Mwachikhalidwe, chothandizira chimagwira ntchito polumikizana mwachindunji ndi ma reactants.Mu new nocontact catalytic system (NCCS), njira yapakatikati yopangidwa ndi imodzi yochititsa chidwi imagwira ntchito ngati mkhalapakati kuti athe kuchitapo kanthu paokha.Chitsanzo ndi makutidwe a okosijeni osankhidwa a ethylbenzene, omwe sakanatha kupezeka pamaso pa ma solubilized Au nanoclusters kapena cyclooctene, koma anapitirira mosavuta onse analipo nthawi imodzi.The Au-initiated selective epoxidation ya cyclooctene yopangidwa ndi cyclooctenyl peroxy ndi oxy radicals yomwe idakhala ngati amkhalapakati kuti ayambitse okosijeni wa ethylbenzene.Dongosolo lophatikizanali lidakulitsa mphamvu ya Au.Njira yochitirayi idathandizidwa ndi kuyesa kwa kinetics ndi spin trap.NCCS imathandizira machitidwe ofanana kuti apitirire popanda zopinga za maubwenzi a stoichiometric, kupereka magawo atsopano a ufulu mu njira zamafakitale za hydrocarbon co-oxidation.

Mwachizoloŵezi, chothandizira chimagwirizana mwachindunji ndi ma reactants (action A) kuti athetse kukonzanso zomangira zomwe zimaperekedwa ndi zomwe zimachitika.Mwachitsanzo, mu cobalt-catalyzed makutidwe ndi okosijeni wa alkylaromatics (1) kapena Au-catalyzed epoxidation wa cyclooctene (2), chothandizira facilitates abstraction wa atomu haidrojeni ku hydrocarbon kuyambitsa zimene.Pakuchita ma radical chain aulere, chothandizira chimatenga nawo gawo pakugawanikana kofooka kwa homolytic kwa oyambitsa omwe amawonjezedwa mwadala kapena kupezeka ngati zonyansa zomwe zimapangidwira pakusakanikirana (1, 3, 4).Masitepe ena panjira yothandiza kwambiri sangafunikire kulumikizana mwachindunji ndi gawo lapansi pomwe kusintha kwa gawo lapansi kumathandizidwa ndi zinthu zomwe zapangidwa mochititsa chidwi m'magawo apitawa (5-8).Komabe, machitidwewa amakakamizidwa ndi ubale wa stoichiometric pakati pa masitepewo.Mwachitsanzo, mu Mukaiyama (ep) oxidation ya alkene, chothandizira chimatembenuza chotsitsa cha nsembe mukuchita A, monga isobutyraldehyde, ndi mapangidwe a stoichiometric a epoxide (reaction B) (9, 10).Ngakhale kuti n'zotheka kwenikweni, sitikudziwa chitsanzo chomwe ntchito ya chothandizira ndi kupanga S yapakatikati pochita A, pamene S imakhala ngati mkhalapakati kuti ayambe kapena kuyambitsanso zina B m'malo mochita nawo monga stoichiometric reagent. , pamene chothandizira sichigwira ntchito pakuchita B (mkuyu 1).Izi chiwembu, chikoka cha chothandizira ndi anawonjezera kupitirira catalyzing anachita A kuti nawonso anachita anachita B koma popanda kukhudzana mwachindunji ndi reactants.Chiwembu choterechi timachitcha kuti Nocontact Catalytic System (NCCS).Mu NCCS, kukula kwa machitidwe A ndi B sikumangika ndi ubale uliwonse wa stoichiometric pakati pawo.Izi zikusiyana ndi zochitika za tandem.M'makampani, ubale woterewu wa stoichiometric nthawi zambiri umabweretsa zovuta zachuma pakupanga mankhwala.Chitsanzo chodziwika bwino ndi kupanga stoichiometric kwa phenol ndi acetone pogwiritsa ntchito okosijeni wa benzene kudzera pa cumene hydroperoxide wapakatikati mu cumene process (11).

Chothandizira (Mphaka) chimayambitsa machitidwe A (AR ➔ S ➔AP) momwe S apakati amagwira ntchito poyambitsa kapena kuyambitsa B (BR ➔ BP), ngakhale kuti B sakhudzidwa ndi chothandizira.

Tidapeza NCCS yotereyi poyang'ana zinthu zothandiza zamagulu a solubilized Aun (pomwe n anali maatomu asanu ndi limodzi mpaka asanu ndi atatu) a okosijeni pang'ono a ethylbenzene (EB).Tawonetsa kuti awa osungunula Aun adathandizira kukhazikitsidwa kwa kusankha epoxidation ya cyclooctene (cC8═) ndi O2 yokhala ndi ~ 80% kusankha (2).Maguluwa adapangidwa mu situ nthawi ya Au/SiO2-catalyzed cC8═ epoxidation, ndipo adasunga luso lawo lopanga radical initiator cyclooctene hydroperoxy radical (cC8═OO·) panthawi yonseyi.Magulu osungunuka a Aun amatha kusonkhanitsidwa munjira yosakanikirana atachotsedwa Au/SiO2, ndipo kukula kwake kwapakati kumatsimikiziridwa pogwiritsa ntchito ma electron microscopy ndi fluorescence spectroscopy (2).Kuphatikiza pa magulu a Aun, zosakanizazi zinalinso ndi cyclooctene hydroperoxide (cC8═OOH) ndi zinthu zotulutsa okosijeni cyclooctene epoxide, cyclooctenol, ndi cyclooctenone.cC8═OOH inali mtundu wokhazikika wa hydrogenated wa cC8═OO· ndipo umapezeka pamagulu a 0.2 mpaka 0.5 M pambuyo pa kutembenuka kwa 40 mpaka 100% cC8═.Kusakaniza kumeneku kumatchedwa Au + cC8═OOH-x, pamene x ndi peresenti cC8═ kutembenuka.Ngakhale pamlingo wocheperako komanso nthawi yayitali (> 5 maola) induction, cC8═ epoxidation imathanso kuchitika ndi auto-oxidation popanda magulu a Aun.Zosakaniza zopezedwa ndi auto-oxidation popanda Au zimatchedwa cC8═OOH-x.Mu NCCS, Aun yosungunuka ingakhale chothandizira, epoxidation ya cC8═ idzakhala reaction A, ndipo cC8═OO· idzakhala S.

The auto-oxidation ya EB sikuchitika mosavuta.Pa 145 ° C, 9% yokha idachitika chifukwa cha EB yabwino pansi pa 2.76 MPa O2 (12).Pansi pamikhalidwe yathu yofatsa kwambiri ya 100 ° C ndi kuphulika kwa O2 pa 0.1 MPa, panalibe mawonekedwe owoneka bwino a EB kwa maola osachepera 20.Kuwonjezedwa kwa free radical initiator kunali kofunikira kuti izi zipitirire.Kuyambitsa ndi 2,2'-azobisisobutyronitrile (AIBN), woyambitsa kwambiri matenthedwe amphamvu kwambiri, adayambitsa auto-oxidation ya EB yokhala ndi unyolo wapakati wa ~ 3 (mkuyu S2A).Unyolo waufupi (~1) udawonedwa pogwiritsa ntchito tert-butyl hydroperoxide (mkuyu. S2B), ndipo panali kachitidwe kakang'ono kozindikirika pogwiritsa ntchito cumene hydroperoxide yochepa kwambiri.Chifukwa chake, auto-oxidation ya EB inalibe mphamvu zochepa pazotsatira zomwe zafotokozedwa pansipa.

Kukhazikika kwa aerobic oxidation ya EB kupita ku EB hydroperoxide, acetophenone, ndi phenylethanol kunapezedwa powonjezera Au + cC8═OOH-50 yomwe ili ndi chisakanizo cha Aun, cC8═OOH, ndi cC8═ yosasinthika (Mkuyu 2, curve 1).Monga momwe zasonyezedwera ndi mayesero otsatirawa, zigawo zitatuzi zinagwira ntchito yaikulu mu EB oxidation, ndipo zimayenderana ndi chothandizira, S, ndi AR mu dongosolo la NCCS lowonetsedwa mu Fig.

(i) 7 ml ya EB + 3 ml ya Au + cC8═OOH-50;(ii) 7 ml ya EB + 3 ml ya Au + cC8═OOH-50 + 1.2 mmol Ph3;(iii) 7 ml ya EB + 3 ml ya Au + cC8═OOH-99 + 0.6 mmol Ph3;(iv) 7 ml ya EB + 3 ml ya cC8═OOH-50;(v) 7 ml ya EB + 3 ml ya cC8═OOH-50 + 1.5 mmol Ph3.Kuchuluka kwa PPh3 yowonjezeredwa idayikidwa kuti ikhale yofanana ndi kuchuluka kwa titrated hydroperoxide (kutentha kwamachitidwe, 100 ° C).

Pansi pamikhalidwe yathu, palibe makutidwe ndi okosijeni a aerobic EB omwe adachitika mosakanizika cC8═ ndi EB (ie, popanda Cat kapena S).Triphenylphosphine (PPh3) imathandiza kwambiri kuchotsa hydroperoxides.Yankho la Au + cC8═OOH-99, latha cC8═OOH ndi Pph3 kuwonjezera, lomwe linali ndi Aun ndi cC8═ yochepa kwambiri yosakhudzidwa, silinayambe kuyambitsa EB ngakhale pambuyo pa maola 2 (Mkuyu 2, curve 3), kusonyeza kuti Aun chokhacho chinali chosagwira ntchito.Chotsatirachi chinasonyezanso kuti zinthu zina za cC8═ oxidation, monga cyclooctene epoxide, cyclooctene mowa, kapena ketone, sizinathe kuyambitsa EB oxidation.Mosiyana ndi kuyesera pamwambapa, kuchotsa cC8═OOH ndi Pph3 kuchokera ku Au + cC8═OOH-50, kusiya Aun ndi cC8═ osakhudzidwa, sikunalepheretse kutembenuka kwa EB (yerekezerani ndi ma curve 1 ndi 2, Fig. 2).

Maseti atatu awa a data adalimbikitsa mgwirizano pakati pa Aun ndi cC8═ yosakhudzidwa poyambitsa EB oxidation.Tidayerekeza kuti Aun adayambitsa ma oxidation a cC8═ kupanga cC8═OOH, omwe adayambitsa EB reaction.Izi zitha kuyesedwa poyerekeza mphamvu yoyambitsa makutidwe a okosijeni a EB ndi chisakanizo cha cC8═OOH ndi cC8═ koma popanda Aun asanachotsedwe komanso atachotsa cC8═OOH ndi Pph3.Kuti titsanzire bwino zomwe zidachitika kale, tidagwiritsa ntchito njira cC8═OOH-50 posakaniza cC8═OOH ndi cC8═ kuti zotsatira zilizonse za cC8═ zotulutsa epoxidation zipangidwenso.Zotsatira zinasonyeza kuti pamaso pa cC8═OOH-50, EB inachita bwino (Mkuyu 2, curve 4).Komabe, ngati cC8═OOH idachotsedwa ndi Pph3, panalibe chochita pa ola loyamba ndikupondereza ntchito pambuyo pake (curve 5).Deta iyi idathandiziranso chitsanzo chakuti gawo lothandizira la Aun linali kupanga cC8═OOH mosalekeza kudzera pa cC8═ oxidation, ndipo cC8═OOH idayambitsa EB reaction.Ntchito yothandiza ya Aun idatsimikiziridwanso powona kuti milingo yoyambirira ya okosijeni wa EB pakalibe cC8═OOH idakwera ndikuwonjezeka kwa Aun (mkuyu S3).

Udindo wapadera wa Aun mu NCCS iyi udawonetsedwa powunika Co ngati chothandizira china, chomwe chidasankhidwa chifukwa cobalt acetate ndi cobalt cycloalkanecarboxylate (13) ndizomwe zimapangitsa kuti EB isinthe kukhala acetophenone yokhala ndi molekyulu O2, yomwe imagwira ntchito movutikira ndipo imafunikira kukhalapo kwa ayoni acid ndi bromide.Co complexes amagwiritsidwanso ntchito posankha aerobic EB oxidation pamaso pa organocatalyst N-hydroxyphthalimide (NHPI) kapena nsembe yochepetsera (14, 15).Komabe, malinga ndi momwe timachitira, kukhalapo kwa Co/ZSM-5 sikunapangitse kuti makutidwe ndi okosijeni a EB, cC8═ adziwike, kapena kusakaniza kwawo kwa maola 6.Ndiko kuti, Co yekha sakanatha kuyambitsa ma oxidation reaction.Komabe, pamaso pa onse a Aun ndi cC8═, zidathandizira kachitidwe ka okosijeni.Kutengera momwe zinthu ziliri, cC8═ kapena EB idachita mwachangu katatu kapena kasanu pomwe Co/ZSM-5 idapezeka, ndipo kuwongolera kudakula ndi kuchuluka kwa Co/ZSM-5 (tebulo S2, kuyesa 6 mpaka 8).Kugawa kwazinthu za EB oxidation kunasinthanso pang'ono pamaso pa Co/ZSM-5.Kuchulukitsa kuchuluka kwa Co/ZSM-5 kunachulukitsa zokolola za acetophenone ndipo, pang'ono, zokolola za phenylethanol mowononga EB hydroperoxide (tebulo S3, kuyesa 6 mpaka 8), mogwirizana ndi zomwe Co catalyzed kuwonongeka kwa EB hydroperoxide acetophenone ndi phenylethanol ndi makutidwe ndi okosijeni omaliza kukhala acetophenone.Kuti tichite bwino, tidaphatikiza Co/ZSM-5 pakusakaniza kwathu kuti tifupikitse nthawi yochitira.

Chinthu chosiyanitsa pakati pa NCCS ndi machitidwe a tandem ndi chakuti kale, palibe mgwirizano wa stoichiometric pakati pa zochita A ndi B (mkuyu 1).Kuti titsimikizire kuti zomwe tidachitazo zidachitika kudzera mu NCCS, tidayesa kusintha kwa chiŵerengero cha cC8═ kukhala EB powunika momwe amachitira.Chithunzi 3 chikuwonetsa zotsatira zakusintha koyambira kwa cC8═ ndikusunga ndende yoyambira ya EB ndi zina zomwe zimachitika nthawi zonse.Deta ikuwonetsa kuti panalibe mgwirizano wokhazikika wa stoichiometric pakati pa kuchuluka kwa ma reactants awiriwo adachita, kutsimikizira kuti machitidwewa amasiyana ndi dongosolo lachikhalidwe la tandem reaction.Kuyesa kofananira komwe kuyika koyambirira kwa EB kunali kosiyanasiyana pomwe kukonza zowunikira zina kunafika pamapeto omwewo.Kuchokera pazidziwitso izi, miyeso yoyambira idawerengedwa (Table 1 ndi tebulo S2, zoyeserera 4 ndi 5) ndikuwonetsedwa kuti zimasiyana mosiyanasiyana kwa cC8═ ndi EB.Panalibe kusinthana kwa kachitidwe pakati pa machitidwe awiriwa kotero kuti pamene chochita china chinkapita mofulumira, chinacho chimayenera kukhala chochepa kwambiri.Ziwerengero zonse ziwirizi zitha kukwera nthawi imodzi, monga zikuwonetsedwa ndi kuyesa 4 ndi 5 patebulo S2.Kusinthanitsa kungayembekezeredwe ngati EB ndi cC8═ apikisana pa malo omwewo omwe amachitirapo kanthu kapena apakatikati.Izi zikugwirizananso ndi mfundo yakuti machitidwe a nthawi imodzi a EB ndi cC8═ analibe kapena zotsatira zochepa kwambiri pa kugawa kwawo kwa mankhwala, monga momwe tawonetsera mu Table 1 ndi table S3.

Zoyambira za cC8═ zinali 0.34 M (A), 1.05 M (B), ndi 1.75 M (C).Decane idagwiritsidwa ntchito kupanga kusiyana kwa kuchuluka kwa cC8═ yogwiritsidwa ntchito.Zinthu zina: 32 mg wa Co/ZSM5, 100°C.

Deta iyi ikugwirizana ndi ndondomeko yamakina yomwe ikuwonetsedwa mu Chithunzi 4, momwe masitepe ofunikira a NCCS akugogomezera ndipo ochita masewerawa amasonyezedwa (chiwembu chokwanira chikuwonetsedwa mkuyu. S8).Mu makina awa, magulu a Aun amayambitsa cC8═ epoxidation cycle popanga cyclooctenyl radicals (I) ndi cyclooctene peroxy radicals (II).Ma radicals awiriwa amatenga nawo gawo mu cC8═ epoxidation cycle, monga zidakhazikitsidwa kale (2, 16).EB ikakhalapo, II imakhala molekyu wapakati ndikutseka pakati pa cC8═ epoxidation cycle ndi EB oxidation cycle.Mu EB cycle, II amakumana ndi EB kupanga phenylethyl radical, yomwe nthawi yomweyo imapanga phenylethyl peroxy radical (III) pochita ndi O2, monga carbon-centered radical reactions with O2 imadziwika kuti ndiyosavuta kwambiri (1).Kutulutsa kwa hydrogen kotsatira ndi III kumapanga phenylethyl hydroperoxide ndipo pamapeto pake acetophenone ndi phenylethanol.III imathanso kuchitapo kanthu mwachangu ndi cC8═, yomwe imakhala njira yobwezeretsanso II yomwe imadyedwa ndi EB oxidation cycle.Chifukwa chake, EB oxidation reaction siyimatsagana ndi kuponderezedwa kwa stoichiometric kwa cC8═ epoxidation reaction, ndipo palibe "malonda" pamayendedwe a EB ndi cC8═ momwe zingayembekezeredwe ngati atapikisana nawo reagent yomweyo. kapena tsamba lothandizira.Chifukwa II amatenga nawo gawo poyambira ma EB ndi cC8═ ma oxidation cycle koma osati mwachindunji masitepe opangira zinthu, kulumikiza kwake kuwiri sikukhudza kugawa kwazinthu.

Cyclooctene peroxy radical (II) ndiye mkhalapakati wamkulu yemwe amayambitsa EB oxidation.II ikhoza kupangidwanso ndi machitidwe a EB peroxy radical (III) ndi cC8═.Kumanzere kumanzere, magulu a Aun amayambitsa cC8═ epoxidation cycle (kuzungulira kumanzere).Kuzungulira kumanja kumawonetsa masitepe a EB oxidation.Masitepe ofunikira okha a NCCS ndi omwe akuwonetsedwa.

Kuti titsimikizire mapangidwe a intermediates osakhalitsa monga momwe tafotokozera mkuyu 4, tinawonjezera msampha wa spin 5,5-dimethyl-1-pyrroline N-oxide (DMPO) kusakaniza kosakanikirana kuti apange nthawi yayitali ya nitroxide radical spin adducts ndi ma radicals aulere omwe amapezeka kuti azindikire ndi X-band electron paramagnetic resonance (EPR) spectroscopy.Monga ulamuliro, palibe ma radicals omwe adagwidwa ndi DMPO mu njira yothetsera acetone ndi decane popanda C8═ kapena EB (mkuyu S4-3).Pamene DMPO idawonjezedwa ku kaphatikizidwe kamene kamakhala ndi cC8═OOH ndi cC8═ (mkuyu S4-1), mawonekedwe a EPR omwe adatsatiridwawo adafanizidwa bwino ngati kuchuluka kwa mitundu yayikulu yosiyana ya paramagnetic (A pachithunzichi, ~86% yonse kayeseleledwe kwambiri) ndi mitundu iwiri yaing'ono (B ndi C, ~ 5 ndi ~ 9% ya mphamvu zonse zofananira, motsatana), zomwe zimapereka umboni wachindunji wa mapangidwe opitilira muyeso panthawiyi.Pamaziko a kuyerekeza kwa ma hyperfine coupling values ​​kwa omwe amadziwika kuti DMPO adducts (tebulo S1), mitundu C idaperekedwa kwa DMPO/ROO• adduct, mwachiwonekere cyclooctene 3-peroxy radical (II) yowonetsedwa ngati mkhalapakati pakati pa ziwirizi. zochita (mkuyu. 4).Mitundu A ndi B inaperekedwa ku mitundu iwiri yosiyana pang'ono ya DMPO/RO•, pamene R ankanena za hydrocarbon moiety.Atha kukhala amodzi mwa mitundu ya RO• yomwe yafotokozedwa mu Fig. 4 kapena alkoxy radicals opangidwa kuchokera ku DMPO/ROO• adduct decay [DMPO/ROO• adducts amadziwika kuti ndi osakhazikika komanso amawola molingana ndi alkoxy radical adduct (17, 18)] kapena osakaniza onse awiri.Pamene EB inaphatikizidwanso m'kusakaniza kosakanikirana, zotsatira zake za EPR zinafaniziridwa bwino ndi mitundu yambiri ya A′, yomwe inali yofanana kwambiri ndi mitundu ya A (DMPO/RO•), ndi mitundu iwiri yaing'ono ya B ndi C yokhala ndi zopereka zazing'ono zofanana. (mkuyu S4-2 ndi tebulo S1).Chifukwa kuphatikizidwa kwa EB kunkayembekezeredwa kuyendetsa mapangidwe a phenylethyl peroxy radicals (III), mitundu ya A′ mwina inali yosakanikirana ndi RO• yopangidwa muzochita komanso phenylethyl peroxy adduct, yomwe pambuyo pake inavunda ku phenylethyl oxy DMPO adduct.

Kugwiritsa ntchito EB-d10 ngati reactant ndikuyang'anira zolemba za deuterium m'zinthu za cC8═ zitha kudziwa ngati pali kukhudzidwa kwa EB ndi cC8═ based carbon radicals.Zotsatira za kuyesera koteroko zinasonyeza kuti panalibe deuterium incorporation mu cyclooctene epoxide (mkuyu. S5 ndi S6).Phenylethanol adasunga zonse za deuterium mu EB reactant, ndipo ena mwa ma deuterons mu gulu la methyl la acetophenone adasinthanitsa, zomwe zitha kuchitika mu spectrometer yayikulu.Chifukwa chake, panalibe umboni wochitapo kanthu pakati pa EB-d10 ndi cyclooctenyl radical, yomwe ingayambitse deuteron muzinthu za cC8═.

Kugwiritsa ntchito njira ya NCCS kunakulitsidwa kuti muwone Au + cC8═OOH-100-assisted aerobic oxidation ya 4-methylanisole.Chifukwa cha zomangira zamphamvu za C─H mu molekyulu iyi, machitidwe a oxy-functionalization adachitika pa kutentha kwakukulu.Miyezo yoyamba ya kutembenuka kwa 4-methylanisole ku 4-anisaldehyde inafaniziridwa ndi machitidwe omwe anayambika ndi Aun ndipo mwina kapena opanda cC8═ kuwonjezera (cC8═OOH inachotsedwa ndi Pph3).Mofanana ndi EB makutidwe ndi okosijeni, pamene anachita osakaniza munalibe cC8═ ndipo palibe cC8═OOH, koyamba makutidwe ndi okosijeni mlingo anali pang'onopang'ono (mkuyu. S7).Pamene cC8═ idawonjezedwa pazosakaniza zomwe zimachitika, kuchuluka kwa okosijeni koyambirira kudakulirakulira.Choncho, magulu a Aun adatha kupanga cC8═OOH kuchokera ku cC8═ yowonjezera kuti ayambe oxidation ya 4-methylanisole monga momwe amayembekezera ku NCCS.

Pomaliza, tawonetsa lingaliro la NCCS.Pogwiritsa ntchito oxidation munthawi yomweyo ya cyclooctene ndi EB komanso cyclooctene ndi 4-methylanisole, NCCS idawonetsedwa kuti imathandizira kuphatikizika kwa ma hydrocarboni popanda zopinga za ubale wa stoichiometric wa njira zachikhalidwe zakuphatikizana.Izi zimapereka digiri yaufulu yomwe sinapezekepo m'ntchito zamafakitale kotero kuti ndondomeko zachuma sizikugwirizananso ndi kufunikira kwa misika yabwino yazinthu zopangidwa ndi stoichiometric.

Magwero ndi chiyero cha mankhwala ogwiritsidwa ntchito anali motere: HAuCl4•3H2O (≥99.9% trace zitsulo maziko, Sigma-Aldrich), fumed silica (CAB-O-SIL90, Cabot Corporation), ethylenediamine (≥99% ReagentPlus, Sigma-Aldrich) , ethanol (200 kalasi, Decon Labs), cobalt(II) nitrate hexahydrate (≥98%, Sigma-Aldrich), Nano H-ZSM-5 (P-26, ACS Material), decane (≥99% ReagentPlus, 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), hydrogen peroxide (30% aqueous solution, Fisher Chemical), potaziyamu hydroxide (reagent grade, 90%, Sigma-Aldrich), sodium sulfate (Food Chemicals Codex/United States Pharmacopeia–grade, Fisher Chemical), tetrahydrofuran (>99%, Sigma-Aldrich), tert-butyl hydroperoxide (~5.5 M mu decane) , Sigma-Aldrich), PPh3 (> 98.5%, Sigma-Aldrich), d-chloroform (99.8 atomic % D, Sigma-Aldrich), HCl (38% w/w, Fisher Chemical), HNO3 (68 mpaka 70% w /w, Fisher Chemical), EM Quant peroxide test strips, ndi syringe fyuluta (polyvinylidene difluoride membrane, 0.25 mm / 0.2 μm, Acrodisc).

Au/SiO2.Chothandizira chagolide chothandizidwa ndi silika cha nanoparticle chinakonzedwa ndi Au (en) 2Cl3 kalambulabwalo molingana ndi njira yopangidwa ndi Zhu et al.(19) ndi kusinthidwa ndi Qian et al.(2).Kuti mudziwe zambiri, njira ya Au(III) chloride trihydrate inakonzedwa mwa kusungunula 0,5 g ya HAuCl4 • 3H2O mu osakaniza omwe ali ndi 10 ml ya ethanol ndi 2 ml ya madzi.Pambuyo popanga njira yothetsera homogeneous, 0,23 ml ya ethylenediamine (en = ethylenediamine) inawonjezeredwa ku yankho la dropwise kupanga Au(III) ethylenediamine chloride [Au(en)2Cl3] ndi ligand exchange.As-formed Au(en)2Cl3 adasonkhanitsidwa ndikusefera ndikutsukidwa ndi 300 ml ya ethanol.Kuyika Au ku chithandizo cha silika, yankho lamadzi la 4.2 mM Au(en)2Cl3 linakonzedwa posungunula 46.3 mg wa Au(en)2Cl3 mu 26 ml ya madzi osungunuka (DDI).Njira yothetsera as-formed imasungidwa pa 40 ° C posamba mafuta.Kenako, 1 g wa fumed silika anawonjezedwa kwa preheated njira pamene oyambitsa.Zothandizira zonse za silika zitamizidwa mumtsuko, zosakanizazo zimachotsedwa mumadzi osambira amafuta ndikuzizizira mpaka kutentha.Posintha pH ya osakaniza kukhala 9 ndikuwonjezera dontho la 0.75 M en amadzimadzi, kutsatsa kwabwinoko kwa ma cationic golide pamalo omwe ali ndi vuto loyipa kudatheka.Pambuyo poyambitsa kwa maola awiri kutentha, kusakaniza kumasefedwa ndikutsukidwa ndi 500 ml ya madzi a DDI.Kuchotsa zotsalira zosafunikira (Cl, en, zonyansa zina), keke yosefera idamwazanso mu 200 ml ya madzi a DDI pa 40 ° C.Pomaliza, Au/SiO2 yopangidwa ngati yopangidwa idasonkhanitsidwa ndikusefera ndikutsukidwa ndi madzi ena a 500 ml ya DDI ndikuwumitsa mumlengalenga usiku wonse.Kuwerengetsera kwa silika wothandizira golide nanoparticles chothandizira kunachitika mu U-chubu pansi pa O2 / O3 otaya (~ 300 ml / min) ndi ramping mlingo wa 0.12 ° C/mphindi mpaka 150 ° C.Chothandiziracho chimasungidwa mumdima pa 5 ° C.Kutsegula kwa golide, monga momwe kuwerengedwera ndi plasma optical emission spectrometry yophatikizika, inali 1.2 kulemera% (wt%), ndipo pafupifupi tinthu tating'ono tagolide toyesedwa ndi scanning transmission electron microscopy (STEM) inali pafupifupi 2 nm.

Chithunzi cha ZSM-5.Nano H-ZSM-5 anali calcined mu U-chubu pansi O2 / O3 otaya (~ 300 ml / min) ndi ramping mlingo wa 2 ° C / mphindi mpaka 200 ° C ndi unachitikira 200 ° C kwa ola 1 kuchotsa. zotsalira zidindo.Co/ZSM-5 idakonzedwa ndi incipient wetness.Mwachitsanzo, 5 wt % loading Co/ZSM-5 inakonzedwa powonjezera 0.72 M cobalt (II) nitrate solution [250 mg ya cobalt(II) nitrate hexahydrate mu 1.2 ml ya madzi a DDI] ku 1 g ya nano H- ZSM-5 ndikuzungulira mosamala beaker.The slurry anauma pansi pa nyali, ndipo yunifolomu pinki ufa anapangidwa.Ufa wopangidwa ngati wopangidwawo udakwezedwa mu chubu chowongoka ndikutsukidwa pansi pa argon flow (100 ml / min) kwa ola la 1 kuti muchepetse chinyezi.Chothandizira chokonzekera chinasinthidwa pansi pa kutuluka kwa okosijeni (60 ml / min) ndi kuthamanga kwa 10 ° C / min mpaka 450 ° (kusungidwa pa 250 ° C, 350 ° C, ndi 450 ° C kwa ola limodzi lililonse) .Co/ZSM-5 yomwe yapezedwa ili ndi kutsitsa kwa cobalt kwa 5 wt%.Zida zina ziwiri, 3 ndi 7 wt%, zidakonzedwanso.Zothandizira zonse zitatuzi zinkadziwika ndi kuchepetsa kutentha kwa pulogalamu ya H2, x-ray diffraction, x-ray photoelectron spectroscopy, ndi ultraviolet-spektroscopy.

Sefa yokhala ndi Au-containing.The Au-containing filtrate (Au + cC8═OOH-x) inali in situ yopangidwa kuchokera ku Au/SiO2-catalyzed cC8═ epoxidation reaction molingana ndi njira yopangidwa ndi Qian et al.(2) Asanachitepo kanthu, cC8═ idayeretsedwa kuti ichotse chokhazikika chowonjezera cha wopanga.Nthawi zambiri, 50 ml ya 3 M potaziyamu hydroxide (KOH) yankho adawonjezeredwa ku 50 ml ya cC8═ mu botolo.Pambuyo pa kusakaniza kokwanira ndi kusonkhezera mwamphamvu, organic wosanjikiza anasonkhanitsidwa ndi kupatukana.Njirayi idabwerezedwanso ndi 50 ml ina ya 3 M KOH ndi ena awiri 50 ml ya madzi a DDI.CC8═ idawumitsidwa ndi sodium sulfate usiku wonse.Kuti achotseretu stabilizer, cC8═ yowuma idasungunuka mu mafuta osamba pafupifupi 180 ° C, ndipo kachigawo kamene kanatuluka pa 145 ° C chinasonkhanitsidwa.Oyeretsedwa cC8═ (10 ml) ndi decane (1 ml) adasakanizidwa mu riyakitala yokhala ndi 80 mg ya chothandizira chomwe chatchulidwa pamwambapa cha Au/SiO2.The cC8═ epoxidation reaction inkachitika pansi pa mpweya wotuluka (30 ml / min) pa 100 ° C, ndipo kutembenuka kunayang'aniridwa ndi GC.Pamene ankafuna kutembenuka anafika, zimene osakaniza anasonkhanitsidwa ndi chothandizira olimba anachotsedwa ndi otentha kusefera ntchito syringe fyuluta.Mlingo wa solubilized wa Au womwe udatsimikiziridwa ndi plasma mass spectrometry yophatikizika kwambiri inali pafupifupi 80 ng/ml, ndipo kukula kwa gulu la Au kunatsimikiziridwa ndi ma fluorescence spectroscopy ndi ma aberration-corrected transmission electron microscopy kuyambira Automu mpaka ~0.7 nm.cC8═OOH-x idakonzedwa chimodzimodzi popanda kugwiritsa ntchito chothandizira cha Au/SiO2.Mayankho onse a Au + cC8═OOH-x ndi cC8═OOH-x anali ndi cC8═ oxidation zinthu, zomwe zimaphatikizapo cyclooctene oxide, cyclooctene 3-hydroperoxide, 2-cycloocten-1-ol, 2-cycloocten-1-imodzi, ndi kufufuza 1,2-cyclooctanediol.

General ndondomeko.EB oxidation reactions inkachitika mumdima mu riyakitala ya makosi atatu ya cylindrical yokhala ndi chubu chabwino cha frit glass disperser chubu (Chemglass Life Sciences) ndi condenser yosungidwa pa −10°C.Monga momwe zimakhalira, 7 ml ya EB, 1 ml ya decane, ndi 3 ml ya kusefera (Au + cC8═OOH-x kapena cC8═OOH-x) adakwezedwa mu riyakitala pamodzi ndi cholumikizira cha maginito cha Teflon.Ngati atagwiritsidwa ntchito, 32 mg ya 5% Co/ZSM-5, pokhapokha atanenedwa mwanjira ina, adawonjezedwa.Pambuyo pokonzekera zomwe zidasonkhanitsidwa, zosakanizazo zidakhazikika pansi pakuyenda kwa N2 kwa mphindi 20 mubafa lotenthetsera mafuta.Pamene kutentha kwa condenser ndi kusamba kwa mafuta kunakhazikika, kuyenda kosalekeza kwa O2 kunaperekedwa pa 30 ml / min.The osakaniza anachita (0.1 ml) anatengedwa pa intervals osiyana nthawi kusanthula (syringe fyuluta ntchito pamene chothandizira olimba anali nawo), kusungunuka mu 0,7 ml ya d-chloroform, ndi kusanthula ndi 1H nyukiliya maginito resonance (NMR).

Kuzindikiritsa katundu ndi quantification.Aliquots of the reaction osakaniza adachepetsedwa ndi tetrahydrofuran ndikuwunikidwa ndi gas chromatography–mass spectrometry (GC-MS; Agilent GC-7890A, MS-5975).Pamachitidwe a EB, acetophenone ndi 1-phenylethanol adadziwika kuti ndizomwe zidadziwika kwambiri.1H-NMR ndi 13C-NMR (400 MHz Agilent DD2-MR400 system) adagwiritsidwa ntchito kuti atsimikizire kuti malondawo ndi ndani.1-Phenylethyl hydroperoxide, yomwe sinazindikiridwe ndi GC-MS chifukwa cha kusakhazikika kwake kwa kutentha, inadziwika ndi NMR kukhala chinthu china chachikulu.Zogulitsa zonse zitatu zinayesedwa ndi 1H-NMR pogwiritsa ntchito decane monga muyezo wamkati (mkuyu S1).Kutayika kwa evaporative kunatsimikiziridwa mosiyana ndikugwiritsidwa ntchito kukonza kuchuluka kwazinthu.Pambuyo pokonza zotayika za evaporative, palibe kusalinganika kwa kaboni komwe kunawonedwa pakuchita kwa EB.Kwa cyclooctene reaction, cyclooctene oxide, cyclooctane-1,2-diol, 2-cycloocten-1-ol, ndi 2-cycloocten-1-imodzi adawerengedwa ndi GC.Cyclooctene 3-hydroperoxide sinali yokhazikika ndipo idawonongeka mugawo la GC ndipo chifukwa chake sichinazindikiridwe.Panali pafupifupi 10% kutaya mpweya pa kutembenuka kwathunthu ngakhale atatha kubweza kutaya kwa evaporative, zomwe zitha kufotokozedwa ndi mapangidwe ang'onoang'ono azinthu zosadziwika bwino za okosijeni.

Kutembenuka ndi kusankha kusankha.Chiyerekezo cha GC kapena NMR cha molekyulu yachiwongola dzanja ku decane yamkati idagwiritsidwa ntchito kuwerengera kutembenuka ndi kusankha.Ngakhale condenser yozizira idagwiritsidwa ntchito, kunali kofunikira kubwezera kutaya kwa mpweya chifukwa cha kutentha kwambiri komanso nthawi yayitali.Ma curve owongolera ma evaporative adapezedwa pa onse EB ndi cC8═ pansi pa nayitrogeni woyenda ndikusinthidwa kukhala chiŵerengero cha EB/decane kapena cC8═/decane.Chifukwa EB ndi cC8═ ali ndi mfundo zowira zofananira, zowongolera zokhazikika zomwe zidapezeka zonse zinali 0.0044 (chiŵerengero chokhazikika chatsika pa ola limodzi).

Kuchuluka kwa hydroperoxide.Kuchuluka kwa hydroperoxide kunayesedwa ndi njira ziwiri za titration:

1) Triphenylphosphine (PPh3) titration.Ph3 (0.1 M mu EB) idagwiritsidwa ntchito kutsitsa zitsanzo zosadziwika za hydroperoxide, ndipo mapeto ake adadziwika ndi EM Quant peroxide test strip.31P-NMR idagwiritsidwa ntchito kutsimikizira kuchotsedwa kwathunthu kwa mitundu ya hydroperoxide.

2) Chizindikiro cha Iodometric.Chitsanzo (0.2 ml) chinasakanizidwa pamodzi ndi 1 ml ya CHCl3 / acetic acid (v / v = 1: 2) ndi 6 ml ya 1 M KI yankho.The osakaniza analimbikitsa mu mdima kwa 2 hours ndiyeno titrated ndi 0,005 M Na2S2O3 pamaso pa madontho ochepa wowuma njira.Pamapeto pake anafika pamene osakaniza anakhala opanda mtundu.

Njira zonsezi zinali zogwirizana mkati;komabe, zotsatira zawo zidasiyana ndi 5 mpaka 10%.Chifukwa ma Au + cC8═OOH-x ndi cC8═OOH-x omwe amagwiritsidwa ntchito pulojekitiyi adapangidwa kudzera mu cC8═OOH-initiated oxidation, kuchuluka kwa hydroperoxide kunali kosiyana ndi batch koma nthawi zonse kumakhala pakati pa 0.2 mpaka 0.5 M pokonzekera mwatsopano. cC8═OOH-40 mpaka cC8═OOH-100 zitsanzo.Kuchuluka kwa hydroperoxide kunatsika pang'onopang'ono ndi nthawi yosungira.

Zoyeserera za EPR spin msampha.DMPO (23 μl) inawonjezedwa ku 1 ml ya chitsanzo kuti ifike ku DMPO ndende ya 0.2 M, ndipo 20 mg ya Co/ZSM-5 inawonjezeredwa kusakaniza kwachitsanzo mu chubu choyesera.The osakaniza anali sonicated kwa mphindi 1 kuyimitsa chothandizira, ndipo kenako Kutentha pa 60 ° C kwa ~ 10 min.Aliquot ya osakaniza anasamutsidwa mu kuzungulira borosilicate chubing capillary chubu (1.50 m'mimba mwake × 1.80 kunja awiri, Wale Apparatus), amene anali losindikizidwa pa mapeto amodzi-chubu ichi kenako anaikidwa Wilmad quartz X-band EPR chubu. Sigma-Aldrich).Chitsanzocho chinawumitsidwa ndi kumizidwa kwa chubu cha EPR mu madzi a N2.Atangoyeza mawonekedwe a EPR, chitsanzocho chinasungunuka.Miyezo ya Continuous-wave (CW) X-band EPR idachitidwa kutentha kwa chipinda pa spectrometer yosinthidwa ya Varian E-4 pogwiritsa ntchito chala cha Dewar.

Kuyesa kwa zilembo za Isotopic.Deuterated EB (d10-EB) idagwiritsidwa ntchito poyesa kusakaniza kwa 6 ml ya cC8═OOH-45, 5 ml ya d10-EB, 1 ml ya decane, ndi 60 mg ya Co-ZSM-5 (7%). , pa 120 ° C, ndi 6 ml ya cC8═OOH-45, 5 ml ya EB-d10, ndi 1 ml ya dodecane.Kubwezera kuchepa kwa kachitidwe chifukwa cha kinetic isotope athari, co-oxidation idachitika pa kutentha kwakukulu kwa 120 ° C.Ma Aliquots a zitsanzo adatengedwa kusanachitike komanso pambuyo pa maola 24 akuyankha ndikuwunikidwa ndi 2H-NMR ndi GC-MS.

Sipekitiramu ya 2H-NMR (mkuyu S5, sipekitiramu 2) inawonetsa nsonga zingapo zatsopano pambuyo pochita, zomwe sizinachitikepo musanachitepo kanthu, pa δ1.50, δ1.58, δ4.94, δ7.42 mpaka δ7.72, ndi δ8.04 .Chifukwa cha kuchepa kwa J-coupling mosalekeza komanso kumva kwa 2H-NMR, njira zogawanika sizinathe.Pamwamba pa δ8.04 ndi δ7.42 mpaka δ7.72 anaperekedwa kwa ma deuterons a mphete yonunkhira ya acetophenone;nsonga za δ1.50 ndi δ4.94 zinaperekedwa ku methyl ndi benzylic deuteron ya 1-phenylethanol, motsatira;ndipo pachimake pa δ1.58 adatumizidwa ku deuteron mu D2O yopangidwa kuchokera ku kuwonongeka kwa hydroperoxide.Palibe deuteron yomwe idapezeka yolumikizidwa ndi zinthu za cyclooctene epoxidation, ndipo mapangidwe amadzi opumira adawonetsa kuti zonyamulira zazikulu zamaketani mu co-oxidation reaction anali peroxy ndi alkoxy based.

Mawonekedwe a GC-MS azinthu akuwonetsedwa mkuyu.S6.Acetophenone-d8 (m/e 128, deuterated kwathunthu, mkuyu S6A, m/e 127 ndi 126) anawonedwa.Kuchokera pamachitidwe osweka, kusinthana konse kwa HD kunachitika pamalo a methyl.Kuphatikiza apo, 1-phenylethanol-d9 (m/e 131) (mkuyu S6B) ndiyo yokhayo yomwe idapezeka.Palibe deuterium yomwe inapezeka mu cyclooctene oxide (mkuyu S6C), chinthu chochuluka kwambiri kuchokera ku cyclooctene epoxidation.1-Phenylethanol-d9 ikhoza kupangidwa kuchokera ku phenylethoxy radical ndi cyclooctene.

Zowonjezera za nkhaniyi zikupezeka pa http://advances.sciencemag.org/cgi/content/full/6/5/eaax6637/DC1

Chithunzi cha S5.2H-NMR isanayambe (sipekitiramu 1, yofiira) ndi pambuyo (sipekitiramu 2, yobiriwira) maola 24 a co-oxidation reaction.

Chithunzi cha S7.Kuyerekeza kwa kutembenuka koyambirira kwa 4-methyl anisole yoyambitsidwa pogwiritsa ntchito Au + cC8═OOH-100, ndi cC8═OOH yachotsedwa.

Imeneyi ndi nkhani yotseguka yoperekedwa pansi pa chilolezo cha Creative Commons Attribution-NonCommercial, chomwe chimaloleza kugwiritsa ntchito, kugawa, ndi kubereka mumtundu uliwonse, malinga ngati kugwiritsidwa ntchito kwake sikungapindule ndi malonda ndipo ngati ntchito yoyambayo ili yoyenera. otchulidwa.

ZINDIKIRANI: Timangopempha adilesi yanu ya imelo kuti munthu amene mukumupangira tsambalo adziwe kuti mumafuna kuti aliwone, komanso kuti si imelo yopanda pake.Sitijambula imelo iliyonse.

Wolemba Anyang Peng, Mayfair C. Kung, Robert RO Brydon, Matthew O. Ross, Linping Qian, Linda J. Broadbelt, Harold H. Kung

Mu makina othandizira osagwirizana, oyimira pakati ochokera ku Au-catalyzed cyclooctene epoxidation zotsatira ethylbenzene oxidation.

Wolemba Anyang Peng, Mayfair C. Kung, Robert RO Brydon, Matthew O. Ross, Linping Qian, Linda J. Broadbelt, Harold H. Kung

Mu makina othandizira osagwirizana, oyimira pakati ochokera ku Au-catalyzed cyclooctene epoxidation zotsatira ethylbenzene oxidation.

© 2020 American Association for the Advancement of Science.Maumwini onse ndi otetezedwa.AAAS ndi mnzake wa HINARI, AGORA, OARE, CHORUS, CLOCKSS, CrossRef ndi COUNTER.Science Advances ISSN 2375-2548.