1、ContentslIntroduction(Research background)lThe different nitroxyl radicalslTEMPO-mediated alcohols oxidationlPINO(like)-mediated alcohols oxidationlConclusionsNON OOOTEMPOPINOIntroductionReaction equation:CHRROHCRRO+O2Catalyst system+H2OlAldehydes,ketones and acids are crucial industrial products.lT
2、he world-wide annual production of carbonyl compounds is over 10,000,000 tonnes and many of these compounds are produced from the oxidation of alcohols.lDirection:green,environment-friendly catalytic processes.lCatalytic system:transition metal,oxidase enzyme,The different nitroxyl radicalsNONONONON
3、 OOONSOOOOStable(presistent)radicals:inhibitorsReactive(non-persistent)radicals:catalystsTEMPOPINOSINOScheme 1 structures of organic nitroxyl radicalsNOONNNOSheldon,R.A.;Arends,I.W.C.E.J.Mol.Catal.A:Chemical,2006,251,200214TEMPO-mediated alcohol oxidationlRu/TEMPO catalytic systemlCu/TEMPO catalytic
4、 systemlLaccase/TEMPO catalytic systemlFe-NaNO2/TEMPO catalytic systemlTransition metal-free catalytic systemNONO+H+PH3NONOH+E0=0.53VRu/TEMPO catalytic systemR1R2OH0.5-2mol%Ru(PPh3)3Cl2TEMPOClPh,10bar air,100R1R2ODijksman,A.;Marino-Gonzalez,A.;Mairata i Payeras,A.etc.J.Am.Chem.Soc.2001,123,68266833E
5、ntrySubstrate S/C ratio Time(h)Conv.(%)TON 1 Octan-2-ol 100 7 98 98 2 Octan-1-ol 50 7 85 43 3 1-phenylethanol 100 4 99 100 4 cyclooctanol 100 7 92 92 5 Benzyl alcohol 200 2.5 99 200 6 Benzyl alcohol/1-phenylethanol 200 3 90/5 180/10 15 mmol of substrate,RuCl2(PPh3)3/TEMPO ratio of 1:3,30 mL chlorobe
6、nzeneTable 4 oxidation of alcohols by Ru/TEMPO systemRu/TEMPO catalyzed oxidation mechanismRuCl2(PPh3)32R1R2CHOH2R1R2CO+2HClRuH2L3(L=PPh3)RuL3HHCOR1R2-H eliminationR1R2CONOL3RuH(a)R1R2CHOHNOHNONHO1/2 O2H2O+2NHinert atm.Shedon,R.A.;Arends,I.W.C.E.;Brink,G.-J.T.;etc.,Accounts of Chemical Research,2002
7、,35,9,774-781Sheldon,R.A.;Arends,I.W.C.E.;Adv.Synth.Catal.2004,346,10511071Scheme 3 Ru-catalyzed oxidation of alcohols with molecular oxygenCu(I)/TEMPO system for alcohols oxidationR1R2OHTEMPO(5mol%),CuCl(5mol%)O2,bmimPF6,65R1R2OR1=aryls.alkyls;R2=H,alkylsOHentryalcoholproducttime(h)conversionyield1
8、15987221697903159796436967558398736169890Ansari,I.A.;Gree,R.Org.Lett.2002,4,15071509CHOOHMeOCHOMeOOHNO2CHONO2NOHNCHOOHOCH2OHCHOBenzyl alcohol(108 mg,1.0 mmol)1.5 mL bmimPF6;1 atm O2 Table 1 oxidation of alcohol by Cu(I)/TEMPO systemSchultz,M.J.and Sigman,M.S.Tetrahedron,2006,62,82278241Oxidation of
9、aliphatic alcohols were not high efficient.Cu()/TEMPO catalytic systemNONOCuHH1NHONHOCuNOORHHHIIRROH5 mol%15mol%TEMPOToluene,O2,100RROVelusamy,S.;Srinivasan,A.and Punniyamurthy,T.Tetrahedron Letters,2006,47,923926NHONHOCuNOORRHHIIstertcally hirderedR=alkyl,arylEntry Substrate Product Time(h)Yield(%)
10、1 10972 1498399842190522 756122CH2OHCHOCH2OHO2NCHOO2NCH2OHMeOCHOMeOCH2OHCHOCH2OHCHOAlcohol(5 mmol)in toluene(10 mL)under atmospheric oxygenTable 2 oxidation of alcohols by Cu()/TEMPO systemOHOCu/TEMPO catalyzed oxidation mechanismO2H2OTEMPOHTEMPONNCuBr2AROHNNCuBBrORTEMPONNCuORNO+HCRO+TEMPOHNNCuBrDGa
11、mez,P.;Arends,I.W.C.E.;Sheldon,R.A.;Reedijk,J.Adv.Synth.Catal.2004,346,805811Scheme 2 Cu-TEMPO catalyzed aerobic alcohols oxidationRecent development of Cu-catalyzed systemR1R2OH4mol%Cu(ClO4)2,4mol%TMDP6mol%acetamido-TEMPO,O210mol%DABCO,DMSO,r.t.R1R2ONNTMDPNONHCOCH3Jiang,N.;Ragauskas,A.J.Org.Lett.20
12、05,7,36893692Acetamido-TEMPOEntryAlcoholProductTime(h)ConversionYield12100982299933298934241911529871629992CH2OHCHOCH2OHClCHOClPhOHPhCHOPhOHPhCHONCH2OHNCHOSCH2OHSCHOAlcohol(2 mmol),under 1 atm oxygenJiang,N.and Ragauskas,A.J.,J.Org.Chem.2006,71,7078-7090Table 3 oxidation of alcohols by Cu(ClO4)2/TMD
13、P/DABCD/acetamido-TEMPO systemDACBO:1,4-diazabicyclo2.2.2octaneLaccase/TEMPO catalytic systemEntrySubstrateProductYield(%)1benzyl alcoholbenzaldehyde9223,4-dimethoxy benzyl alcohol3,4-dimethoxy benzaldehyde993cinnamyl alcoholcinnamaldehyde 9445-hexen-1-ol5-hexen-1-al195cyclohexanolcyclohexanone35Fab
14、brini,M.;Galli,C.and Gentili,P.etc.Tetrahedron Letters 2001,42,75517553NO+CH2OHRN+CRHOOHHBCHOR+NOHNONOHLaccaseReaction conditions:subst.:20 mM,TEMPO:6 mM,3 U/mL of laccase,3 mL water(pH 4.5);time:24h;r.t.Table 6 Oxidation of Alcohols by Laccase-TEMPO catalytic systemScheme 4 the mechanism of alcohol
15、s oxidation by Laccase/TEMPO system It mainly catalyzed oxidation of aclohols with rich electrons.Recent development of Laccase-catalyzed systemOH+O2OTEMPO(like)LaccaseEntryMediatorAcetate bufferWater/toluene1TEMPO66.827.624-hydroxy-TEMPO76.860.734-acetylamino-TEMPO78.581.7NOOHArends,I.W.C.E.;Li,Y.;
16、Ausan,R.and Sheldon,R.A.Tetrahedron 2006,62,66596665NONHCOCH3Sub0:125 mM,Lac:5.9 U/ml,Med:19 mM,rt,1 atm O24-hydroxy-TEMPO4-acetylamino-TEMPOTable 7 oxidation of benzyl alcohol by Laccase/TEMPO-like systemFe-NaNO2/TEMPO systemR1R25 mol%FeCl3-6H2O5mol%NaNO22mol%TEMPOPHCF3,air,rtOHR1R2OEntrysubstrate
17、Time(h)Conversion(%)1 8 99 2899312 99412 9958 99PhOHp-Me-PhOHp-Cl-PhOHSOHOHWang,N.;Liu,R.;Chen,J.;Liang,X.Chem.Commun.2005,53225324substrate:10 mmol,PhCF3:10 mL Table 5 oxidation of alcohols by Fe-NaNO2/TEMPO systemTransition metal-free TEMPO-mediated catalytic systemEntry Substrate Product Time Con
18、v.(%)Select.(%)Yield(%)111001009521.5100999833-C8H17OH 3-Octanone 499.1 99.3 88 4410099.4895594.4100-CH2OHCHOOHOOHONCH2OHNCHOLiu,R.;Liang,X.;Dong,C.and Hu,X.J.Am.Chem.Soc.2004,126,4112-4113 Table 8 oxidation of alcohols by TEMPO/NaNO2/Br2 systemReaction conditions:substrate(10 mmol),TEMPO(0.1 mmol),
19、Br2(0.4 mmol),CH2Cl2(10 mL),80,NaNO2(0.4 mmol),0.4 MPa air pressure The oxidation mechanism by TEMPO-Br2-NaNO2 systemO2NO2NOHBrBr2R1NO+NOHR2OHR1R2OH2O Thereinto,the use of NO to activate molecular oxygen plays a crucial role in the TEMPO/Br2/NaNO2 catalytic oxidation cycle.Scheme 5 oxidation of alco
20、hols by TEMPO-Br2-NaNO2 systemSupported-TEMPO-mediated catalytic systemNOHONaHBrNOOH2PtCl6(MeO)3SiHNOO(MeO)3SiMCM-41NOOSiOOONHN(CH2)6NNH*NNN*NH(tert-octyl)5Na2WO42H2O30%H2O2CH2Cl2/MeOHNON(CH2)6NNO*NNN*NH(tert-octyl)5Dijksman,A.;Arends,I.W.C.E.;Sheldon,R.A.Synlett 2001,102104.Oxidation results by sup
21、ported-TEMPOEntryCatalystS/C Time(h)Conv.(%)TOF 1 PIPO 10020 45 2.3 2 PIPO 101.5 96 6.43 MCM-41 TEMPO 10024 20 0.9 4 SiO2 TEMPO 10020 4 0.210mmol benzyl alcohol,CuCl:nitroxyl=1:1,25ml DMF,25,oxygen atmosphereTable 9 Oxidation of benzyl alcohol by different supported TEMPORecent development of mediat
22、ors foralcohols oxidationQian,W.;Jin,E.;.Bao,W.and Zhang,Y.Tetrahedron 2006,62,556562Shibuya,M.;Tomizawa,M.;Suzuki,I.and Iwabuchi,Y.J.Am.Chem.Soc.2006,128,8412-8413NN+BF4-ONONN+BF4-ONOONN+BF4-ONOONOion-suppotedTEMPONONOexpandedaccessibilityenhanced catalytic efficiencyimproved nitroxy radical origin
23、ated from TEMPOPINO-mediated alcohols oxidationlHeteropoly acid/NHPI catalytic systemlCo/NHPI catalytic systemlV/NHPI catalytic systemN OOON OHOO+e-e+H+E0=1.08VNHPIHeteropoly acid/NHPI catalytic systemRRRROHON OHOON OOO1/2 O2H2OPMoVoxPMoVred1/2 O2H2OentrySubstrate Time(h)Yield(%)15 (41)(23)25 (56)OH
24、Ishii,Y.;Nakayama,K.;Takeno,M.;Sakaguchi,S.;Iwahama,T.;Nishiyama,Y.J.Org.Chem.1995,60,3934-3935HOOHOOHOSubstrate(2 mmol)was reacted in the presence of NHPI(10mol%)in PhCN(5 mL),100,under a dioxygen atmosphereTable 10 oxidation of alcohols by heteropoly acid/NHPI system Iwahama,T.;Yoshino,Y.;Keitoku,
25、T.;Sakaguchi,S.;Ishii,Y.J.Org.Chem.2000,65,65026507Co/NHPI catalytic systemR1R2OHR1R2O0.5mol%Co(OAc)210mol%NHPI5mol%MCBAEtOAc,O2,rtentrySubstrate Time(h)Yield(%)115982206732075420835207862084PhOHOHOHOHOHPhOHPhOHAlcohol(3 mmol),AcOEt(5 mL)Table 11 oxidation of alcohols by Co/NHPI system V/NHPI cataly
26、tic systemRROHRCOOHRRONHPI,Vn+,RX or amineMeCN,50-75,1 atm O2 1-22hRX=LiCl,Bu4NCl;amine=Py,4-Me-PyVn+=VO(acac)2,VO(OPr)3,Bu4NVO3P.J.Figiel,J.M.Sobczak and J.J.Zilkowski,Chem.Commun.,2004,244-245Entry Alcohol Co-catalyst Conversion(%)Time/h Selectivity(%)1Cyclohexanol VO(acac)2+Bu4NCl 90.3 18 66.4 2C
27、yclohexanol VO(acac)2+LiCl 81.7 2 100 3Cyclohexanol VO(acac)2Cl 89.2 18 60.1 4Cyclohexanol VO(OPr)3+LiCl 80.1 1 89.0 52-Pentanol VO(acac)2+LiCl 96.4 20 99 61-Hexanol VO(acac)2+LiCl 100 22 96.6 5 mmol substrate,75Table 12 oxidation of alcohols by V/NHPI system SINO-mediated alcohols oxidationNSOOOOHN
28、SOOOO-e+H+entryalcohol Time(h)Conversion(%)Product Yield(%)15 93 92 23 96 9432 100 984986 6754100100 OHOOHOPhOHPhOOHOHOPhOHPhOHOBaucherel,X.;Gonsalvi,L.;Arends,I.W.C.E.;Ellwood,S.and Sheldon,R.A.Adv.Synth.Catal.2004,346,286-296Subatrate(4.5 mmol),NHS(0.45 mmol),Co(acac)3(0.022 mmol),PhCO2H(0.22 mmol
29、),butyl acetate(7.5 mL),O2 1 atm,100Table 13 oxidation of alcohols by SINO-mediated system Mechanism of oxidation mediated by PINO(like)RROHN OOON OHOORROHO2RRHOOOHMn+RRON OHOON OOO+Mn-1+Mn+initiatory periodScheme 6 oxidation of alcohols by PINO-mediated systemConclusionslEfficient and green oxidati
30、on of alcohols have been achieved in the presence nitroxyl radical and co-catalyst;lTEMPO and PINO(analogs)mediated catalytic system combination with a transition metal were broadly applied in alcohols oxidation;lNaNO2 and other non-transition-metal can also be employed co-catalyst for aerobic oxidation of alcohols;lMetal-free catalytic system containing nitroxyl radical can be further improved;lSome more efficient modified nitroxyl radical can be developed.
