi kwi-reagent A, apho i-S isebenza njengomlamli ukuba aqalise okanye enze enye impendulo B endaweni yokuthatha inxaxheba njenge-reagent ye-stoichiometric. , ngelixa i-catalyst ingasebenzi kwi-reaction B (Umfanekiso 1).Kwiskimu esinjalo, impembelelo ye-catalyst yongezwa ngaphaya kwe-catalyzing reaction A ukuya kwi-reaction reaction B kodwa ngaphandle koqhagamshelwano oluthe ngqo neereactants zayo.Inkqubo enjalo siyibiza ngokuba yi-noncontact catalytic system (NCCS).Kwi-NCCS, ubungakanani bokusabela kweempendulo A kunye no-B azibophelwanga naluphi na ubudlelwane be-stoichiometric phakathi kwabo.Oku kuchasene neempendulo ze-tandem.Kwishishini, ubudlelwane obunjalo be-stoichiometric buhlala bubeka imiqobo yezoqoqosho kwinkqubo yokuvelisa imichiza.Umzekelo owaziwa kakhulu yimveliso ye-stoichiometric ye-phenol kunye ne-acetone nge-oxidation ye-benzene nge-cumene hydroperoxide ephakathi kwinkqubo ye-cumene (11).

I-catalyst (Ikati) ivuselela i-reaction A (AR ➔ S ➔AP) apho i-S ephakathi isebenza ngokuqalisa okanye i-catalyzing reaction B (BR ➔ BP), nangona i-reaction B ingenziwanga yi-catalyst.

Sifumene i-NCCS xa sijonga iimpawu ze-catalytic ye-solubilized Aun Clusters (apho i-n ubukhulu becala ibizi-athom ezintandathu ukuya kwezisibhozo) ze-oxidation engaphelelanga ye-ethylbenzene (EB).Siye sabonisa ukuba ezi zi-Aun ze-solubilized zenze ukuqaliswa kwe-epoxidation ekhethiweyo ye-cyclooctene (cC8═) kunye ne-O2 kunye ne-~80% yokukhetha (2).La maqela ayenziwe kwi-situ ngexesha le-Au/SiO2-catalyzed cC8═ epoxidation, kwaye bagcina amandla abo okuvelisa i-radical initiator cyclooctene hydroperoxy radical (cC8═OO·) kuyo yonke impendulo.Amaqela e-Aun anyibilikisiweyo angaqokelelwa kumxube wokusabela emva kokususwa kwe-Au/SiO2, kwaye ubungakanani bawo obuyi-avareji bugqitywe kusetyenziswa i-electron microscopy e-aberration-corrected kunye ne-fluorescence spectroscopy (2).Ukongeza kwii-Aun Clusters, le mixube yayiqulethe i-cyclooctene hydroperoxide (cC8═OOH) kunye neemveliso ze-oxidation cyclooctene epoxide, cyclooctenol, kunye ne-cyclooctenone.I-cC8═OOH yayiyifom ezinzileyo ye-hydrogenated ye-cC8═OO· kwaye ikhoyo kugxininiso lwe-0.2 ukuya kwi-0.5 M emva kwe-40 ukuya kwi-100% cC8═ ukuguqulwa.Lo mxube ubizwa ngokuba yi-Au + cC8═OOH-x, apho i-x yipesenti ye-cC8═ yokuguqulwa.Nangona kwizinga eliphantsi kakhulu kunye nexesha elide (> iiyure ze-5) zokungeniswa, i-cC8═ i-epoxidation inokuthi yenzeke nge-auto-oxidation ngaphandle kwamaqoqo e-Aun.Imixube efunyenwe nge-auto-oxidation ngaphandle kwe-Au ibizwa ngokuba yi-cC8═OOH-x.Kwi-NCCS, i-Aun e-solubilized iya kuba yi-catalyst, i-epoxidation ye-cC8═ iya kuba yi-reaction A, kunye ne-cC8═OO· iya kuba ngu-S.

I-auto-oxidation ye-EB ayenzeki lula.Kwi-145°C, kuphela yi-9% yokusabela eyenzekayo kwi-EB ecocekileyo phantsi kwe-2.76 MPa O2 (12).Phantsi kweemeko zethu ezibuthathaka kakhulu ze-100 ° C kunye ne-O2 ebhubhuzayo kwi-0.1 MPa, akuzange kubekho ukuphendula okubonakalayo kwe-EB ecocekileyo ubuncinane iiyure ezingama-20.Ukongezwa komqalisi wasimahla bekufuneka ukuze le ntshukumo iqhubeke.Ukuqaliswa nge-2,2′-azobisisobutyronitrile (AIBN), i-radical radical initiator esebenzayo kakhulu, ibangele i-auto-oxidation ye-EB kunye ne-avareji yobude bechain ye ~3 (fig. S2A).Itsheyini emfutshane (~1) yabonwa kusetyenziswa i-tert-butyl hydroperoxide (fig. S2B), kwaye bekukho ukusabela okuncinci okubonakalayo kusetyenziswa i-cumene hydroperoxide encinci esebenzayo.Ke, i-auto-oxidation ye-EB yayinempembelelo encinci kwiziphumo zokusabela ezichazwe ngezantsi.

I-oxidation ye-aerobic ezinzileyo ye-EB ukuya kwi-EB hydroperoxide, i-acetophenone, kunye ne-phenylethanol ifunyenwe ngokungeza i-Au + cC8═OOH-50 equlethe umxube we-Aun, cC8═OOH, kunye ne-cC8═ engaphendulwanga (Umfanekiso 2, i-curve 1).Njengoko kuboniswe ngolu vavanyo lulandelayo, la macandelo mathathu adlale indima ephambili kwi-oxidation ye-EB, kwaye ahambelana ne-catalyst, i-S, kunye ne-AR kwinkqubo ye-NCCS eboniswe kwi-Fig.

(i) 7 ml ye-EB + 3 ml ye-Au + cC8═OOH-50;(ii) 7 ml ye-EB + 3 ml ye-Au + cC8═OOH-50 + 1.2 mmol Ph3;(iii) 7 ml ye-EB + 3 ml ye-Au + cC8═OOH-99 + 0.6 mmol Ph3;(iv) 7 ml ye-EB + 3 ml ye-cC8═OOH-50;(v) 7 ml ye-EB + 3 ml ye-cC8═OOH-50 + 1.5 mmol Ph3.Ubuninzi be-PPh3 eyongeziweyo yamiselwa ukuba ilingane nobuninzi be-titrated hydroperoxide (iqondo lokushisa lokuphendula, i-100 ° C).

Phantsi kweemeko zethu, akukho oxidation ye-aerobic EB ibonwayo eyenzekayo kumxube we-cC8═ kunye ne-EB (okt, ngaphandle kweKati okanye i-S).I-Triphenylphosphine (PPh3) iyasebenza kakhulu ekususeni i-hydroperoxides.Isisombululo se-Au + cC8═OOH-99, esicinyiweyo se-cC8═OOH ngePPh3 yokudibanisa, equlethe i-Aun kunye ne-cC8═ encinci kakhulu engaphendulwanga, ayiphumelelanga ukuqalisa i-EB reaction nasemva kweeyure ze-2 (Fig. 2, curve 3), ebonisa ukuba uAun iyodwa yayingasebenzi.Esi siphumo sabonisa ukuba ezinye iimveliso ze-cC8═ oxidation, ezifana ne-cyclooctene epoxide, i-cyclooctene alcohol, okanye i-ketone, ayikwazanga ukuqalisa i-EB oxidation.Ngokuchasene nolu vavanyo lungentla, ukususwa kwe-cC8═OOH kunye ne-PPh3 ukusuka kwi-Au + cC8═OOH-50, ukushiya u-Aun kunye ne-cC8═ engaphendulwanga, ayizange ithintele ukuguqulwa kwe-EB (thelekisa i-curves 1 kunye ne-2, i-Fig. 2).

Ezi seti zintathu zedatha zicebise i-synergism phakathi kwe-Aun kunye ne-cC8═ engaphendulwanga ekuqalisweni kwe-EB oxidation.Siye saqikelela ukuba uAun wenze i-oxidation ye-cC8═ ukwenza i-cC8═OOH, eyayingumqalisi we-EB reaction.Oku kunokuvavanywa ngokuthelekisa ukusebenza kakuhle kokuqaliswa kwe-EB oxidation kunye nomxube we-cC8═OOH kunye ne-cC8═ kodwa ngaphandle kwe-Aun ngaphambi nangemva kokususwa kwe-cC8═OOH kunye ne-PPh3.Ukulinganisa ngcono iimeko zeeseti zangaphambili zemifuniselo, sisebenzise isisombululo cC8═OOH-50 kumxube we-cC8═OOH kunye ne-cC8═ ukuze nasiphi na isiphumo esinokubakho se-cC8═ iimveliso ze-epoxidation ziya kuphinda ziveliswe.Iziphumo zibonise ukuba phambi kwe-cC8═OOH-50, i-EB iphendule ngokufanelekileyo (Umfanekiso 2, i-curve 4).Nangona kunjalo, ukuba i-cC8═OOH isuswe yi-PPh3, akukho mpendulo kwiyure yokuqala kunye nomsebenzi ocinezelweyo emva koko (i-curve 5).Ezi datha zixhasa ngakumbi imodeli yokuba indima ye-catalytic ka-Aun yayikukuqhuba ngokuqhubekayo i-cC8═OOH nge-cC8═ oxidation, kwaye i-cC8═OOH iqalise ukusabela kwe-EB.Indima ye-catalytic ka-Aun yaqinisekiswa ngakumbi ngokuqwalasela ukuba amazinga okuqala e-EB oxidation ngokungabikho kwe-cC8═OOH yanda ngokunyuka kwe-Aun concentration (fig. S3).

Indima eyodwa ka-Aun kule NCCS ibonakaliswe ngokuvavanya i-Co njengenye i-catalyst, eyakhethwa ngenxa yokuba i-cobalt acetate kunye ne-cobalt i-cycloalkanecarboxylate (13) zi-industrial catalysts zokuguqulwa kwe-EB kwi-acetophenone nge-molecular O2, esebenza phantsi kweemeko ezinzima kwaye ifuna ubukho be-asidi kunye ne-bromide ions.I-Co complexes nayo isetyenziselwa i-oxidation ye-aerobic EB ekhethiweyo phambi kwe-organocatalyst N-hydroxyphthalimide (NHPI) okanye i-reductant yedini (14, 15).Nangona kunjalo, phantsi kweemeko zethu zokusabela, ubukho be-Co/ZSM-5 abuzange bubangele nayiphi na i-oxidation ebonakalayo ye-EB, cC8═, okanye umxube wabo ubuncinane iiyure ze-6.Oko kukuthi, i-Co iyodwa ayikwazanga ukuqalisa ukusabela kwe-oxidation.Nangona kunjalo, kubukho buka-Aun kunye ne-cC8═, yenza lula ukusabela kwe-oxidation.Ngokuxhomekeke kwimeko, i-cC8═ okanye i-EB iphendule ngokuphindwe kathathu ukuya kahlanu ngokukhawuleza xa i-Co/ZSM-5 ikhona, kwaye uphuculo lwanda ngenani le-Co/ZSM-5 (itafile ye-S2, imifuniselo ye-6 ukuya kwi-8).Ukuhanjiswa kwemveliso ye-EB oxidation nako kuye kwatshintsha ngandlel' ithile phambi kwe-Co/ZSM-5.Ukwandisa inani le-Co / ZSM-5 kwandisa imveliso ye-acetophenone kwaye, kwinqanaba elingaphantsi, i-phenylethanol imveliso ngeendleko ze-EB hydroperoxide (itafile ye-S3, imifuniselo ye-6 ukuya kwi-8), ngokuhambelana nenyaniso yokuba i-Co catalyzed ukubola kwe-EB hydroperoxide ukuya. i-acetophenone kunye ne-phenylethanol kunye ne-oxidation yokugqibela kwi-acetophenone.Ngenxa yokulungela, sifake i-Co/ZSM-5 kumxube wethu wokusabela ukuze sinciphise ixesha lokusabela.

Into ephawulekayo phakathi kwe-NCCS kunye ne-tandem reaction systems kukuba ngaphambili, akukho budlelwane be-stoichiometric phakathi kweempendulo ze-A kunye ne-B (umzobo 1).Ukuqinisekisa ukuba iimpendulo zethu zenzeke nge-NCCS, siye savavanya isiphumo sokutshintsha umlinganiselo we-cC8═ ukuya kwi-EB ngokubeka iliso kwiireyithi zabo zokusabela.Umzobo we-3 ubonisa iziphumo zokutshintsha i-cC8═ yokuqala yoxinaniso ngelixa ugcina ugxininiso lokuqala lwe-EB kunye nezinye iimeko zokuphendula rhoqo.Idatha ibonisa ukuba akukho budlelwane obusisigxina be-stoichiometric phakathi kobuninzi be-reactants ezimbini baphendule, beqinisekisa ukuba ipateni yokusabela yahluke kwi-skim ye-tandem yokusabela yendabuko.Iseti efanayo yovavanyo apho ugxininiso lokuqala lwe-EB lwatshintshwa ngelixa kulungiswa ezinye izigxina zafika kwisigqibo esifanayo.Ukusuka kule datha, iireyithi zokuphendula zokuqala zibalwe (Itheyibhile 1 kunye netheyibhile ye-S2, iimvavanyo ze-4 kunye ne-5) kwaye iboniswe ukuba iyahluka ngokwahlukileyo kwi-cC8═ kunye ne-EB.Kwakungekho kurhwebelwano kumazinga okusabela phakathi kwezi mpendulo zimbini kangangokuba xa enye impendulo iqhubeleka ngokukhawuleza, enye kwafuneka icothe ngokomlinganiselo.Zombini iireyithi zokusabela zinokunyuka ngaxeshanye, njengoko kubonisiwe ngemifuniselo yesi-4 no-5 kwitheyibhile S2.Urhwebo luya kulindeleka ukuba i-EB ne-cC8═ zikhuphisana kwindawo enye ye-catalytic reaction okanye ephakathi.Esi sigqibo sikwangqinelana nento yokuba ukuphendulwa ngaxeshanye kwe-EB kunye ne-cC8═ kwakungekho okanye isiphumo esincinci kakhulu ekusasazeni imveliso nganye, njengoko kubonisiwe kwiThebhile 1 kunye netheyibhile S3.

I-cC8═ yokuqala yogxininiso yayiyi-0.34 M (A), 1.05 M (B), kunye ne-1.75 M (C).I-Decane yasetyenziselwa ukwenza umahluko kumthamo we-cC8═ osetyenzisiweyo.Ezinye iimeko: 32 mg yeCo/ZSM5, 100°C.

Ezi datha zihambelana neskimu soomatshini esiboniswe kwi-Fig 4, apho kugxininiswe amanyathelo abalulekileyo kwi-NCCS kwaye abadlali abaziinqununu bagxininiswe (isikimu esipheleleyo siboniswe kwifig. S8).Kulo matshini, amaqoqo e-Aun aqalisa umjikelezo we-cC8═ epoxidation ngokuvelisa i-cyclooctenyl radicals (I) kunye ne-cyclooctene peroxy radicals (II).Ezi radicals zimbini ke zithatha inxaxheba kumjikelo we-cC8═ we-epoxidation, njengoko wawusekiwe ngaphambili (2, 16).Xa i-EB ikhona, i-II iba yi-molecule ye-intermediary kunye ne-shuttles phakathi kwe-cC8═ i-epoxidation cycle kunye ne-EB oxidation cycle.Kumjikelo we-EB, i-II isabela kunye ne-EB ukwenza i-phenylethyl radical, eyenza ngokukhawuleza i-phenylethyl peroxy radical (III) ngokusabela nge-O2, njengoko i-carbon-centered radical reactions kunye ne-O2 iyaziwa ukuba ilula kakhulu (1).I-hydrogen abstraction elandelayo yi-III yenza i-phenylethyl hydroperoxide kwaye ekugqibeleni i-acetophenone kunye ne-phenylethanol.I-III inokuphinda iphendule ngokukhawuleza nge-cC8═, eba yindlela yokuzalisa i-II esetyenziswa ngumjikelo we-EB oxidation.Ke ngoko, i-EB oxidation reaction ayikhatshwa yi-stoichiometric suppression ye-cC8═ epoxidation reaction, kwaye akukho "trade-off" kwireyithi yokusabela ye-EB kunye ne-cC8═ njengoko bekuya kulindeleka ukuba bebekhuphisane kwi-reagent efanayo. okanye indawo esebenzayo ye-catalytic.Ngenxa yokuba i-II ithatha inxaxheba kwinyathelo lokuqalisa kuzo zombini i-EB kunye ne-cC8═ imijikelo ye-oxidation kodwa hayi ngokuthe ngqo kumanyathelo okwenziwa kwemveliso, ukudityaniswa kwayo kwezi mpendulo zimbini akuchaphazeli ukuhanjiswa kwemveliso.

I-Cyclooctene peroxy radical (II) ngumthetheli oyintloko oqalisa i-EB oxidation.II inokuvuselelwa ngokusabela kwe-EB peroxy radical (III) kunye ne-cC8═.Kumantla ekhohlo, amaqela e-Aun aqalisa umjikelo we-cC8═ we-epoxidation (umjikelo ngasekhohlo).Umjikelo osekunene ubonisa amanyathelo e-EB oxidation.Kuphela ngamanyathelo aziinqununu abalulekileyo kwi-NCCS aboniswayo.

Ukuqinisekisa ukubunjwa kwee-radical intermediates ezidlulayo njengoko kucetywayo kwi-Fig. 4, songeze i-spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) kumxube wokuphendula ukwenza i-nitroxide radical spin adducts ehlala ixesha elide kunye iiradicals zasimahla ezikhoyo ukuze zibonwe nge-X-band electron paramagnetic resonance (EPR) spectroscopy.Njengolawulo, akukho ma-radicals abanjwe yi-DMPO kwisisombululo se-acetone kunye ne-decane ngaphandle kwe-C8═ okanye i-EB (umkhiwane S4-3).Xa i-DMPO yongezwa kumxube wokusabela oqulethe i-cC8═OOH kunye ne-cC8═ (ifig. S4-1), isiphumo se-EPR spectrum safaniswa kakuhle njengesixa seentlobo ezinkulu ezahlukeneyo zeparamagnetic (A emfanekisweni, ~86% yetotali. ubukhulu bokulinganisa) kunye neentlobo ezimbini ezincinci (i-B kunye ne-C, i-5 kunye ne- ~ 9% ye-total intensity yokulinganisa, ngokulandelanayo), ukubonelela ubungqina obuthe ngqo bokwakheka okukhulu ngexesha lokuphendula.Ngokusekwe kuthelekiso lwexabiso lokudityaniswa kwe-hyperfine kulawo aziwayo e-DMPO adducts (itheyibhile S1), uhlobo C lwabelwa kwi-DMPO/ROO• adduct, ngokucacileyo i-cyclooctene 3-peroxy radical (II) eboniswa njengomlamli phakathi kwezi zimbini. iimpendulo (Fig. 4).Iintlobo zeentlobo ze-A kunye no-B zabelwa kwii-DMPO/RO• edityanisiweyo ezimbini ezahlukileyo, apho u-R ubhekiselele kwi-hydrocarbon moiety.Isenokuba yenye yeentlobo ze-RO• ezichazwe kwi-Fig. 4 okanye i-alkoxy radicals eveliswe kwi-DMPO/ROO• i-adduct decay [DMPO/ROO• adducts zaziwa ngokungazinzanga kwaye zibole kwi-alkoxy radical adduct ehambelanayo (17, 18)] okanye umxube wazo zombini.Xa i-EB iphinda ibandakanywe kumxube wokusabela, isiphumo se-EPR silinganiswe kakuhle nesininzi seentlobo ze-A′, eyayifana kakhulu neentlobo ze-A (DMPO/RO•), kunye neentlobo ezimbini ezincinci ze-B kunye no-C ezineminikelo emincinci efanayo. (umzobo S4-2 kunye netafile S1).Ngenxa yokuba ukufakwa kwe-EB bekulindeleke ukuba kuqhube ukuyilwa kwephenylethyl peroxy radicals (III), iintlobo ze-A′ kusenokwenzeka ukuba ngumxube we-RO• uveliswe kwimpendulo kunye nayo nayiphi na i-phenylethyl peroxy adduct, eyathi emva koko yabola kwi-phenylethyl oxy DMPO adduct.

Ukusebenzisa i-EB-d10 njenge-reactant kunye nokubeka iliso kwi-deuterium eyileyibhile kwiimveliso ze-cC8═ inokubona ukuba kukho ukusabela kwe-EB nge-cC8═ esekelwe kwi-carbon radicals.Iziphumo zovavanyo olunjalo zibonise ukuba akukho deuterium incorporation kwi-cyclooctene epoxide (amakhiwane S5 kunye ne-S6).I-Phenylethanol igcine yonke i-deuterium kwi-reactant ye-EB, kwaye ezinye ze-deuterons kwiqela le-methyl ye-acetophenone ziye zatshintshisana, ezinokuthi zenzeke kwi-mass spectrometer.Ke, akukho bungqina bokusabela phakathi kwe-EB-d10 kunye ne-cyclooctenyl radical, eya kwazisa i-deuteron kwiimveliso ze-cC8═.

Ukusetyenziswa kwesicwangciso se-NCCS kwandiswe ukuhlola i-Au + cC8═OOH-100-incedise i-aerobic oxidation ye-4-methylanisole.Ngenxa yeebhondi eziphambili ze-C─H kule molekyuli, impendulo ye-oxy-functionalization yenziwa kwiqondo lokushisa eliphezulu.Amazinga okuqala okuguqulwa kwe-4-methylanisole ukuya kwi-4-anisaldehyde yafaniswa neempendulo eziqaliswe kunye no-Aun kwaye mhlawumbi kunye okanye ngaphandle kwe-cC8═ ukongeza (cC8═OOH isuswe nge-PPh3).Ngokufana ne-EB oxidation, xa umxube wokusabela ungenayo i-cC8═ kwaye akukho cC8═OOH, izinga lokuqala le-oxidation lalicotha kakhulu (fig. S7).Xa i-cC8═ yongezwa kumxube wokusabela, isantya sokuqala se-oxidation sandiswa ngokubonakalayo.Ngaloo ndlela, amaqela e-Aun akwazi ukuvelisa i-cC8═OOH ukusuka kwi-cC8═ eyongezelelweyo ukuqalisa i-oxidation ye-4-methylanisole njengoko kulindelwe kwi-NCCS.

Ukuqukumbela, sibonise ingcamango ye-NCCS.Ukusebenzisa i-oxidation ngaxeshanye ye-cyclooctene kunye ne-EB kunye ne-cyclooctene kunye ne-4-methylanisole, i-NCCS iboniswe ukwenza i-co-oxidation ye-hydrocarbons ngaphandle kwemithintelo yobudlelwane be-stoichiometric yeenkqubo ze-co-oxidation zendabuko.Oku kunika iqondo lenkululeko ebingafumanekiyo ngaphambili kushishino olunje ukuba uqoqosho lwenkqubo alusabotshelelwa yimfuneko yeemarike ezincomekayo zeemveliso ezenziwe ngezixa-mali ze-stoichiometric.

Imithombo kunye nokuhlanjululwa kweekhemikhali ezisetyenzisiweyo zilandelayo: HAuCl4•3H2O (≥99.9% isiseko sesinyithi sokulandelela, i-Sigma-Aldrich), i-silica evuthayo (i-CAB-O-SIL90, i-Cabot Corporation), i-ethylenediamine (≥99% ReagentPlus, i-Sigma-Aldrich) , i-ethanol (i-200 grade, i-Decon Labs), i-cobalt (II) i-nitrate hexahydrate (≥98%, i-Sigma-Aldrich), i-Nano H-ZSM-5 (P-26, i-ACS Material), i-decane (≥99% ReagentPlus, i-Sigma- Aldrich), dodecane (≥99% ReagentPlus, Sigma-Aldrich), cis-cyclooctene (95%, Alfa Aesar), EB (99.8% anhydrous, Sigma-Aldrich), EB-d10 (99 atomic % D, Sigma-Aldrich) , 4-methylanisole (99%, Sigma-Aldrich), acetophenone (99% ReagentPlus, Sigma-Aldrich), 1-phenylethanol (98%, Sigma-Aldrich), i-hydrogen peroxide (30% isisombululo samanzi, iFisher Chemical), i-potassium hydroxide (ibakala le-reagent, i-90%, i-Sigma-Aldrich), i-sodium sulfate (i-Codex yeMichiza yoKutya/i-United States i-Pharmacopeia–grade, i-Fisher Chemical), i-tetrahydrofuran (> 99%, i-Sigma-Aldrich), i-tert-butyl hydroperoxide (~5.5 M kwi-decane , Sigma-Aldrich), Ph3 (> 98.5%, Sigma-Aldrich), d-chloroform (99.8 atomic % D, Sigma-Aldrich), HCl (38% w / w, Fisher Chemical), HNO3 (68 ukuya kwi-70% w / w, i-Fisher Chemical), i-EM Quant peroxide imicu yokuvavanya, kunye nesihluzo sesirinji (i-polyvinylidene difluoride membrane, 0.25 mm / 0.2 μm, i-Acrodisc).

Au/SiO2.I-silica-inkxaso yegolide ye-nanoparticle catalyst yalungiswa nge-Au (en) 2Cl3 isandulela ngokwendlela eyenziwe nguZhu et al.(19) kwaye iguqulwe nguQian et al.(2).Ukucacisa ngakumbi, isisombululo se-Au (III) chloride trihydrate salungiswa ngokuchithwa kwe-0.5 g ye-HAuCl4•3H2O kumxube oqukethe i-10 ml ye-ethanol kunye ne-2 ml yamanzi.Emva kokwenza isisombululo se-homogeneous, i-0.23 ml ye-ethylenediamine (en = ethylenediamine) yongezwa kwisisombululo se-dropwise ukwenza i-Au (III) ethylenediamine chloride [Au (en) 2Cl3] ngokutshintshiselana kwe-ligand.I-Au(en) 2Cl3 eyenziwe njenge-formed yaqokelelwa ngokuhluzwa kwaye ihlanjwe nge-300 ml ye-ethanol.Ukufaka i-Au kwinkxaso ye-silica, i-4.2 mM Au(en)2Cl3 isisombululo samanzi salungiswa ngokunyibilikisa i-46.3 mg ye-Au (en) 2Cl3 kwi-26 ml yamanzi adibeneyo adiyiweyo (DDI).Isisombululo esenziwe njengenziwe sagcinwa kwi-40 ° C kwindawo yokuhlambela ioli.Emva koko, i-1 g ye-silica evuthayo yongezwa kwisisombululo esandulelayo ngelixa uvuselela.Emva kokuba zonke izixhaso ze-silica zifakwe kwisisombululo, umxube wasuswa kwi-oyile yokuhlambela kwaye upholile kwiqondo lokushisa.Ngokuhlenga-hlengisa i-pH yomxube ukuya kwi-9 kunye nokongeza kwi-dropwise ye-0.75 M en i-aqueous solution, i-adsorption engcono ye-cationic iikhompleksi zegolide kumphezulu ochajiweyo kakubi kuye kwaphunyezwa.Emva kokuvuselela iiyure ze-2 kwiqondo lokushisa, umxube wawuhluzwa kwaye uhlanjwe nge-500 ml yamanzi e-DDI.Ukususa iintsalela ezingafunekiyo (Cl, en, obunye ukungcola), ikeyiki yokucoca yaphinda yachithwa kwi-200 ml yamanzi e-DDI kwi-40 ° C.Ekugqibeleni, i-Au / SiO2 eyenziwe njenge-formed yaqokelelwa ngokucoca kwaye ihlanjwe kunye nenye i-500 ml yamanzi e-DDI kwaye yomiswe emoyeni ngobusuku bonke.Ukubalwa kwe-silica-inkxaso ye-nanoparticles ye-catalyst yegolide yenziwa kwi-U-tube phantsi kwe-O2 / O3 flow (~ 300 ml / min) kunye nesantya sokunyuka kwe-0.12 ° C / min ukuya kwi-150 ° C.I-catalyst igcinwe ebumnyameni kwi-5 ° C.Ukulayishwa kwegolide, njengoko kubalwa nge-inductively plasma optical emission emission spectrometry, yayisisi-1.2 sobunzima be-% (wt%), kunye ne-avareji yesayizi yamasuntswana egolide alinganiswa ngokuskena i-electron microscopy (STEM) yayimalunga ne-2 nm.

Co/ZSM-5.I-Nano H-ZSM-5 i-calcined kwi-U-tube phantsi kwe-O2 / O3 ukuhamba (~ 300 ml / min) kunye nesantya se-2 ° C / min ukuya kwi-200 ° C kwaye ibanjwe kwi-200 ° C ngeyure ye-1 ukususa. iitemplates ezishiyekileyo.I-Co/ZSM-5 yalungiswa bubumanzi bokuqala.Ngokomzekelo, i-5 wt % yokulayisha i-Co/ZSM-5 yalungiswa ngokongeza i-0.72 M cobalt (II) isisombululo se-nitrate [250 mg ye-cobalt (II) i-nitrate hexahydrate kwi-1.2 ml yamanzi e-DDI] kwi-1 g ye-nano H- I-ZSM-5 ngelixa ujikeleza ngononophelo i-beaker.I-slurry yomiswa phantsi kwesibane, kwaye i-pink powder efanayo yenziwa.I-powder-formed powder yabe ilayishwa kwi-tube yokubala ngokuthe tye kwaye ihlanjululwe phantsi kwe-argon flow (100 ml / min) ngeyure ye-1 ukunciphisa umswakama.I-catalyst elungiselelwe njenge-calcined phantsi kwe-oxygen flow (60 ml / min) kunye nesantya se-ramping ye-10 ° C / min ukuya kwi-450 ° (ebanjwe kwi-250 ° C, 350 ° C, kunye ne-450 ° C ngeyure ye-1 nganye) .I-Co/ZSM-5 efunyenweyo inomthwalo we-cobalt we-5 wt%.Ezinye izinto ezimbini ezilayishiweyo, 3 kunye ne-7 wt %, nazo zalungiswa.Zontathu ii-catalysts zibonakaliswe ngokuncipha kwenkqubo yobushushu be-H2, i-x-ray diffraction, i-x-ray photoelectron spectroscopy, kunye ne-ultraviolet-visible spectroscopy.

I-Au-equlathe isihluzo.I-Au-containing filtrate (Au + cC8═OOH-x) yayikwi-situ yenziwe kwi-Au/SiO2-catalyzed cC8═ reaction epoxidation ngokwenkqubo eyenziwe nguQian et al.(2) Ngaphambi kokusabela, i-cC8═ yahlanjululwa ukuze isuse umenzi-wongeza uzinzo.Ngokuqhelekileyo, i-50 ml ye-3 M isisombululo se-potassium hydroxide (KOH) yongezwa kwi-50 ml ye-cC8═ kwi-flask.Emva kokuxuba okwaneleyo kunye nokuvuselela ngamandla, i-organic layer yaqokelelwa ngokuhlukana.Le nkqubo iphindwe enye i-50 ml ye-3 M KOH kunye nezinye ezimbini ze-50 ml zamanzi e-DDI.I-cC8═ emva koko yomiswa nge-sodium sulfate ngobusuku.Ukususa ngokupheleleyo i-stabilizer, i-cC8═ eyomileyo yachithwa kwindawo yokuhlambela ioli malunga ne-180 ° C, kwaye iqhekeza eliphuma kwi-145 ° C liqokelelwe.I-cC8═ ecocekileyo (10 ml) kunye ne-decane (1 ml) yaxutywa kwi-reactor equlethe i-80 mg ye-Au/SiO2 catalyst ekhankanywe ngasentla.I-cC8═ i-epoxidation reaction yenziwa phantsi kwe-oxygen flow (30 ml / min) kwi-100 ° C, kwaye ukuguqulwa kwakubekwe esweni yi-GC.Nje ukuba uguqulo olufunwayo lufikelelwe, umxube wokusabela uqokelelwe kwaye i-catalyst eqinileyo yasuswa ngokucoca okushushu kusetyenziswa isihluzo sesirinji.Ugxininiso oluqhelekileyo lwe-Au olunyibilikisiweyo oluye lwamiselwa yi-plasma mass spectrometry edityanisiweyo yayimalunga ne-80 ng/ml, kwaye ubungakanani beqela le-Au lamiselwa yi-fluorescence spectroscopy kunye ne-aberration-corrected transmission electron microscopy ukusuka kwi-Atom ye-Au ukuya kwi- ~0.7 nm.cC8═OOH-x yalungiswa ngokufanayo ngaphandle kokusebenzisa i-Au/SiO2 catalyst.Zombini i-Au + cC8═OOH-x kunye ne-cC8═OOH-x izisombululo eziqulethwe yi-cC8═ iimveliso ze-oxidation, ezibandakanya i-cyclooctene oxide, i-cyclooctene 3-hydroperoxide, i-2-cycloocten-1-ol, i-2-cycloocten-1-enye, kunye nokulandelela imali ye-1,2-cyclooctanediol.

Inkqubo ngokubanzi.I-EB oxidation reactions yenziwa ebumnyameni kwi-reactor ene-cylindrical ene-necked three-neck cylindrical reactor ene-fine frit glass disperser tube (Chemglass Life Sciences) kunye necondenser egcinwe ku-−10°C.Kwimpendulo eqhelekileyo, i-7 ml ye-EB, i-1 ml ye-decane, kunye ne-3 ml ye-filtrate (Au + cC8═OOH-x okanye i-cC8═OOH-x) zilayishwe kwi-reactor kunye ne-Teflon-coated magnetic stirrer.Ukuba isetyenzisiwe, kongezwa i-32 mg ye-5% Co/ZSM-5, ngaphandle kokuba kuchazwe ngenye indlela.Emva kokuba i-reaction setup ihlanganiswe, umxube wokuphendula uzinzile phantsi kwe-N2 ukuhamba kwe-20 min kwindawo yokuhlambela ioli eshushu.Emva kokuba iqondo lokushisa le-condenser kunye ne-oyile lizinzile, ukuhamba rhoqo kwe-O2 kwanikezelwa kwi-30 ml / min.Umxube wokusabela (0.1 ml) wathathwa ngamaxesha ahlukeneyo okuhlalutya (isihluzo sesirinji sasetyenziswa xa iicatalysts eziqinileyo zabandakanyeka), sanyibilikiswa kwi-0.7 ml ye-d-chloroform, kwaye yahlalutywa yi-1H nuclear magnetic resonance (NMR).

Ukuchongwa kwemveliso kunye nobungakanani.I-Aliquots yomxube we-reaction yahlanjululwa nge-tetrahydrofuran kwaye yahlalutywa nge-gas chromatography-mass spectrometry (GC-MS; i-Agilent GC-7890A, MS-5975).Ukusabela kwe-EB, i-acetophenone kunye ne-1-phenylethanol zachongwa njengezona mveliso zibalaseleyo.I-1H-NMR kunye ne-13C-NMR (i-400 MHz Agilent DD2-MR400 inkqubo) zisetyenziselwe ukuqhubela phambili ukuqinisekiswa kweempawu zemveliso.I-1-Phenylethyl hydroperoxide, engazange ibonwe yi-GC-MS ngenxa yokungazinzi kwayo kwe-thermal, ichongiwe yi-NMR ukuba ibe enye imveliso evelele.Zonke zintathu iimveliso zilinganiswe ngu-1H-NMR usebenzisa i-decane njengomgangatho wangaphakathi (umzobo S1).Ilahleko engumphunga yamiselwa ngokwahlukeneyo kwaye isetyenziselwa ukulungisa ukugxilwa kwemveliso.Emva kokulungiswa kweelahleko zomphunga, akukho kungalingani kwekhabhoni kuye kwajongwa kwi-EB reaction.Ukuphendula kwe-cyclooctene, i-cyclooctene oxide, i-cyclooctane-1,2-diol, i-2-cycloocten-1-ol, kunye ne-2-cycloocten-1-enye iqikelelwe yi-GC.I-Cyclooctene i-3-hydroperoxide ayizange izinzile kwaye ibolile kwikholamu ye-GC kwaye ngoko ayibonwa.Kwakukho malunga ne-10% yelahleko yekhabhoni ekuguquleni okupheleleyo nasemva kokuhlawula ilahleko ephumayo, enokuthi ichazwe ngokuqulunqwa kwexabiso elincinci leemveliso ezingaziwayo ezixutywe nge-oxidized.

Uguqulo kunye nokubala ukukhetha.I-GC okanye i-NMR yendawo yomlinganiselo we-molecule yomdla kwi-decane yangaphakathi yangaphakathi isetyenziswe ukubala ukuguqulwa kunye nokukhetha.Nangona i-condenser yokupholisa yayisetyenzisiwe, kwakuseyimfuneko ukubuyisela ilahleko engumphunga ngenxa yobushushu obuphezulu bokusabela kunye nexesha elide lokusabela.Iigophe zolungiso zomphunga ziye zafunyanwa kuzo zombini i-EB kunye ne-cC8═ phantsi kwenitrogen ehambayo kwaye iqhelekile kumlinganiselo we-EB/decane okanye cC8═/decane.Ngenxa yokuba i-EB kunye ne-cC8═ zineendawo zokubilisa ezifanayo, izinto zolungiso eziqhelekileyo ezifunyenweyo zombini ziyi-0.0044 (umlinganiselo oqhelekileyo wehla ngeyure).

Ubungakanani behydroperoxide.Ukuxinwa kwe-hydroperoxide kwalinganiswa ngeendlela ezimbini zokulinganisa:

1) I-Triphenylphosphine (PPh3) i-titration.I-PPh3 (i-0.1 M kwi-EB) yayisetyenziselwa ukulinganisa iisampuli ze-hydroperoxide ezingaziwayo, kwaye isiphelo sachongwa nge-EM Quant peroxide strip test.I-31P-NMR yayisetyenziselwa ukuqinisekisa ukususwa ngokupheleleyo kweentlobo ze-hydroperoxide.

2) I-iodometric titration.Isampuli (0.2 ml) ixutywe kunye ne-1 ml ye-CHCl3 / i-acetic acid (v / v = 1: 2) kunye ne-6 ml yesisombululo se-1 M KI.Umxube waxutywa ebumnyameni ngeeyure ze-2 waza waxutywa nge-0.005 M Na2S2O3 phambi kwamathontsi ambalwa esisombululo sestatshi.Isiphelo safikelelwa xa umxube wawungenambala.

Zombini iindlela zazihambelana ngaphakathi;nangona kunjalo, iziphumo zabo zohluke nge-5 ukuya kwi-10%.Ngenxa yokuba i-Au + cC8═OOH-x kunye ne-cC8═OOH-x esetyenzisiweyo kule projekthi yenziwe nge-cC8═OOH-iqaliswe nge-oxidation, i-hydroperoxide concentration yahlukile ukusuka kwibhetshi ukuya kwibhetshi kodwa yayihlala iphakathi koluhlu lwe-0.2 ukuya kwi-0.5 M yokulungiswa okusanda kulungiswa. cC8═OOH-40 ukuya kwi-cC8═OOH-100 iisampulu.Uxinzelelo lwe-hydroperoxide luye lwancipha ngokuhamba kwexesha.

EPR spin trap imifuniselo.I-DMPO (i-23 μl) yongezwa kwi-1 ml yesampuli ukufikelela kwi-DMPO yoxinaniso lwe-0.2 M, kunye ne-20 mg ye-Co / ZSM-5 yongezwa kumxube wesampuli kwi-tube yokuvavanya.Umxube wawufakwe kwi-1 min ukumisa i-catalyst, kwaye oku kwalandelwa ukufudumeza kwi-60 ° C kwi-~ 10 min.I-aliquot yomxube idluliselwe kwi-tube ye-borosilicate ye-tubing ye-capillary ejikelezayo (i-1.50 ngaphakathi kwe-diameter × 1.80 ngaphandle kwe-diameter, i-Wale Apparatus), eyayivalwe kwelinye icala-le bhubhu yabe ifakwe kwi-tube ye-Wilmad quartz X-band EPR. Sigma-Aldrich).Isampulu yakhenkcezwa ngokuntywiliselwa ityhubhu ye-EPR kulwelo lwe-N2.Ngokukhawuleza ngaphambi kokulinganisa i-spectra ye-EPR, isampuli yanyibilika.Imilinganiselo ye-EPR eqhubekayo (CW) ye-X-band ye-EPR yenziwa kwiqondo lokushisa kwigumbi kwi-spectrometer eguquliweyo ye-Varian E-4 usebenzisa umnwe uDewar.

Umfuniselo wokuleyibheli we-Isotopic.I-Deuterated EB (d10-EB) isetyenziswe kuvavanyo lomxube we-6 ml ye-cC8═OOH-45, i-5 ml ye-d10-EB, i-1 ml ye-decane, kunye ne-60 mg ye-Co-ZSM-5 (7%). , kwi-120 ° C, kunye ne-6 ml ye-cC8═OOH-45, i-5 ml ye-EB-d10, kunye ne-1 ml ye-dodecane.Ukubuyisela ukuhla kwesantya sokuphendula ngenxa ye-kinetic isotope effect, i-co-oxidation yenziwa kwiqondo lokushisa eliphezulu le-120 ° C.I-Aliquots yesampuli ithathwe ngaphambi nangemva kweeyure ze-24 zokuphendula kwaye zihlalutywe yi-2H-NMR kunye ne-GC-MS.

I-spectrum ye-2H-NMR (ifig. S5, i-spectrum 2) ibonise iincopho ezintsha ezininzi emva kokusabela, ezingekho phambi kokusabela, ku-δ1.50, δ1.58, δ4.94, δ7.42 ukuya ku-δ7.72, kunye ne-δ8.04 .Ngenxa yokunciphisa i-J-coupling rhoqo kunye novelwano lwe-2H-NMR, iipatheni zokuqhawula azizange zisonjululwe.Iincopho e-δ8.04 kunye ne-δ7.42 ukuya ku-δ7.72 zabelwa iideuteron zeringi enevumba elimnandi ye-acetophenone;iincopho ze-δ1.50 kunye ne-δ4.94 zabelwa i-methyl kunye ne-benzylic deuteron ye-1-phenylethanol, ngokulandelanayo;kunye nencopho e-δ1.58 yabelwa i-deuteron kwi-D2O eyenziwe ngokubola kwe-hydroperoxide.Akukho deuteron efunyenwe ehambelana neemveliso ze-cyclooctene epoxidation, kwaye ukubunjwa kwamanzi ahlanjululwayo kubonise ukuba abathwali be-radical chain eziphambili kwi-co-oxidation reaction babeyi-peroxy kunye ne-alkoxy.

Imbonakalo ye-GC-MS yeemveliso iboniswe kwifig.S6.I-Acetophenone-d8 (m/e 128, deuterated ngokupheleleyo, umkhiwane S6A, m/e 127 kunye ne-126) yabonwa.Ukususela kwipatheni yokuqhaqha, yonke i-HD itshintshiselwano yenzeke kwindawo ye-methyl.Ukongeza, i-1-phenylethanol-d9 (m/e 131) (ifig. S6B) yayikuphela kweemveliso ezifunyenweyo.Akukho deuterium efunyenwe kwi-cyclooctene oxide (umkhiwane. S6C), eyona mveliso ininzi kakhulu evela kwi-cyclooctene epoxidation.I-1-Phenylethanol-d9 inokwakheka ngokusabela kwe-phenylethoxy radical kunye ne-cyclooctene.

Imathiriyeli eyongezelelweyo yeli nqaku iyafumaneka ku-http://advances.sciencemag.org/cgi/content/full/6/5/eaax6637/DC1

Umzobo S5.I-2H-NMR ngaphambi (i-spectrum 1, ebomvu) nasemva (i-spectrum 2, eluhlaza) i-24-hour co-oxidation reaction.

Umzobo S7.Ukuthelekiswa kokuguqulwa kokuqala kwe-4-methyl anisole eqaliswe ngokusebenzisa i-Au + cC8═OOH-100, kunye ne-cC8═OOH isusiwe.

Eli linqaku elivulekileyo lokufikelela lisasazwe phantsi kwemiqathango yelayisensi ye-Creative Commons Attribution-NonCommercial, evumela ukusetyenziswa, ukuhanjiswa, kunye nokuveliswa kwakhona kuyo nayiphi na indlela, okoko nje ukusetyenziswa okubangelwayo kungeyonzuzo yorhwebo kwaye ibonelele umsebenzi wokuqala ngokufanelekileyo. icatshulwe.

QAPHELA: Sicela idilesi yakho ye-imeyile kuphela ukuze umntu omcebisayo eli phepha azi ukuba ubufuna alibone, kwaye asiyoimeyile eyinkunkuma.Asithathi nayiphi na idilesi ye-imeyile.

NguAnyang Peng, uMayfair C. Kung, uRobert RO Brydon, uMateyu O. Ross, uLinping Qian, uLinda J. Broadbelt, uHarold H. Kung

Kwinkqubo ye-catalytic ye-noncontact, abalamli abavela kwi-Au-catalyzed cyclooctene epoxidation effects ethylbenzene oxidation.

NguAnyang Peng, uMayfair C. Kung, uRobert RO Brydon, uMateyu O. Ross, uLinping Qian, uLinda J. Broadbelt, uHarold H. Kung

Kwinkqubo ye-catalytic ye-noncontact, abalamli abavela kwi-Au-catalyzed cyclooctene epoxidation effects ethylbenzene oxidation.

© 2020 Umbutho waseMelika wokuPhucula iNzululwazi.Onke Amalungelo Agciniwe.I-AAAS ngumlingane we-HINARI, i-AGORA, i-OARE, i-CHORUS, i-CLOCKSS, i-CrossRef kunye ne-COUNTER.I-Science Advances ISSN 2375-2548.