有机化学实验翻译件

PAGEPAGE8有机化学实验讲义

实验操作实验一、溴乙烷的制备目的和要求

1、学习从结构上相对应的醇为原料制备一卤代烷的原理和方法。

2、学习低沸点物蒸馏的基本操作。

3、掌握萃取的原理和方法。二、反应原理用乙醇、溴化纳及硫酸作用是制备溴乙烷常用的方法。

NaBr+H2SO4→HBr+NaHSO4

C2H5OH+HBr→C2H5Br+H2O

溴乙烷的沸点很低（38.4℃上式的制备反应是一个可逆反应,通常可以采用增加其中一种反应物的浓度或设法移走产物使溴乙烷及时离开反应体系的方法,使平衡向右移动。本实验正是两种措施并用,以使反应顺利完成。

若H2SO4浓度太大，又会引起一系列副反应。

H2SO4＋2HBr→SO2+2H2O+Br2

2C2H5OH→C2H5－O－C2H5

+H2O

C2H5OH→CH2=CH2+H2O反应混合物中水量太少。HBr气体容易在操作时逃逸而使反应不完全。但是由于这个反应是可逆的，水的用量太大，也不利于反应的完全，因此，反应混合物中水的量是需要讨论的第一个关键问题。药品试剂，操作步骤

药品：乙醇（95%）10mL(7.9g,0.165mol)；溴化钠（无水）13g（0.126mol）；浓硫酸19mL(0.34mol)；饱和亚硫酸氢钠溶液。操作步骤：在100mL园底烧瓶中加入13g研细的溴化钠，然后放入9mL水，振荡使之溶解，再加入10mL95%乙醇，在不断振摇和冰水冷却下，漫漫加入19mL浓硫酸，同时用冰水浴冷至室温，加入2~3粒沸石，安装成常压蒸馏装置（参见图）。为了避免挥发损失，在接收器中加冷水及5mL饱和亚硫酸氢钠溶液，接受器内外均应放冰水混合物，以防止产品的挥发损失。接液管的支管用橡皮管到入下水道或室外。将反应混合物在石棉网上小火加热，瓶中物质开始发泡，控制火焰大小，使油状物质逐渐蒸馏出去，约30min后慢慢加大火焰，到无油滴蒸出为止。流出物为乳白油状物，沉于瓶底。将馏出液倒入分液漏斗中，分出的有机层置于干燥的小锥形瓶中，在冰水浴中，边振摇边滴加浓硫酸，直至锥形瓶底分出硫酸层为止（约需4mL浓硫酸）。用干燥的分液漏斗仔细地分去下面的硫酸液，将溴乙烷粗产品从上口倒入干燥的蒸馏瓶中。装配蒸馏装置，加2~3粒沸石，用水浴加热，蒸馏溴乙烷。收集37~40℃的馏分。称量、计算产率（产品重约10g）。纯溴乙烷的b.p.38.4℃，d反应装置四、操作要点及注意事项1、反应开始时，加热不可太猛，否则蒸出的油层还有较深的黄色，这可能是HBr受硫酸氧化所致，再者加热太猛时，反应瓶中的物质起泡严重，有可能冲到冷凝管中。

2、溴乙烷沸点低（38.4℃），产物极易挥发损失，因此，反应完毕后，应将粗产物暂保留在接受器水层以下。先准备好后面所用的干燥仪器（小锥形瓶、分液漏斗）、蒸馏装置，然后进行分离，精制、洗涤。

3、粗产物中的水分一定要分离干净，然后在冷却下加入浓H2SO4，如果水分不尽，加浓H2SO4时将发热，使产物挥发、损失。另一方面浓H2SO4五、思考题1、溴乙烷的制备中浓H2SO4洗涤的目的何在？

2、溴乙烷沸点低（38.4℃ExperimentⅠThepreparationofbromoethaneAPurposeandrequirementsLearntheprinciplesandmethodsforpreparingbromoethanefromethanol.Learnthebasicoperationoflowboilingpointdistillation.Mastertheprinciplesandmethodsofextraction.BReactionprinciplesThecommonmethodsofpreparingbromoethanefromEthanol,sodiumbromideandsulfuricacidareasfollows.

NaBr+H2SO4→HBr+NaHSO4

C2H5OH+HBr→C2H5Br+H2O

Ethylbromidehasalowboilingpoint(38.4℃Thereactionformulaaboveforpreparingisareversibleone,whichcouldbeusuallymadegoforwardwhentheconcentrationofonereactantisincreasedorthebromoethaneproductisremovedtimely.Inthisexperiment,twokindsofmeasuresareusedsimultaneouslytomakethereactioncomplicated.

ToolargeconcentrationoftheH2SO4wouldcauseaseriesofsideeffects.

H2SO4+2HBr→SO2+2H2O+Br2

2C2H5OH→C2H5-O-C2H5+H2O

C2H5OH→CH2=CH2+H2OSincetoolittlewaterinthereactionmixturewillbeveryeasyforHBrgastoescapeduringtheoperation,leavingthereactionincomplete，whiletoomuchwaterisalsonotconducivetocompletethereaction,soitisthefirstkeyissuetokeeptheamountofwaterinthereactionmixture.CPharmaceuticalagentandstepsDrugs:Ethanol(95%)10mL(7.9g,0.165mol);Sodiumbromide(anhydrous)13g(0.126mol);Concentratedsulfuricacid19mL(0.34mol);Saturatedsolutionofsodiumhydrogensulfite.Procedure:Addthemashedsodiumbromide13ginto100mLroundbottomflaskbeforeadding9mLofwaterintoit,thenshaketheflasktodissolvethesodiumbromideandadd10mL95%ethanol.Injectconcentratedsulfuricacid19mLslowlywhentheflaskisshakencontinuouslyandcooledwithice,whilewaterbaththesolutionwithanicetocoolittoroomtemperatureatthesame.setupanatmosphericdistillationunitafteradding2-3zeolites(refertotheFigure).5mLwaterwithsaturatedsodiumhydrogensulfitesolutionshouldbeaddedintothereceivertopreventvolatilization,whileputicewatermixtureinsideandoutsidethereceivertoreducetheevaporationlossofproduct.BranchoftheWettedpipewhichwillledwastewatertotheseweroroutdoorswillbeconnectedtothehose.Thereactionmixturewillbeheatedontheasbestoswiregauzewithasmallfire,pleaseadjusttheflametodistilltheoilysubstanceoffgraduallywhenthematerialinthebottlestartstofoam,thenincreasetheflameslowlyafterabout30minuntilnodropletscanbesteamedup.Themilkyoileffluentwillsanktothebottom.Pourthedistillateintoaseparatoryfunnelandtheseparatedorganiclayerintoasmalldriedconicalflaskwhichisplacedinice-waterbath.Dropwiseiaddconcentratedsulfuricacidwhileshakingtheflaskuntiltheacidlayerwasseparatedunderthebottomofconicalflask(about4mLofconcentratedsulfuricacid).Separatethesulfuricacidcarefullywithdryfunnelandpourthecrudeproductethylbromideintodrydistillationflaskfromthetopbottleneck.Assemblethedistillationapparatus,thenwaterbathheatingittodistillatebromoethaneafteradding2to3zeolitesintoit.Weighthecollectedfractions(about10g)at37~40℃tocalculatetheyield.Theb.p.ofpurebromoethaneis38.4℃andd420ReactionequipmentDTheoperatingpointsandprecautions1,Theheatingmustnotbetoofierceatthestartofthereaction,ortherewillbeadarkyellowinthereservoirsteamedout,whichmaybecausedbytheoxidationofHBrbysulfuricacid.Besides,thesubstanceinflaskwillfoamtoosevereandmaybewashedintothecondenserwhenheatedtoofast.2,Sincetheethylbromidehasalowboilingpoint(38.4℃),itisveryeasyfortheproducttovolatilizationloss.Therefore,thecrudeproductshouldbetemporarilyretainedbelowtheaqueouslayerinthereceiverwhenthereactionfinished.Preparethedryingapparatus(smallconicalflask,funnel)anddistillationapparatuswellwhichwillbeusedlater,afterwhichwewillseparate,purifyandwashtheproduct3,WaterinthecrudeproductmustbeseparatedcompletelybeforeputtingtheconcentratedH2SO4withrefrigeration,ifthewaterisnotremovedcompletely,theheatgavenoutwhenaddingconcentratedH2SO4willmaketheproductvolatilizationloss.Ontheotherhand,theeffectofconcentratedH2SO4istoremovetheethanolandethyletherintheproduct.4,Thisisthefirstexperimentusingaseparatoryfunnel,studentsshouldlearntheprinciples,usablerangeandhandlingprecautionsofit.

EQuestions1．WhatisthepurposeofwashingwithconcentratedH2SO4in2．Ethylbromidehasalowboilingpoint(38.4℃),what’sthemeasurestakenintheexperimenttoreducethelossofethylbromide实验二、乙酸乙酯的制备一、实验目的：掌握用醇和羧酸制备酯的方法。练习分液漏斗的使用及蒸馏操作二、试剂：1、乙醇23mL（0.37mol）2、冰醋酸14.3mL(15g,0.23、浓硫酸4、饱和碳酸钠水溶液5、饱和食盐水6、饱和氯化钙7、无水硫酸镁(用于干燥乙酸乙酯)三、反应原理：乙酸和乙醇在浓硫酸催化下直接酯化生成乙酸乙酯。主反应：CH3CH3COOH+CH3CH2OH110～125℃CH3COOCH2CH3+H2副反应：2CH2CH3CH2OHH2SO4C2H5OC2H5+H四、仪器与反应装置图：仪器100mL三口圆底烧瓶；温度计（150℃）；滴液漏斗（60mL）；分液漏斗（100mL）；锥形瓶（50mL2个）装置图图1实验装置图2蒸馏装置五、操作步骤：在100mL三口烧瓶的一侧口配装一滴液漏斗，将滴液漏斗的下端伸到烧瓶内离瓶底约3mm处，另一侧口固定一温度计，中口装配一分馏柱、蒸馏头、温度计及直型冷凝管，冷凝管末端连接尾接管及锥型瓶，锥型瓶用冰水浴冷却。在一小锥型瓶内放入3mL乙醇，一边摇动一边慢慢地加入3mL浓硫酸，将此溶液倒入三口瓶中。配置20mL乙醇和14.3mL冰醋酸的混合液，倒入滴液漏斗中。加热烧瓶，控制反应混合物的温度为120℃左右，然后把滴液漏斗中的乙醇和冰醋酸的混合液慢慢地滴入三口瓶中，调节加料的速度，保持加料和蒸出速度大致相等，加料时间约需90min。继续保持反应混合物的温度120将饱和碳酸钠水溶液缓慢地滴加到流出液中，边加边摇动接收器，直到无二氧化碳气体逸出为止。把混合液倒入分液漏斗中，静置，放出下面的水层。用红色石蕊试纸检验酯层。如果酯层仍然显酸性，再用饱和碳酸钠水溶液洗涤，直到酯层不显酸性为止。用等体积的饱和食盐水洗涤，再用等体积的饱和氯化钙溶液洗涤两次，放出下层废液从分液漏斗上口将乙酸乙酯倒入干燥的小锥型瓶内，加入无水硫酸镁干燥。放置约30min，在此期间要间歇地振荡锥型瓶。通过长颈漏斗（漏斗上放折叠式滤纸），把干燥后的粗乙酸乙酯滤到50mL蒸馏烧瓶中，装配蒸馏装置，在水浴上加热蒸馏，收集74~78℃的馏分。产量约14.5~16.5纯的乙酸乙酯为具有果香味的无色液体，b.p.77.2℃，d4六、注意事项：1、酯化反应所用仪器必须无水，包括量取乙醇和冰醋酸的量筒也要干燥。2、加热之前一定将反应混合物混合均匀，否则容易炭化。3、分液漏斗的正确使用和维护。。4、用10％碳酸钠水溶液洗涤有机相时有二氧化碳产生，注意及时给分液漏斗放气，以免气体冲开分液漏斗的塞子而损失产品。5、正确进行蒸馏操作，温度计的位置影响流出温度，温度计水银球的上沿与蒸馏头下沿一平。6、有机相干燥要彻底，不要把干燥剂转移到蒸馏烧瓶中。7、反应和蒸馏时不要忘记加沸石。表主要试剂的物理常数[1]用量及规格名称构造式分子量（M）熔点/℃（mp）沸点/℃(bp)密度(d420)水中溶解度g/100g用量（）规格乙醇乙酸C2H5OHCH3COOH46.660.05-117.316.678.5117.97899;0.8014(95%)1.0492∞∞28mL18mL化学纯化学纯七、思考题1、在本实验中浓硫酸起什么作用？反应中，浓硫酸除了起催化剂作用外，还吸收反应生成的水，有利于酯的生成。2、为什么要用过量的乙醇？使平衡向生成物一方移动3、蒸出的粗乙酸乙酯中主要有哪些杂质？主要杂质有乙醚、乙醇、乙酸和水等。4、用饱和氯化钙溶液洗涤能除去什么？酯层中含有少量未反应的乙醇，由于乙醇和CaCl2作用生成CaCl2·4H2O结晶化物，除去0少量未反应的乙醇。ExperimentIIPreparationofEthylacetateAPurposeoftheexperiment1,Masterthemethodofpreparingesterswithalcoholandcarboxylic.2,Practicetheapplicationmethodofseparatoryfunnelanddistillationoperation.BThereagents1,Ethanol23mL(0.37mol)2,Glacialaceticacid14.3mL(15g,0.25mol)3,Concentratedsulfuricacid4,Saturatedaqueoussodiumcarbonate5,Saturatedbrine6,Saturatedcalciumchloride7,Anhydrousmagnesiumsulfate(fordryingtheethylacetate)CThereactionprincipleEsterificationofaceticacidandethanolcangenerateethylacetatedirectlywithconcentratedsulfuricacidcatalyzing.Mainreaction:CH3COOH+CH3CH2OH110～125℃CH3COOCH2CH3+H2OSide-effects:2CH3CH2OH+H2SO4C2H5OC2H5+H2ODTheinstrumentandthereactionequipmentdiagramInstrument100mLroundbottomflaskwiththreenecks;thermometer(150℃);droppingfunnel(60mL);separatoryfunnel(100mL);conicalflask(50mL2items);straightcondenser;distillationhead;acceptablebendhead;heatingsystem.DeviceFigure

Figure1ExperimentalsetupFigure2DistillationunitEOperatingstepsEquipthe100mLthree-neckedflaskwithadroppingfunnelinoneofthesidemouthsandathermometerintheotherone,extendthelowerendofthedroppingfunnelabout3mmuptothebottomoftheflask.Adistillationcolumnwithdistillationhead,thermometerandstraightcondenserwillbeassembledinthemiddlemouth,connecttheendofcondenserpipewithataperedtailendandaconicalflaskcooledwithicewater.Put3mLethanolintoasmallconicalflask,andthenadd3mLofconcentratedsulfuricacidslowlywhileshakingit,pourthesolutionintoathree-neckedbottle.Pouramixtureofethanol20mLandglacialaceticacid14.3mLintoadroppingfunnel,andtheninstillthemixtureinthedroppingfunnelintoathree-neckedflask,trytoadjustthespeedofchargingandsteamingoutroughlyequal.Thereactionmixtureshouldbeheatedandcontrolledtobeabout120℃,adjustthespeedofaddingtomaintainsubstantiallyequaltosteam,theaddingtimeisabout90min.Keepthereactionmixturetemperatureabout120℃,goonheatingaftertheadditioniscompletedabout10minuntilthereisnomoreliquidoutflowDropwiseaddingthesaturatedaqueoussodiumcarbonatesolutionintotheeffluentslowlywhileshakingthereceiveruntilnomorecarbondioxidegasescapesfromit.Pourthemixtureintoaseparatoryfunnelandletouttheloweraqueouslayerafterstatichierarchical.Testtheesterlayerwithredlitmuspaper,andthenwashtheesterlayerbysaturatedaqueoussodiumcarbonatesolutionuntilitisnomoreacidic.Itwillalsobewashedbyanequalvolumeofsaturatedbrineonceaswellasanequalvolumeofasaturatedcalciumchloridesolutiontwice,afterwhichtheethylacetatewillbepouredintoasmalldriedconicalflaskfromtheupperopeningoftheseparatingfunnel.Addanhydrousmagnesiumsulfateasadryingagentandlaytheethylacetateaside30min,duringwhichtimeflaskshouldbeoscillatedintermittently.Filterthedriedcrudeethylacetateto50mLcrudedistillationflaskthroughlong-neckedfunnel(withfoldedfilterpaper),heatdistillationitinawaterbathandcollectthe74~78℃distillateafterequippingthedistillationunit.Theyieldwillbeabout14.5~16.5gPureethylacetateiscolorlessliquidwithafruity,bp77.2℃,d420FNotes1,Theinstrumentsusedforesterificationreactionmustbeanhydrous,themeasuringcylindertomeasureethanolandaceticacidshouldalsobedry.2,Thereactionmixtureshouldbehomogeneouslymixedbeforeheated,oritcanbecarbonizedeasily.3,Properlyuseandmaintenanceoftheseparatoryfunnel.4,Carbondioxidewillbeproducedwhenwashingtheorganicphasewith10%aqueoussodiumcarbonate,attentionshouldbetooktodeflatedtheseparatoryfunneltopreventthelossofproductswhentheplugopeningoftheseparatoryfunnelisburstbygas.5,Operatethedistillationproperly,asthepositionofthethermometeraffecttheoutflowtemperatureeffect,weshouldputthetopedgeofthemercurybulbthermometeralongtheloweredgeofthedistillinghead.6,Theorganicphaseshouldbedriedthoroughlyandpleasedon’ttransferthedesiccanttothedistillationflask.7,Donotforgettoaddzeolitesbeforethereactionanddistillation.TablePhysicalconstants,dosageandspecificationsofmainreagentsNameCondensedStructuralFormulasMolecularweight（M）Fusionpoint/℃（mp）Boilingpoint/℃(bp)Density(d420)Watersolubilityg/100gDosage（）NormsEthanolAceticacidC2H5OHCH3COOH46.660.05-117.316.678.5117.97899;0.8014(95%)1.0492∞∞28mL18mLPurePureGQuestions1．Whateffectsdoestheconcentratedsulfurichaveinthisexperiment?2．Whyanover-dosealcoholshouldbeused?3．Whatarethemainimpuritiesinthecrudeethylacetatesteamedout?4．Whatcanberemovedifwashedbyasaturatedsolutionofcalciumchloride?实验三、苯甲酸的制备一、实验目的1.了解相转移催化剂的催化原理。2.掌握热滤、抽滤、回流、重结晶等操作技能。二、合成反应式三、实验仪器及装置圆底烧瓶、回流冷凝管、布氏漏斗、抽滤瓶等加热回流装置四、实验步骤在250mL锥型瓶中加入1.4mL甲苯和50mL水，瓶口装回流冷凝管，搅拌加热至沸腾。从冷凝管上口分批加入4.3g1.4mL甲苯1.4mL甲苯50mL水高锰酸钾4.3g几粒沸石加热分数次加入KMNO4少量水冲洗冷凝管内壁加热回流2~3h时常摇动烧瓶油层消失停止反应将反应混合物趁热用水泵减压过滤，并用少量热水洗涤滤渣（二氧化锰），合并滤液和洗液，放在冰水浴中冷却，用浓盐酸酸化（用刚果红试纸检验），直到苯甲酸全部析出。抽滤、压干。若产品不够纯净，可用热水重结晶，必要时加少量活性炭脱色。产量约0.9g，纯苯甲酸为白色针状晶体，熔点为五、实验注意事项1、高锰酸钾分批加入，避免反应激烈从回流管上端喷出。2、非均相反应应摇动装置，使反应充分。六、思考题1、加料时如何避免瓶口附着高锰酸钾？实验完毕后，粘附在瓶壁上的黑色固体物是什么？如何除去？该方法是否适合实验室氧化其它类型的带有支链的芳烃来制备苯甲酸？在提倡建立环境友好型社会的今天，该方法可否适用于工业制备？工业上是采用何种方法制备苯甲酸的？ExperimentⅢPreparationofbenzoicacidAThepurposeoftheexperiment1,Knowabouttheprinciplesofphase-transfercatalysts.2,Masteroperationskillsofhotfiltration,filtration,refluxandrecrystallization.BThesynthesisreactionformulaCLaboratoryequipmentandapparatusHeatingrefluxdevices:Round-bottomedflask

RefluxcondenserBuchnerfunnel,FiltrationbottlesandsoonDTheexperimentalprocedureMix1.4mLtolueneand50mLwaterin250mLconicalflaskandinstallarefluxcondenserinthebottleneck,thenstirandheatittoboiling.Addthepotassiumpermanganate4.3gfromtheupperlipofcondenserpipeinbatches,thepotassiumpermanganateadheredtotheinnerwallofthecondensershouldbewashedintotheendofthebottlewith25mLwater.Continuetoboilandshaketheflaskintermittentlyuntilthetoluenelayeralmosttodisappear,andnomorerefluxliquidoildropletswouldappear(about4~5h).Thehotmixtureshouldbefilteredunderreducedpressurewithapump,andtheresidue(manganesedioxide)bewashedwithalittlehotwater,thenthecombinedfiltrateandwashingliquorwillbecooledinanicebathandbeacidifiedwithconcentratedhydrochloricacid(testwithCongoredpaper)untiltheprecipitationofbenzeneformicacidisfinished.Filtrateandpresstheproduct.Whilewecanalsorecrystaltheproductinhotwateroraddalittleactivecarbonwhenitisnotpureenough.Theoutputwillbeabout0.9g.Purebenzoicacidiswhiteneedle-shapedcrystalwithameltingpointof122.4EExperimentalconsiderations1,Potassiumpermanganateshouldbeaddedinbatchestopreventthereactiontoointensetoejectfromtheupperendofthereturnpipe.2,Apparatusshouldbeshakentomaketheheterogeneousreactionfullyrealize.FQuestions1,Howtoavoidthepotassiumpermanganatestickingtobottleattached?2,Whatistheblacksolidadheringtothesidewallofthebottleattheendtheexperiment?Howtoremoveit?3,Isthemethodsuitableforoxidationofothertypesaromatichydrocarbonswithabranchedchaintopreparebenzoicacidinlaboratory?4,Couldthemethodbeappliedfortheindustrialpreparationastheenvironmental-friendlysocietyisbeingpromotedtoday?Whatmethodisusedforpreparingbenzoicacidindustrially?实验四、乙酰水杨酸的制备一、实验目的学习以酚类化合物作原料制备酯的原理和实验方法，巩固重结晶操作方法。二、实验原理三、实验装置（无特殊装置。）四、试剂与仪器试剂：水杨酸、乙酸酐、浓硫酸、10％碳酸氢钠溶液，20％盐酸，1％三氯化铁溶液仪器：锥形瓶（50mL）、烧杯、抽滤装置五、实验步骤在100mL锥形瓶中依次加入3.2g水杨酸（0.023mol），4mL乙酸酐（0.04mol将锥形瓶置于60～70OC的热水浴中，加热20min，并不时地振摇。然后，停止加热，待反应混合物冷却至室温后，缓缓加入（到）100mL水（中），边加水边振摇(注意，反应放热，操作应小心)。将锥形瓶放在冷水浴中冷却15min有晶体析出，抽滤，并用少量冰水洗涤2次，抽干，得乙酰水杨酸粗产品。将粗产品转入到100mL烧杯中，加入10％碳酸氢钠水溶液，边加边搅拌，直到不再有二氧化碳产生为止。抽滤，除去不溶性聚合物(水杨酸自身聚合)。再将滤液倒入100mL烧杯中，缓缓加入10mL20％盐酸，边加边搅拌，，这时会有晶体逐渐析出。将此反应混合物置于冰水浴中，使晶体尽量析出。抽滤，用少量冰水洗涤2～3次，然后抽干，取少量乙酰水杨,溶入几滴乙醇中，并滴加1～2滴1％三氯化铁溶液，如果发生显色反应，说明仍有水杨酸存在，产物可用乙醇－水混合溶剂重结晶：即先将粗产品溶于少量沸乙醇中，再向乙醇溶液中添加热水直至溶液中出现混浊，再加热至溶液澄清透明（注意：加热不能太久，以防乙酰水杨酸分解），静置慢慢冷却、过滤、干燥、称重、测定熔点并计算产率。乙酰水杨酸受热易分解，熔点不明显，测定时，可先加热至110OC左右，再将待测样品置入其中测定。六、注意事项1．

乙酸酐和浓硫酸均具有腐蚀性，量取时应小心。2．

反应结束后，多余的乙酸酐发生水解，这是放热反应，操作应小心。3．

在重结晶时，其溶液不宜加热过久，也不宜用高沸点溶剂，因为在高温下乙酰水杨酸易发生分解。七、实验结果与讨论乙酰水杨酸为白色针状晶体，熔点132～135OC，称量，计算产率，测定熔点。八．思考题1．

水杨酸与乙酸酐的反应过程中浓硫酸起什么作用？2．

纯的乙酰水杨酸不会与三氯化铁溶液发生显色反应。然而，在乙醇－水混合溶剂中经重结晶的乙酰水杨酸，有时反而会与三氯化铁溶液发生显色反应，这是为什么？3．

水杨酸与乙酸酐反应结束后，如果不采用碳酸氢钠成盐、盐酸酸化的方法分离聚合物杂质，可否加拟定一个分离的方案？4.在硫酸从在下，水杨酸与乙醇作用会得到什么产品？5.试比较苄醇、苯酚和水杨酸乙酰化速度。6.醇、酚、糖的酯化有什么不同？ExperimentⅣPreparationofacetylsalicylicacidI.PurposeoftheexperimentLearntheprinciplesandexperimentalmethodsofesterspreparationwithphenoliccompounds,consolidatetheoperationmethodofrecrystallization.II.Experimentalprinciple III.Theexperimentaldevice(nospecial)IV.ReagentsandinstrumentsReagents:salicylicacid,aceticanhydride,concentratedsulfuricacid,10%sodiumbicarbonatesolution,20%hydrochloricacid,1%ferricchloridesolutionInstrument:flask(50mL),beakers,suctionmeansV.TheexperimentalprocedureAdd3.2gsalicylicacid(0.023mol),4mLaceticanhydride(0.04mol)and5dropsofconcentratedsulfuricacidinto100mLErlenmeyerflask,shakeittomakesalicylicaciddissolve.Placetheflaskintoa60~70℃waterbathandheatfor20min,shaketheflaskfromtimetotimewhenitwasheated.Thenaddthereactionmixtureinto100mLofwaterslowlywhenitiscooledtotheroomtemperature,addwaterwhenshakingtheconicalflask(Pleasebecarefuloftheoperationbecauseitisexothermic).Thencooltheflaskinacoldwaterbathfor15min.Leachandwashittwicewithasmallamountoficewaterafterthecrystalsprecipitation,thendrainittogetacrudeproductofacetylsalicylicacid.Transferthecrudeproducttoa100mLbeakerandthenadd10%aqueoussodiumbicarbonate,stirthemixturewhileaddingthesodiumbicarbonateuntilnomorecarbondioxidecomesintobeing.Filtrateittoremovetheinsolublepolymer(Acidwillpolymerizebyitself).Thenpourthefiltrateinto100mLbeaker,add10mL20%hydrochloricacidslowlywhilestirring,crystalswillbeprecipitatedgraduallyatthistime.Placethereactionmixtureintoice-watertomakethecrystalsseparateoutasmoreaspossible.Filtrateandwashitwithasmallamountoficewaterfor2-3times,takealittleacetylsalicylicanddissolveitintoafewdropsofethanolafterthecrystalsdraining,dropwiseadd1to2dropsof1%ferricchloridesolution,thecolorreactionindicatethatsalicylicacidisstillinthesolution,theproductcanberecrystallizedfromthemixturebyethanol-water:Firstlydissolvethecrudeproductintoasmallamountofboilingethanolandthenaddtheethanolsolutionuntilthesolutionappearscloudy,thenheatittoclearandtransparent(Note:longtimeheatingshouldbepreventedtopreventitsdecomposition),waituntilthesolutioncoolslowly,filtrate,dry,weigh,measureandcalculatetheyieldaswellasitsmeltpoint.Theacetylsalicylicacidwillbedecompositedeasily,youcanheatittoabout110℃andthenmeasuresampleforitsmeltingpointisnotobvious,.VI.Notes1.Youshouldbecarefulwhileweighingaceticanhydrideandconcentratedsulfuricacidfortheyarecorrosive.2.Theexcessaceticanhydridewillbehydrolyzedaftercompletionofthereaction,pleasebecarefulthatitisanexothermicreaction.3.Thesolutionshouldnotbeheatedtoolongwhilerecrystalizing,andthehighboilingsolventshouldbepreferredbecausetheacetylsalicylicaciddecomposeeasilyathightemperature.VII.ResultsanddiscussionAcetylsalicylicacidiswhiteneedle-likecrystalwithmeltingpointof132~135℃,weighandcalculatetheyield,determinatethemeltingpoint.VIII.Questions1.Whatistheroleofconcentratedsulfuricacidinthereactionprocessofsalicylicacidandaceticanhydride?2.Pureacetylsalicylicacidwillnothavecolorreactionwithferricchloridesolution.However,sometimescolorreactionwilltakeplacefromacetylsalicylicrecrystaledinethanol–watermixedsolventwiththeferricchloridesolution,why?3.Afterthesalicylicacidreactionwithaceticanhydride,canapreparedseparatesolutionbeaddedtoseparatepolymerimpuritieswithoutadoptingacid-baseneutralizationwithsodiumbicarbonateandacidificationbyhydrochloricacid?4．Whatwilltheproductbefromthereactionofsalicylicacidandethylalcoholwiththeexistenceofsulfuricacid?5.Comparethespeedofbenzylalcohol,phenolandsalicylicacidacetylating.6.Whatisthedifferencesbetweenalcohols,phenolsandsugaresterification?实验五、甲基橙的制备一、实验目的

熟悉重氮化反应和偶合反应的原理，掌握甲基橙的制备方法。二、实验原理1、重氮化反应2、偶合反应

三、药品和仪器药品：对氨基苯磺酸

5%氢氧化钠、10%氢氧化钠

亚硝酸钠

浓盐酸

冰醋酸N,N-二甲基苯胺

乙醇乙醚

淀粉-碘化钾试纸仪器：烧杯

温度计

表面皿四、实验操作1、重氮盐的制备(一).重氮盐的制备：1.100mL烧杯中放入2.1g（0.01mol）对氨基苯磺酸晶体，加入10mL棒搅拌下，在热水浴中温热使之溶解[1]。2.冷至室温后加入0.8g（0.011mol3.搅拌下[2]，将上述混合溶液分批滴入盛有13mL水和2.5mL浓盐酸的烧杯中，并控制温度在5℃以下[3]4.滴加完后用淀粉-碘化钾试纸检验[4]。然后在冰盐浴中放置15min，使重氮化反应完全。(二).偶合反应：5.取一支试管，加入1.3mL（1.2g,0.01mol）N,N-二甲基苯胺和1mL6.不断搅拌下将此溶液慢慢加到上述冷却的重氮盐溶液中，加完后继续搅拌15min，使偶合反应进行完全。7.搅拌下慢慢加入15mL10%氢氧化钠溶液，反应物变为橙色[5]，粗制的甲基橙呈细粒状沉淀析出。8.将反应物在沸水浴上加热5min使沉淀溶解，冷却至室温后再置于冰水浴中冷却，甲基橙全部重新结晶析出。9.抽滤，晶体用少量水洗涤，压干[6]。10.若要制得纯度较高的产品，可用溶有少量氢氧化钠（约0.15g11.称重，计算产率。产量约2克，产率约为75%。12.溶解少许产品于水中，加几滴稀盐酸，然后用稀氢氧化钠溶液中和，观察溶液颜色有何变化。纯甲基橙是橙黄色片状晶体，没有明确熔点。pH3.1(红)～pH4.4(橙黄)。五、注意事项:[1]对氨基苯磺酸是两性化合物，其酸性略强于碱性，所以它能溶于碱中而不溶于酸中.[2]为了使对氨基苯磺酸完全重氮化,反应过程必须不断搅拌.[3]重氮化反应过程中控制温度很重要,若温度高于5℃[4]若不显兰色,尚需酌情补加亚硝酸钠溶液.若亚硝酸已过量,可用尿素水溶液使其分解.[5]这时反应液呈弱碱性,若呈中性,则继续加入少量碱液至恰呈碱性,因强碱性又易产生成树脂状聚合物而得不到所需产物.[6]湿的甲基橙在空气中受光照射后,颜色会很快变深,故一般得紫红色粗产物,如再依次用乙醇,乙醚洗涤晶体,可使其迅速干燥.六、思考题1、在重氮盐制备前为什么还要加入氢氧化钠？如果直接将对氨基苯磺酸与盐酸混合后，再加入亚硝酸钠溶液进行重氮化操作行吗？为什么?

2、制备重氮盐为什么要维持0-5℃3、重氮化为什么要在强酸条件下进行？偶合反应为什么要在弱酸条件下进行ExperimentⅤPreparationofMethylorangeI.PurposeoftheexperimentTrytobe

familiarwiththeprinciplesofdiazotizationandcouplingreaction,aswellastomasterthemethodofpreparingmethylorange.II.Theexperimentalprinciple1.Diazotization2.Couplingreaction

III.DrugsandequipmentDrugs:sulfanilicacid,5%sodiumhydroxide,10%sodiumhydroxide,sodiumnitrite,concentratedhydrochloricacid,glacialaceticacid,N,N-Dimethylaniline,ethylalcohol,diethyletherandstarch-potassiumiodidepaper.Instrument:beakers,thermometerandwatchglass.IV.ExperimentaloperationsPreparationofthediazoniumsalt(A)Preparationofthediazoniumsalt:1Put2.1g(0.01mol)sulfanilicacidcrystalloidinto100mLbeaker,thenputthebeakerinhotbathanddissolute10mL5%sodiumhydroxidesolutionwhilestirringwithglassrod.2Dissolve0.8g(0.011mol)ofsodiumnitritewhenthesolutioniscooledtotheroomtemperature.3Partiallydripthemixedsolutionintothebeakercontaining13mLwaterand2.5mLconcentratedhydrochloricacidwhilestirring,thetemperaturebelow5℃isneeded.4Testwithstarch-iodidepaperafterdroppingandthenplacethesolutioninanicebathfor15mintomakethediazotizationreactioncompletely.(B)Couplingreaction:5Shakethetesttubewith1.3mL(1.2g,0.01mol)N,N-Dimethylanilineand1mLglacialaceticacidtomixthem.6Addthesolutionslowlytothecooleddiazoniumsaltsolutionobtainedwhilestirringconstantly,stirthesolutionfor15mintomakethecouplingreactioncompletely.7Add15mL10%sodiumhydroxidesolutionslowlywhilestirringtoseethereactantturntoorange,thecrudemethylorangewillbeseparatedoutasfinelygranularprecipitate.8Heatthereactioninaboilingwaterbathfor5mintodissolvetheprecipitate,andthenputitintoanicebathafteritiscooledtotheroomtemperature,allthemethylorangewillrecrystallize.9Filtrateandthenwashthecrystalwithalittlewater,andthenpresstodryit.10Recrystallizefromboilingwaterwithsmallamountofsodiumhydroxide(about0.15g)willobtainhighpurityproducts.11Weightocalculatetheyield.Theproductionshouldbeabout2gandtheyieldshouldbeabout75%.12Dissolvealittleproductintowaterandaddafewdropsofdilutehydrochloricacidbeforeneutralizingwithdilutesodiumhydroxidesolution,trytoobservedthesolutioncolorchange.Puremethylorangeisorangeflakycrystalswithoutclearmeltingpoint.pHfrom3.1(red)topH4.4(orange).V.Notes:[1]Theaminoacidisamphotericcompoundwhichacidityisslightlystrongerthanitsalkalinity,soitcanbedissolvedintoalkalibutnotacid.[2]Inordertomakethediazotizationofsulfanilicacidcompletely,stirringcannotbestoppedduringreaction.[3]Thetemperaturecontrollingisveryimportanttothediazotizationreactionprocess,thediazoniumsaltiseasytobehydrolyzedtophenolswithloweryieldinatemperaturehigherthan5℃.[4]Ifsolutionisnotblue,thesodiumnitritesolutionisstillneededtobefilledin,whileifthenitrousacidisexcess,theureacanbeusedtodecomposethesolution.[5]Atthistimethereactionsolutionwillbealkalescency,continuetoaddasmallamountofalkalinelyetomakethesolutionexactlyalkalescencyifitisneutral,becauseitwillbeeasytogenerateresin-likepolymerinastronglyalkalinitysolution.[6]Wetmethylorangewillbecomedarkenquicklyirradiatedbylightintheair,that’swhyitisgenerallyapurplecrudeproduct.Methylorangecanbedriedquicklywhenthecrystalsarewashedwithethylalcoholanddiethylsuccessively.VI.Questions1Whythesodiumhydroxideshouldbeaddedinbeforethediazoniumsaltwasprepared?Willitbeallrightifthesulfanilicacidismixedwithhydrochloricaciddirectlyandthenaddinsodiumnitritesolution?Why?2Whythetemperatureshouldbemaintainedaround0-5℃topreparediazoniumsalt,andwhattheharmfuleffectswillbeinhightemperature?3Whythediazotizationshouldbeinstrongacidcondition?Whythecouplingreactionshouldbecarriedoutinweakacidiccondition?实验六.从茶叶中提取咖啡碱咖啡因具有刺激心脏、兴奋大脑神经和利尿等作用，因此可用作中枢神经兴奋药。它也是复方阿司匹林（APC）等药物的组分之一。咖啡因又名咖啡碱，属杂环化合物嘌呤的衍生物，它的化学名称为1，3，7—三甲基—2，6—二氧嘌呤，结构如下：嘌呤咖啡因1,3,7-三甲基-2,6-二氧嘌呤咖啡因易溶于氯仿（12.5%），水（2%）及乙醇（2%）等。含结晶水的咖啡因为无色针状晶体，在100℃时即失去结晶水，并开始升华，在120℃升华显著，178℃升华很快。一、实验目的：1、学习生物碱的提取方法；2、了解咖啡因的性质；3、学习脂肪提取器的作用和使用方法。二、实验原理：茶叶中含有咖啡因，约占1~5%，另外还含有11~12%的丹宁酸（鞣酸），0.6%的色素、纤维素、蛋白质等。为了提取茶叶中的咖啡因，可用适当的溶剂（如乙醇等）在脂肪提取器中连续萃取，然后蒸去溶剂，即得粗咖啡因。粗咖啡因中还含有其它一些生物碱和杂质（如单宁酸）等，可利用升华法进一步提纯。三、实验装置：图索氏脂肪提取器1