芳基卤素，先进行钯催化的偶联反应，引入叔丁基醚，然后酸性去除叔丁基，可得羟基，苯酚类似物实验操作AsuspensionofPd(OAc)2(34.7g,0.15mol)andrac-BINAP(288.7g,0.46mol)intoluene(56.1L)wasstirredat40°Cfor30minundernitrogenatmosphere.Themixturewascooledto25°C,and25(5.90kg,15.47mol),tert-butanol(2.92L,30.94mol),tBuONa(2.23kg,23.2mol),andtoluene(2.95L)wereadded.Afterstirringat25°Cfor20min,thesolut...[
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(5a)cis-Isomerwithpartial1D1HNMRspectra.Farright,isthesimplifiedspectrumafterH1decouplingtoreveal3J2,3.(5b)trans-IsomerandsimplifiedpartofthespectrumonthefarrightafterH4decouplingtoreveal3J2,3.{H1}denotesH1decouplingand{H4}denotesH4decoupling.13Cchemicalshiftsofcompound8a(N-analogue)andcompound8b(O-analogue).[
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胺的氮烷基化反应是有机合成和医药研发中非常重要的一类反应，常用的方法有取代反应，还原胺化反应，Mitsunobu反应等等。在众多胺的类型中，有一大类特殊的胺的烷基化反应，那就是缺电子（杂）芳胺氮的烷基化反应。还原胺化反应用的最多的三个还原剂是：氰基硼氢化钠，三乙酰基硼氢化钠，和硼氢化钠。以下图的邻硝基苯胺为例，使用三乙酰基硼氢化钠/1，2-二氯乙烷[
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Usedtirestreadcanbeupto90%,buttheaverageis6-8/32”.Tiresingoodconditionshouldhaveaminimumof6/32”tobeuseful,or4/32”ifthetireis13-14”.Theaveragelegalminimumtreaddepthis2/32”,butdrivingbecomesunsafewithsuchatread.Besides,mostdealershipsrequireatleast4/32”treadtotrade-inacarwithoutprioratirechange.
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Wa...[
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Weathering
Weatheringisamajorfactorforthetiresonyourvehicle.Theyareendlesslyexposedtotheelements(heat,cold,snow,iceandwater).Becauserubberisanaturalmaterialandwillbreakdownovertime,youneedtobeawareofthepotentialsignsofweathering.Commonindicatorsarefinecracksinthesidewallandinbetweenthetreadblocks.Ifyoudodiscoverthesecracks(whichwillexposetheinternalmaterialsofthetiretotheelements),yourtires...[
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InpreviouspostsonthisBLOG,examplesof1H/2Hand12C/13Cisotopeeffectswerediscussed.Thefigurebelowshowsanexampleofa10B/11Bisotopeeffectobservedinthe19FNMRspectrumoftetrabutylammoniumtetrafluorobarate.Thespectrumclearlyshowstworesonancesseparatedby0.05ppmwithanintensityratioofapproximately20:80correspondingtothenaturalabundancesof10Band11B,respectively.Thelowfrequencyresonanceisdueto11BF4-.Since11Bisasp...[
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Theappearanceofthe1HNMRsignalsofproticsamplesinaproticsolventsdependscriticallyontheconcentrationofthesample.The-OH,-NH2or-COOHsignalscanhavechemicalshiftvaluesandlinewidthsoverawiderangeduetovaryingextentsofhydrogenbondingandchemicalexchange.TheconcentrationcanalsodeterminewhetherornotoneisabletoobserveJcouplingbetweenand-OHprotonandotherprotonsinthesample.Anexampleofthisisillustratedbelow.Thefig...[
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在试管中加入少量（麦粒大小）待结晶物，加入0.5mL根据上述规律所选择溶剂，加热沸腾几分钟，看溶质是否溶解。若溶解，用自来水冲试管外测，看是否有晶体析出。[
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WhyAre1HNMRIntegrationsNotPerfect?AnInquiry-BasedExerciseforExploringtheRelationshipbetweenSpinDynamicsandNMRIntegrationintheOrganicLaboratorHaimWeizmanDepartmentofChemistryandBiochemistry,UniversityofCalifornia,SanDiego,LaJolla,CA92093-0303;hweizman@ucsd.edu
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