Dhaqan ahaan, kicinta waxay ku shaqeysaa isdhexgalka tooska ah ee falcelinta.Nidaamka catalytic-ka cusub ee aan la xidhiidhin (NCCS), dhexdhexaad ah oo ay soo saarto hal fal-celin catalytic ah ayaa u adeegta sidii dhexdhexaadiye si ay awood ugu siiso fal-celin madax-bannaan inay sii socoto.Tusaale ahaan waa oksaydhaynta xulashada ee ethylbenzene, taas oo aan ku dhici karin joogitaanka Au nanoclusters ama cyclooctene midkood, laakiin si fudud u socday markii labaduba ay isku mar joogeen.Epoxidation-ka xulashada Au-bilabay ee cyclooctenyl waxa uu dhaliyay cyclooctenyl peroxy iyo radicals oxy kuwaas oo u adeegay dhexdhexaadin si loo bilaabo oxidation ethylbenzene.Nidaamkan la isku daray ayaa si wax ku ool ah u kordhiyay saamaynta catalytic ee Au.Habka falcelinta waxaa taageeray kinetics falcelinta iyo tijaabooyinka dabinka.NCCS waxay awood u siisaa falcelinta isbarbar-dhigga ah si ay u sii socoto iyada oo aan la helin caqabadaha cilaaqaadka stoichiometric, iyada oo bixisa heerar cusub oo xorriyadda hababka is-kaashatada hydrocarbon ee warshadaha.

Dhaqan ahaan, kicinta waxay si toos ah ula falgashaa fal-celiyeyaasha (falcelinta A) si ay u dhaqangeliso dib-u-qaabaynta curaarta ee uu fal-celintu qoray.Tusaale ahaan, oksaydhka cobalt-catalyzed ee alkylaromatics (1) ama Epoxidation-ka Au-catalyzed ee cyclooctene (2), kicinta ayaa fududaysa soo saarista atamka hydrogen ka hydrocarbon si uu u bilaabo falcelinta.Dareen-celinta silsiladda xagjirka ah ee xorta ah, kiciyahu waxa uu ka qaybqaataa kala-goynta homolytic-ka ee curaarta daciifka ah ee bilawyaasha kuwaas oo si ula kac ah loogu daray ama u jooga sida wasakhda adventitious ee isku dhafka falcelinta (1, 3, 4).Tallaabooyinka qaar ee falcelinta tandem katalytic uma baahna xiriir toos ah substrate-katalyst marka beddelka substrate-ka uu karti u yeesho badeecad si firfircoon loo soo saaray tillaabooyinka hore (5-8).Si kastaba ha ahaatee, falcelintan waxaa xaddiday xiriirka stoichiometric ee u dhexeeya tallaabooyinka.Tusaale ahaan, Mukaiyama (ep) oksaydhaynta alkene, kataliyuhu waxa uu beddelaa dhimis allabaryo fal-celin A, sida isobutyraldehyde, oo leh isku-xidhka istichiometric formation of epoxide (falcelinta B) (9, 10).Inkasta oo ay suurtogal tahay mabda'a ahaan, ma nihin tusaale ahaan taas oo shaqada kicinaysa ay tahay in ay soo saarto dhexdhexaad ah S ee falcelinta A, halkaas oo S u adeegto dhexdhexaad si ay u bilawdo ama u kiciso falcelin kale B halkii ay ka qayb qaadan lahayd reagent stoichiometric. , halka kataliyuhu aanu waxtar u lahayn falcelinta B (Jaantus. 1).Nidaamkan oo kale, saamaynta kiciyahu waxa lagu kordhiyaa wax ka bedelka falcelinta A ilaa saamaynaysa falcelinta B laakiin aan xidhiidh toos ah la lahayn fal-celinteeda.Waxa aanu ku macnaynaynaa nidaamkan nidaam katalytik ah oo aan xidhiidh la lahayn (NCCS).NCCS gudaheeda, xadka falcelinta falcelinta A iyo B kuma xidhna xidhiidh kasta oo stoichiometric ka dhexeeya.Tani waxay ka duwan tahay falcelinta tandem.Warshadaha, xidhiidhka stoichiometric ee noocan oo kale ah wuxuu inta badan ku soo rogaa caqabado dhaqaale habka wax soo saarka kiimikada.Tusaalaha si fiican loo yaqaan ayaa ah wax soo saarka stoichiometric ee phenol iyo acetone by oksaydhka benzene iyada oo loo marayo dhexdhexaadiyaha cumene hydroperoxide ee habka cumene (11).

Katalysator (Bisad) ayaa kicisa falcelinta A (AR ➔ S ➔AP) kaas oo dhexdhexaadka S uu waxtar u leeyahay kicinta ama kicinta falcelinta B (BR ➔ BP), inkasta oo falcelinta B aanay kicin kicinta.

Waxaan helnay sida NCCS markii la sahamiyay sifooyinka firfircoonida ee rucubyada Aun milmay (halkaasoo n inta badan ahaa lix ilaa siddeed atamka) ee qayb ahaan oksaydheynta ethylbenzene (EB).Waxaan soo bandhignay in kuwan la milmay Aun ay kicisay bilawga epoxidation xulashada ee cycloocene (cC8═) oo leh O2 leh ~ 80% xulashada (2).Kooxahan waxaa lagu sameeyay goobta inta lagu gudajiray Au/SiO2-catalyzed cC8═ epoxidation, waxayna sii wadeen awooda ay u leeyihiin in ay dhaliyaan cycloocctene hydroperoxy radical (cC8═OO ·) intii ay falcelinta socotay.Kooxaha Aun ee la milmay waxa lagu soo ururin karaa isku darka falcelinta ka dib markii laga saaray Au/SiO2, waxaana cabbirkooda celcelis ahaan lagu go'aamiyay iyada oo la isticmaalayo mikroskoobyada elektarooniga ah ee la saxay iyo spectroscopy fluorescence (2).Marka lagu daro kooxaha Aun, isku dhafkan ayaa sidoo kale ka koobnaa cyclooctene hydroperoxide (cC8═OOH) iyo alaabada oksaydhka ee cyclooctene epoxide, cyclooctenol, iyo cyclooctenone.cC8═OOH waxa uu ahaa qaabka hydrogenated ee cC8═OO· oo deggan 0.2 ilaa 0.5 M ka dib 40 ilaa 100% cC8═ beddelidda.Isku dhafkan waxaa loo tixraacaa sida Au + cC8═OOH-x, halkaasoo x ay tahay boqolkiiba cC8═ beddelka.In kasta oo heer aad u gaabis ah oo dheer (> 5 saacadood) muddada soo-gelinta, cC8═ epoxidation waxay sidoo kale ku dhici kartaa auto-oxidation iyada oo aan la helin kooxaha Aun.Isku darka ay heleen auto-oxidation oo aan lahayn Au waxa loo yaqaan cC8═OOH-x.Gudaha NCCS, Aun-ka la milmay ayaa noqon doona kicinta, epioxidation ee cC8═ waxay noqon doontaa falcelin A, iyo cC8═OO waxay noqon doontaa S.

Auto-oxidation ee EB si sahal ah uma dhacdo.Marka la joogo 145°C, kaliya 9% falcelin ayaa ku dhacay EB nadiif ah oo ka hooseeya 2.76 MPa O2 (12).Marka loo eego xaaladahayada aadka u fudud ee 100°C iyo O2 oo bubbaysa 0.1 MPa, ma jirin falcelin la ogaan karo oo ah EB nadiif ah ugu yaraan 20 saacadood.Ku darida bilawga xagjirka xorta ah ayaa loo baahnaa si falcelintani u socoto.Bilawga 2,2'-azobisisobutyronitrile (AIBN), oo ah bilawga xamaasada kulaylka aadka u firfircoon, waxay keentay auto-oxidation ee EB oo leh celcelis ahaan dhererka silsiladda ~ 3 (fig. S2A).Silsilad gaaban (~ 1) ayaa lagu arkay iyadoo la adeegsanayo tert-butyl hydroperoxide (fig. S2B), waxaana jiray falcelin aad u yar oo la ogaan karo iyadoo la adeegsanayo cumene hydroperoxide ugu yar.Sidaa darteed, auto-oxidation ee EB ayaa saameyn yar ku yeeshay natiijooyinka falcelinta ee hoos lagu sheegay.

oksaydhdheynta hawada ee joogtada ah ee EB ilaa EB hydroperoxide, acetophenone, iyo phenylethanol ayaa lagu gaadhay in lagu daro Au + cC8═OOH-50 ka kooban isku dar ah Aun, cC8═OOH, iyo cC8═ aan la falcelinin (Jaantus. 2, qalooca 1).Sida lagu muujiyay tijaabooyinka soo socda, saddexdan qaybood ayaa door muhiim ah ka ciyaaray oxidation EB, waxayna u dhigmaan kicinta, S, iyo AR ee nidaamka NCCS ee lagu sawiray shaxanka 1.

(i) 7 ml oo EB + 3 ml oo Au + cC8═OOH-50;(ii) 7 ml oo EB + 3 ml oo Au + cC8═OOH-50 + 1.2 mmol PPh3;(iii) 7 ml oo ah EB + 3 ml oo Au + cC8═OOH-99 + 0.6 mmol PPh3;(iv) 7 ml EB + 3 ml oo cC8═OOH-50;(v) 7 ml oo EB + 3 ml oo cC8═OOH-50 + 1.5 mmol PPh3.Tirada PPh3 lagu daray ayaa loo dejiyay inay la mid noqoto tirada hydroperoxide titrated (heerkulka falcelinta, 100°C).

Xaaladeena, ma jiro oksidation aerobic EB oxidation oo la arki karo oo ku dhacay isku dhafka cC8═ iyo EB (ie, iyada oo aan lahayn Bisad ama S).Triphenylphosphine (PPh3) ayaa aad waxtar u leh inay meesha ka saarto hydroperoxides.Xalka Au + cC8═OOH-99, oo laga dhammeeyay cC8═OOH oo ay ku daray PPH3, oo ka kooban Aun iyo cC8═ aad u yar oo aan falcelin lahayn, ayaa ku guul daraystay in uu bilaabo falcelinta EB xitaa 2 saacadood ka dib (Jaantus. 2, qalooca 3), taas oo muujinaysa in Aun keligiis ayaa ahaa mid aan waxtar lahayn.Natiijadani waxay sidoo kale muujisay in alaabada kale ee cC8═ oksaydhaynta, sida cyclooctene epoxide, alkolada cyclooctene, ama ketone, aysan awoodin inay bilaabaan oxidation EB.Si ka duwan tijaabada kore, ka saarista cC8═OOH oo leh PPh3 laga bilaabo Au + cC8═OOH-50, ka tagista Aun iyo cC8═ aan falcelin lahayn, kama aysan joojin beddelka EB (is barbar dhig qalooca 1 iyo 2, sawirka 2).

Saddexdan qaybood ee xogtu waxay soo jeediyeen is-dhexgal ka dhexeeya Aun iyo cC8═ aan la falgelinin ee bilawga oksaydhka EB.Waxaan qiyaasnay ​​in Aun uu kiciyay oksaydhka cC8═ si uu u sameeyo cC8═OOH, kaas oo ahaa bilawga falcelinta EB.Tan waxaa lagu tijaabin karaa marka la is barbar dhigo waxtarka bilaabista EB oxidation isku dar ah cC8═OOH iyo cC8═ laakiin aan lahayn Aun ka hor iyo ka dib saarista cC8═OOH iyo PPh3.Si aan ugu ekaysiinno xaaladaha tijaabooyinkii hore, waxaan u isticmaalnay xalka cC8═OOH-50 isku dhafka cC8═OOH iyo cC8═ si saameyn kasta oo suurtagal ah ee cC8═ alaabta epioxidation ay dib u soo saarto.Natiijooyinka waxay muujiyeen in joogitaanka cC8═OOH-50, EB ay si hufan uga jawaabtay (Jaantus. 2, qalooca 4).Si kastaba ha ahaatee, haddii cC8═OOH laga saaray PPh3, ma jirin wax falcelin ah saacaddii ugu horreysay iyo dhaqdhaqaaqa la xakameeyey ka dib (qallooca 5).Xogtaasi waxay sii taageertay tusaalaha in doorka firfircoon ee Aun uu ahaa inuu si joogto ah u dhaliyo cC8═OOH iyada oo loo marayo cC8═ oksaydhaynta, iyo cC8═OOH waxay bilawday falcelinta EB.Doorka catalytic ee Aun ayaa la sii xaqiijiyay iyadoo la eegayo in heerarka bilowga ah ee oxidation EB ee maqnaanshaha cC8═OOH ay kordheen iyada oo korodhay xoojinta Aun (fig. S3).

Doorka gaarka ah ee Aun ee NCCS-kan waxaa lagu muujiyay iyadoo la baarayo Co sida kicinta beddelka ah, kaas oo loo doortay sababtoo ah cobalt acetate iyo cobalt cycloalkanecarboxylate (13) ayaa ah kicinta warshadaha ee u beddelashada EB ilaa acetophenone leh molecular O2, oo ku shaqeeya xaalado adag oo u baahan joogitaanka aashitada iyo ion bromide.Co complexes waxa kale oo loo isticmaalaa oxidation aerobic EB oxidation joogitaanka organocatalyst N-hydroxyphthalimide (NHPI) ama dhimis allabari ah (14, 15).Si kastaba ha ahaatee, xaaladaha falcelintayada, joogitaanka Co/ZSM-5 ma keenin wax oksaydhism ah oo la ogaan karo ee EB, cC8═, ama isku darkooda ugu yaraan 6 saacadood.Taasi waa, Co kaligiis ma bilaabi karin falcelinta oksaydhka.Si kastaba ha ahaatee, iyadoo ay joogaan Aun iyo cC8═ labadaba, waxay fududaysay falcelinta oksaydhka.Iyada oo ku xidhan xaaladda, cC8═ ama EB waxay ka falceliyeen saddex ilaa shan jeer dhakhso ah markii Co/ZSM-5 uu joogay, iyo kobcinta ayaa kordhay xaddiga Co/ZSM-5 (miiska S2, tijaabooyinka 6 ilaa 8).Qaybinta sheyga oksaydhka EB ayaa sidoo kale xoogaa isbeddelay iyadoo ay joogaan Co/ZSM-5.Kordhinta qadarka Co/ZSM-5 waxay kordhisay wax-soo-saarka acetophenone iyo, ilaa xad, phenylethanol waxay soo saartaa kharashka EB hydroperoxide (miiska S3, tijaabooyinka 6 ilaa 8), oo waafaqsan xaqiiqda ah in Co catalyzed burburka EB hydroperoxide acetofenone iyo phenylethanol iyo oksaydhka dambe ee acetophenone.Faa'iidada awgeed, waxaan ku darnay Co/ZSM-5 isku darka falcelintayada si loo gaabiyo waqtiga falcelinta.

Qodobka kala sooca ee u dhexeeya NCCS iyo hababka falcelinta tandem ayaa ah in kii hore, aanu jirin xidhiidh istichiometric ah oo u dhexeeya falcelinta A iyo B (Jaantus. 1).Si loo xaqiijiyo in falcelintayadu ka dhaceen NCCS, waxaanu tijaabinay saamaynta beddelka saamiga cC8═ iyo EB annagoo la soconayna heerarkooda falcelinta shakhsi ahaaneed.Jaantuska 3 wuxuu muujinayaa natiijooyinka beddelka diirada cC8═ bilowga ah iyadoo la ilaalinayo diiradda EB-ga bilowga ah iyo xaaladaha kale ee falcelinta joogtada ah.Xogtu waxay muujinaysaa in aanu jirin xidhiidh go'an oo stoichiometric ah oo u dhexeeya tirada labada falcelis, taas oo xaqiijinaysa in qaabka falcelinta uu ka duwan yahay nidaamka falcelinta tandem ee dhaqameed.Tijaabo isku mid ah oo isku-ururinta EB-ga bilowga ah ay kala duwanaayeen iyada oo la hagaajinayo fiirsashada kale ayaa isla gunaanadkii soo gaadhay.Laga soo bilaabo xogtan, heerarka falcelinta bilawga ah ayaa la xisaabiyay (Shaxda 1 iyo miiska S2, tijaabooyinka 4 iyo 5) oo la muujiyay inay ku kala duwan yihiin cC8═ iyo EB.Ma jirin wax is beddel ah oo ku yimid heerarka falcelinta ee u dhexeeya labada falcelin sida marka mid falcelintu si degdeg ah u socoto, ka kalena uu ahaado mid gaabis ah.Labada heerar falcelintu waxay kordhin karaan isku mar, sida lagu muujiyey tijaabooyinka 4 iyo 5 ee miiska S2.Wax kala beddelasho ayaa la filayaa haddii EB iyo cC8═ ay u tartamaan isla goobta falcelinta kicinta ama dhexdhexaadka ah.Gabagabadani waxay sidoo kale la socotaa xaqiiqda ah in falcelinta isku mar ah ee EB iyo cC8═ aysan lahayn ama saameyn aad u yar ku yeelan qaybinta alaabadooda gaarka ah, sida ku cad shaxda 1 iyo miiska S3.

Xaddiga hore ee cC8═ waxay ahaayeen 0.34 M (A), 1.05 M (B), iyo 1.75 M (C).Decane waxa loo isticmaalay in lagu sameeyo kala duwanaanshaha mugga cC8═ la isticmaalay.Xaaladaha kale: 32 mg ee Co/ZSM5, 100°C.

Xogtaasi waxay la socotaa nidaamka makaanikada ee lagu muujiyey Jaantuska 4, kaas oo tillaabooyinka muhiimka u ah NCCS lagu nuuxnuuxsaday, ciyaartoyga ugu muhiimsanna la iftiimiyay (qorshe dhammaystiran ayaa lagu muujiyay sawirka S8).Habkan, kooxaha Aun waxay bilaabeen wareegga cC8═ epioxidation iyagoo soo saaraya cyclooctenyl radicals (I) iyo cyclooctenyl peroxy radicals (II).Labadan xag-jir ayaa markaa ka qaybqaata cC8═ wareegga epioxidation, sidii hore loo aasaasay (2, 16).Marka EB uu joogo, II wuxuu noqdaa unug dhexdhexaad ah iyo shuttles inta u dhaxaysa cC8═ epoxidation cycle iyo EB oxidation cycle.In wareegga EB, II falcelin la EB si ay u sameeyaan a phenylethyl radical ah, kaas oo isla markiiba sameeyo a phenylethyl peroxy radical (III) by falcelin la O2, sida kaarboon-xuddun u dareen-celinta xagjirka ah O2 la og yahay in ay aad u fudud (1).Soo saarista hydrogen ee soo socota ee III waxay sameysaa phenylethyl hydroperoxide iyo ugu dambeyntii acetophenone iyo phenylethanol.III waxa kale oo uu si degdeg ah uga falcelin karaa cC8═, kaas oo noqda dariiqa buuxinta II ee uu isticmaalo wareegga oksaydhka EB.Markaa, falcelinta oksaydhka EB kuma weheliso xakamaynta stoichiometric ee falcelinta cC8═ epoxidation, mana jirto “ganacsi-off” heerarka falcelinta EB iyo cC8═ sida la filayo haddii ay u tartami lahaayeen reagent isku mid ah. ama goobta firfircoon ee catalytic.Sababtoo ah II wuxuu ka qaybqaataa tallaabada bilawga ah ee labadaba EB iyo cC8═ wareegyada oksaydhka laakiin aan si toos ah ugu jirin tillaabooyinka samaynta sheyga, isku xidhka labada falcelin ma saamaynayso qaybinta alaabta.

Cyclooctene peroxy radical (II) waa dhexdhexaadiyaha ugu muhiimsan ee bilaabaya oksaydhka EB.II waxa lagu soo celin karaa falcelinta EB peroxy radical (III) oo leh cC8═.Dhanka bidix ee sare, kooxaha Aun waxay bilaabayaan cC8═ wareegga epioxidation (wareegga bidixda).Wareegga dhinaca midig wuxuu muujinayaa tallaabooyinka oxidation EB.Kaliya tillaabooyinka muhiimka ah ee muhiimka u ah NCCS ayaa la tusay.

Si loo xaqiijiyo samaynta dhex dhexaadinta xagjirka ah ee ku meel gaadhka ah sida lagu soo jeediyay Jaantuska 4, waxaanu ku darnay dabinka lafdhabarta ah 5,5-dimethyl-1-pyrroline N-oxide (DMPO) isku darka falcelinta si ay u sameeyaan nitroxide radical spinal radical mudda dheer Xagga xorta ah ayaa u jooga in lagu ogaado X-band eletroonig paramagnetic resonance (EPR) spectroscopy.Xakameyn ahaan, ma jiraan wax xag-jir ah oo ay DMPO ku xannibeen xal of acetone iyo decoe la'aanteed C8═ ama EB (fig. S4-3).Markii DMPO lagu daray isku darka falcelinta oo ay ku jiraan cC8═OOH iyo cC8═ (fig. S4-1), natiijada EPR spectrum si fiican ayaa loo sawiray iyadoo la isku daray noocyo kala duwan oo paramagnetic ah (A sawirka, ~ 86% wadarta guud. xoojinta jilitaanka) iyo laba nooc oo yaryar (B iyo C, ~ 5 iyo ~ 9% wadarta xoojinta jilitaanka, siday u kala horreeyaan), iyagoo siinaya caddayn toos ah samaynta xagjirka ah inta lagu jiro falcelinta.Iyada oo ku saleysan isbarbardhigga qiyamka isku-xirnaanta hyperfine iyo kuwa loo yaqaan 'DMPO adducts' (miiska S1), noocyada C waxaa loo qoondeeyay DMPO/ROO• gundhig, oo macquul ah cyclooctene 3-peroxy radical (II) oo lagu muujiyey inuu yahay dhexdhexaadiyaha u dhexeeya labada. falcelinta (Jaantus. 4).Noocyada A iyo B waxaa loo qoondeeyay laba nooc oo DMPO/RO• ah oo xoogaa kala duwan, halkaas oo R u tixraacayo unug kaarboon.Waxay noqon karaan mid ka mid ah noocyada RO• ee lagu sifeeyay sawirka 4 ama alkoxy radicals oo laga soo saaray DMPO/ROO• suuska suuska [DMPO/ROO• adducts waxaa loo yaqaanaa inay yihiin kuwo aan xasilloonayn oo u jajaban alkoxy radical adduct (17, 18)] ama labadaba isku dar ah.Marka EB sidoo kale lagu daray isku darka falcelinta, natiijada EPR spectrum si fiican ayaa loogu sawiray noocyo badan oo A′, oo aad ugu eg noocyada A (DMPO/RO•), iyo labada nooc ee laga tirada badan yahay ee B iyo C oo leh wax yar oo isku mid ah. (Jaantuska S4-2 iyo shaxda S1).Sababtoo ah ku darida EB waxaa la filayey in ay wado samaynta phenylethyl peroxy radicals (III), noocyada A' waxay u badan tahay isku dhafka RO• ee ka dhashay falcelinta iyo sidoo kale wax kasta oo phenylethyl peroxy adduct ah, kaas oo markii dambe qudhuntay phenylethyl oxy DMPO.

Isticmaalka EB-d10 falcelin ahaan iyo la socodka calaamadaynta deuterium ee alaabada cC8═ waxay ogaan kartaa in ay jirto falcelin EB ah oo leh cC8═ xaglaha carbon ku salaysan.Natiijooyinka tijaabadan oo kale waxay muujiyeen in aysan jirin isku-darka deuterium ee cyclooctene epoxide (berdaha. S5 iyo S6).Phenylethanol wuxuu hayaa dhammaan deuterium-ka falcelinta EB, iyo qaar ka mid ah deuterons ee kooxda methyl ee acetophenone ayaa isweydaarsaday, taas oo ku dhici karta spectrometer mass.Markaa, ma jirin wax caddaynaya falcelinta u dhaxaysa EB-d10 iyo cyclooctenyl radical, kaas oo soo bandhigaya deuteron galay badeecadaha cC8═.

Ku dabaqmidda istaraatiijiyadda NCCS waa la kordhiyey si loo baaro Au + cC8═OOH-100-ay caawisay oksaydhka hawada ee 4-methylanisole.Sababtoo ah curaarta aasaasiga ah ee C─H ee ku jirta molecule-kan, falcelinta oksijiinta ayaa lagu qabtay heerkul sare.Heerarka bilowga ah ee beddelka 4-methylanisole loona beddelo 4-anisaldehyde ayaa la barbardhigay fal-celinnada laga bilaabay Aun iyo midkood ama aan lagu darin cC8═ (cC8═OOH waxaa laga saaray PPh3).Si la mid ah oksaydhaynta EB, marka isku darka falcelinta aanu ku jirin cC8═ iyo cC8═OOH, heerka oksaydhka bilawga ah aad ayuu u gaabis ahaa (fig. S7).Marka cC8═ lagu darey isku darka falcelinta, heerka oksaydhka bilowga ah ayaa si muuqata loo wanaajiyey.Markaa, kooxaha Aun waxay awoodeen inay cC8═OOH ka soo saaraan cC8═ lagu daray si ay u bilaabaan oksaydhka 4-methylanisole sida laga filayo NCCS.

Gebogebadii, waxaanu soo bandhignay fikradda NCCS.Isticmaalka oksaydhka isku mar ah ee cyclooctene iyo EB iyo sidoo kale cyclooctene iyo 4-methylanisole, NCCS ayaa la muujiyay si ay u suurtageliso co-oxidation of hydrocarbons iyada oo aan xannibaadaha xiriirka stoichiometric ee hababka isku-dhafka dhaqameed.Tani waxay bixisaa shahaado xor ah oo aan horay loo heli karin oo ku saabsan dhaqanka warshadaha sida in habka dhaqaalaha uusan hadda ku xirneyn baahida loo qabo suuqyo wanaagsan oo loogu talagalay badeecadaha la midka ah ee laga soo saaro qaddarka stoichiometric.

Ilaha iyo nadiifinta kiimikooyinka la isticmaalay waxay ahaayeen sida soo socota: HAuCl4 • 3H2O (≥99.9% raadadka biraha, Sigma-Aldrich), silica fumed (CAB-O-SIL90, Shirkadda Cabot), ethylenediamine (≥99% ReagentPlus, Sigma-Aldrich) , ethanol (200 darajo, 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) . (darajada reagent, 90%, Sigma-Aldrich), sodium sulfate (Koodx kimikooyinka Cunnada/United States Pharmacopeia-grade, Kalluumeysatada Kiimikada), tetrahydrofuran (> 99%, Sigma-Aldrich), tert-butyl hydroperoxide (~ 5.5 M in decane). , Sigma-Aldrich), PPh3 (> 98.5%, Sigma-Aldrich), d-chloroform (99.8 atomic% D, Sigma-Aldrich), HCl (38% w/w, Kiimikada Fisher), HNO3 (68 ilaa 70% w / w, Kiimikada Fisher), EM Quant peroxide xariijimaha tijaabada, iyo filtarka saliingaha (xuubka polyvinylidene difluoride, 0.25 mm/0.2 μm, Acrodisc).

Au/SiO2.Qalabka dahabka nanoparticle ee silica ay taageerto waxaa lagu diyaariyay Au(en)2Cl3 horudhac iyadoo loo eegayo habka ay soo saareen Zhu et al.(19) oo ay hagaajiyeen Qian et al.(2).Si aad u noqoto mid gaar ah, Au (III) chloride trihydrate xal ayaa la diyaariyey iyadoo lagu milmay 0.5 g HAuCl4•3H2O isku dar ah oo ka kooban 10 ml ethanol iyo 2 ml oo biyo ah.Ka dib markii la sameeyay xal isku mid ah, 0.23 ml ethylenediamine (en = ethylenediamine) ayaa lagu daray xalka si loo sameeyo Au (III) ethylenediamine chloride [Au (en) 2Cl3] by ligand beddelka.Au(en)2Cl3 sida-loo sameeyay waxaa lagu soo ururiyay sifeyn waxaana lagu dhaqay 300 ml oo ethanol ah.Si AU loogu shubo taageerada silica, 4.2 mM Au(en)2Cl3 xal aqueous ah ayaa la diyaariyey iyadoo lagu milmay 46.3 mg of Au(en)2Cl3 26 ml oo ah biyo la fuuqsaday (DDI).Xalka sida loo sameeyay ayaa lagu hayaa 40 ° C ee qubeyska saliidda.Kadibna, 1 g oo ah silica qiiqa ayaa lagu daray xalka preheated marka la walaaqayo.Marka dhammaan taageerada silica lagu dhex geliyo xalka, isku dar ah ayaa laga saaray qubayska saliidda oo la qaboojiyey heerkulka qolka.Iyadoo la hagaajinayo pH ee isku dhafka ilaa 9 iyadoo lagu daray hoos u dhigista 0.75 M en xal aqueous, xayeysiis wanaagsan oo ka mid ah dhismayaasha dahabka cationic ee dusha si xun loo soo oogay ayaa la gaaray.Ka dib markii la walaaqay 2 saacadood heerkulka qolka, isku dar ah ayaa la sifeeyay oo lagu dhaqay 500 ml oo biyo ah DDI.Si meesha looga saaro hadhaaga aan la rabin (Cl, en, wasakh kale), keega shaandhada ayaa lagu kala firdhiyey 200 ml oo biyo DDI ah 40°C.Ugu dambayntii, Au/SiO2-kii sida-sameeyey waxa lagu soo ururiyey sifaynta oo lagu maydhay 500 ml oo kale oo biyo ah DDI waxaana lagu qallajiyey hawo habeenkii.Calcination of silica-taageereysa dahabka nanoparticles kataliyaha waxaa lagu sameeyay U-tube hoostiisa socodka O2/O3 (~ 300 ml/min) oo leh xadi kor u kaca ah 0.12°C/min ilaa 150°C.Daroogada waxa lagu kaydiyay mugdi 5°C.Xamuulka Dahabka ah, sida lagu qiyaaso si kadis ah oo isku xidhan balaasmaha qiiqa qiiqa, wuxuu ahaa 1.2 miisaan % (wt %), iyo celceliska cabirka walxaha dahabka ah ee lagu cabiray iskaanka gudbinta elektaroonigga ah (STEM) wuxuu ahaa ilaa 2 nm.

Co/ZSM-5.Nano H-ZSM-5 waxaa lagu shubay U-tube oo hoos timaadda socodka O2/O3 (~ 300 ml/min) oo leh xadiga kor u kaca ee 2°C/min ilaa 200°C waxaana lagu hayaa 200°C 1 saac si meesha looga saaro habyaalada haraaga ah.Co/ZSM-5 waxaa lagu diyaariyay qoyaanka bilawga ah.Tusaale ahaan, 5 wt % Co/ZSM-5 ayaa la diyaariyey iyadoo lagu daray 0.72 M kobalt (II) xal nitrate ah [250 mg of cobalt (II) nitrate hexahydrate in 1.2 ml oo biyo ah DDI] ilaa 1 g nano H- ZSM-5 iyadoo si taxadir leh loo rog-rogayo firileyda.Suufka ayaa lagu qallajiyey laambad hoosteeda, waxaana la sameeyay budo casaan ah oo isku mid ah.Budada sida loo sameeyay ayaa markaa lagu shubay tuubo calcination toos ah waxaana lagu nadiifiyaa socodka argon hoostiisa (100 ml/min) 1 saac si loo yareeyo huurka.Ka-talisiyaha sida loo sii diyaariyay ayaa markaa lagu shubay qulqulka oksijiinta (60 ml/min) iyadoo xadiga kor u kaca ah ee 10°C/min ilaa 450° (lagu hayo 250°C, 350°C, iyo 450°C 1 saac midkiiba) .Co/ZSM-5 ee la helay waxay leedahay rarid kobalt ah 5 wt %.Laba rashiin oo kale, 3 iyo 7 wt %, ayaa sidoo kale la diyaariyey.Dhammaan seddexda wax-soo-dejiye waxaa lagu gartey hoos u dhigista heerkulka-barnaamijka H2, kala-duwanaanta raajada, raajada sawir-qaadista, iyo spectroscopy-ka muuqda ee ultraviolet.

Sifeynta Au-ka koobanSifeynta Au-ka kooban (Au + cC8═OOH-x) waxay ku jirtay goobta laga keenay Au/SiO2-catalyzed cC8═ falcelinta epioxidation iyadoo loo eegayo nidaamka ay soo saareen Qian et al.(2) Kahor falcelinta, cC8═ waa la nadiifiyay si looga saaro soo saaraha ku daray xasiliyaha.Guud ahaan, 50 ml oo ah 3 M potassium hydroxide (KOH) xal ayaa lagu daray 50 ml oo cC8═ galaas ah.Ka dib markii la isku daro ku filan iyo walaaqin xoog leh, lakabka organic waxaa lagu soo ururiyay kala soocid.Nidaamkan ayaa lagu soo celiyay 50 ml oo 3 M KOH ah iyo laba kale oo 50 ml oo biyo DDI ah.CC8═ ka dib waxaa lagu qallajiyey sodium sulfate habeenkii.Si gebi ahaanba meesha looga saaro xasiliyaha, cC8═ engegan ayaa lagu shubay qubeyska saliidda oo ku dhow 180°C, iyo jajabkii ka soo baxay 145°C ayaa la ururiyey.CC8═ oo la safeeyey (10 ml) iyo decane (1 ml) ayaa lagu qasay reactor ka kooban 80 mg oo ah kicinta Au/SiO2 ee aan soo sheegnay.CC8═ falcelinta epioxidation-ka waxaa lagu sameeyay socodka oksijiinta (30 ml/min) 100°C, beddeliddana waxaa kormeeray GC.Marka beddelaadkii la rabay la gaaro, isku darka falcelinta ayaa la ururiyay oo kicinta adag ayaa laga saaray sifeynta kulul iyadoo la adeegsanayo filtarrada saliingaha.Fiirinta caadiga ah ee AU-da ee lagu go'aamiyay in si firfircoon loogu lamaanay balasmaha spectrometry mass spectrometry waxay ahayd qiyaastii 80 ng/ml, cabirka kooxda Au waxaa lagu go'aamiyay spectroscopy fluorescence iyo aberration- saxay gudbinta elektarooniga microscopy u dhaxaysa atomyada ilaa ~0.7 nm.cC8═OOH-x waxaa loo diyaariyey si la mid ah iyadoo aan la isticmaalin Au/SiO2 kicinta.Labada xal ee Au + cC8═OOH-x iyo cC8═OOH-x waxay ka kooban yihiin cC8═ oxidation-ka, oo ay ku jiraan cycloocten oxide, cycloocten 3-hydroperoxide, 2-cycloocten-1-ol, 2-cycloocten-1-hal, iyo xaddi raadraac ee 1,2-cyclooctanediol.

Habka guud.Dareen-celinta oksaydhka EB ayaa lagu sameeyay gudcurka dab-dhaliye cylindrical saddex-luug ah oo ku qalabaysan tuubo firdhiye ah oo quraarad ah (Chemglass Life Sciences) iyo kondenser lagu hayo -10°C.Dareen-celin caadi ah, 7 ml oo EB ah, 1 ml oo decane ah, iyo 3 ml oo shaandhayn ah (Au + cC8═OOH-x ama cC8═OOH-x) ayaa lagu shubay reactor-ka oo ay la socdaan kicinta birta ee Teflon-dahaarka leh.Haddii la isticmaalo, 32 mg 5% Co/ZSM-5, ilaa si kale loo cayimin, ayaa lagu daray.Ka dib markii habaynta falcelinta la ururiyey, isku darka falcelinta ayaa lagu dejiyay socodka N2 ee 20 min ee qubeyska saliidda ee preheated.Marka heerkulka qaboojiyaha iyo qubeyska saliidda la dejiyo, socodka O2 joogto ah ayaa la bixiyay 30 ml/min.Isku darka falcelinta (0.1 ml) ayaa la qaatay waqtiyo kala duwan si loo falanqeeyo (shaandhada saliingaha ayaa la isticmaalay markii kiciyayaal adagi ay lug ku leeyihiin), lagu milmay 0.7 ml d-chloroform, waxaana lagu falanqeeyay 1H resonance magnetka nukliyeerka (NMR).

Aqoonsiga badeecada iyo xisaabinta.Aliquots ee isku darka falcelinta ayaa lagu qasi jiray tetrahydrofuran waxaana lagu falanqeeyay gaaska chromatography-mass spectrometry (GC-MS; Agilent GC-7890A, MS-5975).Dareen-celinta EB-ga, acetophenone iyo 1-phenylethanol ayaa loo aqoonsaday inay yihiin badeecadaha ugu badan.1H-NMR iyo 13C-NMR (400 MHz Agilent DD2-MR400 system) ayaa loo isticmaalay si loo sii xaqiijiyo aqoonsiga alaabta.1-Phenylethyl hydroperoxide, oo aan lagu ogaan GC-MS sababtoo ah degganaansho la'aanteeda kulaylka, ayaa NMR u aqoonsaday inay tahay badeecad kale oo weyn.Dhammaan saddexda alaab waxa lagu qiyaasey 1H-NMR iyadoo la isticmaalayo decane sida heerka gudaha (fig. S1).Luminta uumiga ayaa si gaar ah loo go'aamiyay waxaana loo adeegsaday in lagu saxo uruurinta alaabta.Ka dib markii la saxo khasaaraha uumi-baxa, dheellitir la'aanta kaarboon laguma arag falcelinta EB.Dareen-celinta cycloocten, cyclooctane oxide, cyclooctane-1,2-diol, 2-cycloocten-1-ol, iyo 2-cycloocten-1-one ayaa lagu qiyaasey GC.Cyclooctene 3-hydroperoxide ma ahayn mid deggan oo ka go'ay tiirka GC sidaas darteed lama ogaan.Waxaa jiray qiyaastii 10% luminta kaarboonka marka si buuxda loo beddelo xitaa ka dib markii la magdhabay khasaaraha uumi-baxa, taas oo lagu macnayn karo samaynta qadar yar oo ah alaabooyin oksaydhaysan oo aad u sarreeya oo aan la aqoonsan.

Xisaabinta beddelka iyo xulashada.Saamiga GC ama NMR ee molecule xiisaha iyo daanka heerka gudaha ayaa loo adeegsaday xisaabinta beddelka iyo xulashada.Inkasta oo qaboojiyaha la isticmaalay, haddana waxay ahayd lagama maarmaan in la magdhabo khasaaraha uumi-baxa sababtoo ah heerkulka falcelinta sare iyo waqtiga falcelinta dheer.Qalloocyada sixitaanka uumi-baxa ayaa loo helay labadaba EB iyo cC8═ oo hoos imanaya nitrogen socodka oo caadi ahaan loo eegayo saamiga EB/decane ama cC8═/decane.Sababtoo ah EB iyo cC8═ waxay leeyihiin dhibco karkarin oo isku mid ah, qodobbada sixitaanka caadiga ah ee la helay labaduba waxay ahaayeen 0.0044 (saamiga caadiga ah ayaa hoos u dhacay saacaddii).

Qiyaasta hydroperoxide.Heerarka hydroperoxide waxaa lagu qiyaasay laba hab oo titration:

1) Triphenylphosphine (PPh3) titration.PPh3 (0.1 M gudaha EB) ayaa loo isticmaalay in lagu titrate shaybaarada hydroperoxide aan la garanayn, iyo barta dhamaadka waxaa lagu aqoonsaday strip EM Quant peroxide.31P-NMR ayaa loo isticmaalay si loo xaqiijiyo ka saarida dhamaystiran ee noocyada hydroperoxide.

2) Titration Iodometric.Muunad (0.2 ml) ayaa lagu daray 1 ml oo CHCl3/acetic acid ah (v/v = 1:2) iyo 6 ml oo 1 M KI ah.Isku darka waxaa lagu walaaqay mugdiga 2 saacadood ka dibna lagu titrate 0.005 M Na2S2O3 iyadoo ay joogaan dhowr dhibcood oo istaarij ah.Dhammaadkii waxaa la gaaray markii isku darka uu noqday mid aan midab lahayn.

Labada habba waxay ahaayeen kuwo gudaha ah oo iswaafaqsan;si kastaba ha ahaatee, natiijooyinkoodu waxay ku kala duwan yihiin 5 ilaa 10%.Sababtoo ah Au + cC8═OOH-x iyo cC8═OOH-x ee loo adeegsaday mashruucan waxaa lagu soo saaray oksidation-ka cC8═OOH-bilaabantay, diirada hydroperoxide way ka duwan tahay dufc ilaa dufcad laakiin had iyo jeer waxay ku dhex jireen inta u dhaxaysa 0.2 ilaa 0.5 M si cusub loo diyaariyey. cC8═OOH-40 ilaa cC8═OOH-100 muunado.Heerarka hydroperoxide ayaa si tartiib tartiib ah hoos ugu dhacay wakhtiga kaydinta.

EPR-dabin tijaabo ah.DMPO (23 μl) ayaa lagu daray 1 ml oo muunad ah si loo gaaro fiirsashada DMPO ee 0.2 M, iyo 20 mg ee Co/ZSM-5 ayaa lagu daray isku dhafka muunada ee tuubada tijaabada.Isku darka ayaa la soniced 1 daqiiqo si loo hakiyo kicinta, tanna waxaa ku xigtay kuleyliyaha 60 ° C ~ 10 daqiiqo.Qayb ka mid ah isku dhafka ayaa loo wareejiyay tuubo wareega ee borosilicate tube capillary (1.50 gudaha dhexroor × 1.80 dhexroor ka baxsan, Wale Apparatus), kaas oo lagu shaabadeeyey hal daraf-tuubadan ayaa markaa la geliyey Wilmad quartz X-band EPR tube ( Sigma-Aldrich).Muunadda waxa lagu qaboojiyey galinta tuubada EPR ee dareeraha N2.Isla markiiba ka hor inta aan la cabbirin spectra EPR, muunadku waa la dhalaalay.Mawjada Joogta ah (CW) Cabbirrada EPR-X-band ayaa lagu sameeyay heerkulka qolka iyadoo la adeegsanayo spectrometer Varian E-4 oo la beddelay iyadoo la adeegsanayo Dewar farta.

Tijaabada calaamadaynta Isotopic.Deuterated EB (d10-EB) ayaa loo adeegsaday tijaabin isku dar ah 6 ml oo cC8═OOH-45, 5 ml d10-EB, 1 ml of decane, iyo 60 mg ee Co-ZSM-5 (7%) , at 120°C, oo leh 6 ml oo cC8═OOH-45, 5 ml of EB-d10, iyo 1 ml oo ah dodecane.Si loo magdhabo hoos u dhaca heerka falcelinta sababtoo ah saamaynta isotope ee kinetic, co-oxidation ayaa lagu sameeyay heerkul sare oo ah 120 ° C.Saliid muunad ah ayaa la qaaday kahor iyo kadib 24 saacadood oo falcelin ah waxaana falanqeeyay 2H-NMR iyo GC-MS.

2H-NMR spectrum (fig. S5, spectrum 2) waxay muujisay dhowr sare oo cusub ka dib falcelinta, oo aan joogin ka hor falcelinta, at δ1.50, δ1.58, δ4.94, δ7.42 to δ7.72, iyo δ8.04 .Sababtoo ah hoos u dhaca isku xidhka J-isku-xidhka joogtada ah iyo dareenka 2H-NMR, qaababka kala qaybinta lama xalin.Meelaha ugu sarreeya ee δ8.04 iyo δ7.42 ilaa δ7.72 ayaa loo qoondeeyey deuterons ee giraanta udgoonka ee acetophenone;ugu sarreeya ee δ1.50 iyo δ4.94 ayaa loo qoondeeyey methyl iyo benzylic deuteron ee 1-phenylethanol, siday u kala horreeyaan;iyo heerka ugu sarreeya ee δ1.58 ayaa loo qoondeeyay deuteron ee D2O oo laga sameeyay burburka hydroperoxide.Lama helin deuteron oo la xidhiidha wax soo saarka cycloocectene epoxidation, iyo samaynta biyaha deuterated waxay muujisay in sidayaal silsilad xagjir ah oo ugu muhiimsan falcelinta co-oxidation ay ahaayeen peroxy iyo alkoxy ku salaysan.

GC-MS spectra alaabta waxa lagu muujiyay berdaha.S6.Acetophenone-d8 (m/e 128, si buuxda loo deuterated, fig. S6A, m/e 127 iyo 126) ayaa la arkay.Laga soo bilaabo qaabka dildilaaca, dhammaan HD beddelka ayaa ka dhacay booska methyl.Intaa waxaa dheer, 1-phenylethanol-d9 (m/e 131) (fig. S6B) ayaa ahaa badeecada kaliya ee deuterated ee la ogaaday.Wax deuterium ah lagama helin cycloocectene oxide (fig. S6C), oo ah badeecada ugu badan ee ka timaada cyclooktene.1-Phenylethanol-d9 waxaa laga samayn karaa falcelinta phenylethoxy radical leh cyclooctene.

Waxyaabaha dheeriga ah ee maqaalkan ayaa laga heli karaa http://advances.sciencemag.org/cgi/content/full/6/5/eaax6637/DC1

Sawirka S5.2H-NMR ka hor (spectrum 1, red) iyo ka dib (spectrum 2, green) 24-saac falcelinta co-oxidation.

Sawirka S7.Isbarbardhigga beddelka bilowga ah ee 4-methyl anisole ee la bilaabay iyadoo la adeegsanayo Au + cC8═OOH-100, iyadoo cC8═OOH laga saaray.

Kani waa maqaal gelitaan furan oo lagu qaybiyey shuruudaha Shatiga Hal-abuurka Caadiga ah -Shatiga Aan Ganacsiga ahayn, kaas oo oggolaanaya isticmaalka, qaybinta, iyo taranka meel kasta, ilaa inta isticmaalka natiijadu aanu ahayn faa'iido ganacsi oo ay bixiso shaqada asalka ah ee saxda ah soo xigtay.

FIIRO GAAR AH: Waxaan kaliya ku codsaneynaa cinwaankaaga iimaylka si qofka aad u soo jeedineyso bogga uu ogaado inaad rabtay inay arkaan, oo aysan ahayn boostada junk.Ma qabno ciwaan email ah

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

Nidaamka catalytic-ka ee aan la-xidhiidhin, dhex-dhexaadiyeyaasha laga soo qaatay Au-catalyzed cyclooctene epioxidation oxidation ethylbenzene.

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

Nidaamka catalytic-ka ee aan la-xidhiidhin, dhex-dhexaadiyeyaasha laga soo qaatay Au-catalyzed cyclooctene epioxidation oxidation ethylbenzene.

© 2020 Ururka Maraykanka ee Horumarinta Sayniska.Dhammaan xuquuqaha way xifdisan yihiinAAAS waa lammaane HINARI, AGORA, OARE, CHORUS, CLOCKSS, CrossRef iyo COUNTER. Horumarka Sayniska ISSN 2375-2548.