1976年，英国牛津大学的J.E.Baldwin报道了各类分子内关环反应的难易程度的法则。此法则被称为鲍德温规则(Baldwin’sRule)。分子内关环反应的难易程度与关环部位的轨道相互作用息息相关。Baldwin法则就是用来总结这些规律的一个法则，同时该法则可适用范围很广，包括亲核、亲电、自由基环化反应。熵效应、立体电子效应、环张力等因素都考虑在内，总结出了以下几点经验规[阅读全文]
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(2022-12-23 09:55:27)
1976年，英国牛津大学的J.E.Baldwin报道了各类分子内关环反应的难易程度的法则。此法则被称为鲍德温规则(Baldwin’sRule)。分子内关环反应的难易程度与关环部位的轨道相互作用息息相关。Baldwin法则就是用来总结这些规律的一个法则，同时该法则可适用范围很广，包括亲核、亲电、自由基环化反应。熵效应、立体电子效应、环张力等因素都考虑在内，总结出了以下几点经验规[阅读全文]
(2022-12-23 08:47:00)
Chloroformformsaverypoisonouscompoundcalledphosgene(COCl2)whenstoredforalongtimebyreactingwithoxygeninpresenceofsunlight.
CHCl3+1/2O2→COCl2+HCl
Inordertoconsumethatphosgenegasandmakechloroformsafe,itismixedwithethanol.
OCCl2+2HOC2H5→O=C(OC2H5)2+2HCl
Asaresult,ifyourcompoundcontainsalcoholaensitivegroup,suchasacidchlorid,donotuseusechlorformassolvent.
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(2022-12-17 21:16:27)
Eschenmoser断裂反应（埃申莫瑟断裂），又称Eschenmoser-Tanabe断裂反应，是对甲苯磺酰肼使α,β-环氧酮断裂生成含炔基和酮基化合物的反应。也译为碎片化反应、碎裂反应。反应以瑞士化学家埃尔伯特·埃申莫瑟（AlbertEschenmoser）的名字命名。原料α,β-环氧酮可通过α,β-不饱和羰基化合物与过氧化氢在碱性条件下反应得到。首先α,β-环氧酮1与芳基磺酰[阅读全文]
(2022-12-17 21:00:21)
Eschweiler(埃施韦勒)–Clarke反应TheEschweiler-Clarkereactionisanorganicreactionusedtoconvertaprimaryorsecondaryaminetoatertiaryamineusingformaldehydeandformicacid.Thisisessentiallyanaminemethylationprocesswhichbeginswiththereactionoftheaminestartingmaterialwiththeprotonatedformaldehydetoprovideanintermediateiminiumion.Theiminiumionthenreactswiththeformicacidtogiveamethylatedammoniumionandrele...[阅读全文]
(2022-12-15 19:59:52)
TheStobbecondensationisamodificationspecificforthediethylesterofsuccinicacidrequiringlessstrongbases.Anexampleisitsreactionwithbenzophenone:Areactionmechanismthatexplainstheformationofbothanestergroupandacarboxylicacidgroupiscenteredonalactoneintermediate(5):[阅读全文]
(2022-12-14 18:48:39)
TheNozaki–Hiyama–Kishireactionisanickel/chromiumcouplingreactionforminganalcoholfromthereactionofanaldehydewithanallylorvinylhalide.Intheiroriginal1977publication,TamejiroHiyamaandHitoshiNozakireportedonachromium(II)saltsolutionpreparedbyreductionofchromicchloridebylithiumaluminiumhydridetowhichwasaddedbenzaldehydeandallylchloride:ComparedtoGrignardreactions,thisreactionisveryselective...[阅读全文]
(2022-12-11 14:18:30)
TheStaudingersynthesis,alsocalledtheStaudingerketene-iminecycloaddition,isachemicalsynthesisinwhichanimine1reactswithaketene2throughanon-photochemical2+2cycloadditiontoproduceaβ-lactam3.Thereactioncarriesparticularimportanceinthesynthesisofβ-lactamantibiotics.TheStaudingersynthesisshouldnotbeconfusedwiththeStaudingerreaction,aphosphineorphosphitereactionusedtoreduceazidestoamines.Thefirs...[阅读全文]
(2022-11-20 17:44:23)
Removingpollutantsfromtheairinyourhomemeansyouandyourfamilycanbreathecleaner.Italsomeansyoucanbreatheeasierknowingthatyourheatingandcoolingsystemisn'tbeingoverworkedandraisingyourutilitybills.That'sbecausedirtcancausefurnaceorairconditionerfailureandanACorfurnacefilter'smainjobistostopdirtanddustfromenteringyourequipment. Unfortunately,filtershaveashortlifespanbecausetheyfillupquick...[阅读全文]
(2022-11-14 18:09:33)
氢是构成有机化合物的重要元素，核磁共振氢谱通过相关氢的化学位移、耦合裂分以及积分等为有机化合物的结构解析提供了大量有价值的信息。烷氢、烯氢、炔氢、芳香氢以及醛基氢等常规氢在氢谱里的表现特征性很强归属较容易。相对这类氢原子，活泼氢的解析就要复杂得多。所谓活泼氢是指有一定的酸性，容易离去或容易发生交换的氢，一般在其周围有强吸电子基团。[阅读全文]
(2022-11-13 18:48:18)
Ifyourfurnaceisgivingyouheatingissues,thegasvalvemaybetheculprit. Thegasvalvemanifoldinsidethefurnaceopensandclosestoallowyourfurnacetoburngastocreateheat. Althoughmosttimesthereareotherthingsthatyoushouldcheckbeforeyoutroubleshootthegasvalve. Firstthingsfirst-checkthatthegassupplytoyourfurnaceisopen. Anotherthingtocheckistheswitchonthegasvalvebodyinsidethefurnace. Mostgasvalves...[阅读全文]
