1976年，英國牛津大學的J.E.Baldwin報道了各類分子內關環反應的難易程度的法則。此法則被稱為鮑德溫規則(Baldwin’sRule)。分子內關環反應的難易程度與關環部位的軌道相互作用息息相關。Baldwin法則就是用來總結這些規律的一個法則，同時該法則可適用範圍很廣，包括親核、親電、自由基環化反應。熵效應、立體電子效應、環張力等因素都考慮在內，總結出了以下幾點經驗規[閱讀全文]
博文
(2022-12-23 09:55:27)
1976年，英國牛津大學的J.E.Baldwin報道了各類分子內關環反應的難易程度的法則。此法則被稱為鮑德溫規則(Baldwin’sRule)。分子內關環反應的難易程度與關環部位的軌道相互作用息息相關。Baldwin法則就是用來總結這些規律的一個法則，同時該法則可適用範圍很廣，包括親核、親電、自由基環化反應。熵效應、立體電子效應、環張力等因素都考慮在內，總結出了以下幾點經驗規[閱讀全文]
(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.
[閱讀全文]
(2022-12-17 21:16:27)
Eschenmoser斷裂反應（埃申莫瑟斷裂），又稱Eschenmoser-Tanabe斷裂反應，是對甲苯磺酰肼使α,β-環氧酮斷裂生成含炔基和酮基化合物的反應。也譯為碎片化反應、碎裂反應。反應以瑞士化學家埃爾伯特·埃申莫瑟（AlbertEschenmoser）的名字命名。原料α,β-環氧酮可通過α,β-不飽和羰基化合物與過氧化氫在堿性條件下反應得到。首先α,β-環氧酮1與芳基磺酰[閱讀全文]
(2022-12-17 21:00:21)
Eschweiler(埃施韋勒)–Clarke反應TheEschweiler-Clarkereactionisanorganicreactionusedtoconvertaprimaryorsecondaryaminetoatertiaryamineusingformaldehydeandformicacid.Thisisessentiallyanaminemethylationprocesswhichbeginswiththereactionoftheaminestartingmaterialwiththeprotonatedformaldehydetoprovideanintermediateiminiumion.Theiminiumionthenreactswiththeformicacidtogiveamethylatedammoniumionandrele...[閱讀全文]
(2022-12-15 19:59:52)
TheStobbecondensationisamodificationspecificforthediethylesterofsuccinicacidrequiringlessstrongbases.Anexampleisitsreactionwithbenzophenone:Areactionmechanismthatexplainstheformationofbothanestergroupandacarboxylicacidgroupiscenteredonalactoneintermediate(5):[閱讀全文]
(2022-12-14 18:48:39)
TheNozaki–Hiyama–Kishireactionisanickel/chromiumcouplingreactionforminganalcoholfromthereactionofanaldehydewithanallylorvinylhalide.Intheiroriginal1977publication,TamejiroHiyamaandHitoshiNozakireportedonachromium(II)saltsolutionpreparedbyreductionofchromicchloridebylithiumaluminiumhydridetowhichwasaddedbenzaldehydeandallylchloride:ComparedtoGrignardreactions,thisreactionisveryselective...[閱讀全文]
(2022-12-11 14:18:30)
TheStaudingersynthesis,alsocalledtheStaudingerketene-iminecycloaddition,isachemicalsynthesisinwhichanimine1reactswithaketene2throughanon-photochemical2+2cycloadditiontoproduceaβ-lactam3.Thereactioncarriesparticularimportanceinthesynthesisofβ-lactamantibiotics.TheStaudingersynthesisshouldnotbeconfusedwiththeStaudingerreaction,aphosphineorphosphitereactionusedtoreduceazidestoamines.Thefirs...[閱讀全文]
(2022-11-20 17:44:23)
Removingpollutantsfromtheairinyourhomemeansyouandyourfamilycanbreathecleaner.Italsomeansyoucanbreatheeasierknowingthatyourheatingandcoolingsystemisn'tbeingoverworkedandraisingyourutilitybills.That'sbecausedirtcancausefurnaceorairconditionerfailureandanACorfurnacefilter'smainjobistostopdirtanddustfromenteringyourequipment. Unfortunately,filtershaveashortlifespanbecausetheyfillupquick...[閱讀全文]
(2022-11-14 18:09:33)
氫是構成有機化合物的重要元素，核磁共振氫譜通過相關氫的化學位移、耦合裂分以及積分等為有機化合物的結構解析提供了大量有價值的信息。烷氫、烯氫、炔氫、芳香氫以及醛基氫等常規氫在氫譜裏的表現特征性很強歸屬較容易。相對這類氫原子，活潑氫的解析就要複雜得多。所謂活潑氫是指有一定的酸性，容易離去或容易發生交換的氫，一般在其周圍有強吸電子基團。[閱讀全文]
(2022-11-13 18:48:18)
Ifyourfurnaceisgivingyouheatingissues,thegasvalvemaybetheculprit. Thegasvalvemanifoldinsidethefurnaceopensandclosestoallowyourfurnacetoburngastocreateheat. Althoughmosttimesthereareotherthingsthatyoushouldcheckbeforeyoutroubleshootthegasvalve. Firstthingsfirst-checkthatthegassupplytoyourfurnaceisopen. Anotherthingtocheckistheswitchonthegasvalvebodyinsidethefurnace. Mostgasvalves...[閱讀全文]
