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魔力四射綠色化學(xué)
奮斗拼搏乙酰苯胺的制備摘要:對(duì)乙酰苯胺制備的微型實(shí)驗(yàn)條件進(jìn)行探討,確定乙酰苯胺制備微型實(shí)驗(yàn)的最佳條件。利用加熱蒸餾和重結(jié)晶法進(jìn)行制備和提純。獲得較高產(chǎn)率的乙酰苯胺。乙酰苯胺制備的微型實(shí)驗(yàn),利用較少量的試劑和較短的時(shí)間獲得了滿意的實(shí)驗(yàn)效果。乙酰苯胺是溫和的止痛藥和退熱藥,它在OTC藥物中占有重要地位。在第二次世界大戰(zhàn)的時(shí)候大量用于制造對(duì)乙酰氨基苯磺酰氯。乙酰苯胺也用于制硫代乙酰胺。在工業(yè)上可作橡膠硫化促進(jìn)劑、纖維脂涂料的穩(wěn)定劑、過(guò)氧化氫的穩(wěn)定劑,以及用于合成樟腦等。健康危害:吸入對(duì)上呼吸道有刺激性。高劑量攝入可引起高鐵血紅蛋白血癥和骨髓增生。反復(fù)接觸可發(fā)生紫紺。對(duì)皮膚有刺激性,可致皮炎。能抑制中樞神經(jīng)系統(tǒng)和心血管系統(tǒng),大量接觸會(huì)引起頭昏和面色蒼白等癥。乙酰苯胺可以通過(guò)苯胺與乙酰氯、乙酰酐或者冰醋酸等試劑進(jìn)行乙?;磻?yīng)制得。其中乙酰氯反應(yīng)最劇烈,乙酸酐次之,冰醋酸最慢。雖然用冰醋酸制取乙酰苯胺需要長(zhǎng)時(shí)間加熱,但此方法比較經(jīng)濟(jì),有商業(yè)意義。考慮到實(shí)驗(yàn)條件和經(jīng)濟(jì)因素,這個(gè)實(shí)驗(yàn)用冰醋酸來(lái)制取乙酰苯胺。Abstrate:PreparationofAcetanilidemicroexperimentalconditionstoexplore,determineacetanilidebestconditionsforpreparationofmicro-experiment.Theuseofheatingandre-crystallizationmethodreturnpreparationandpurification.Ahigheryieldofacetanilide.Acetanilidepreparationofmicro-experiments,theuseofsmalleramountsofreagentsandshortertimetoobtainasatisfactoryexperimentalresults.關(guān)鍵詞:乙酰苯胺重結(jié)晶(acetanilide,recrystallization)冰醋酸(aceticacid)熱過(guò)濾(hotfiltration)前言:分子式CH3COC6H4NH2,分子量135.1652CAS號(hào)103-84-4性質(zhì):白色有光澤片狀結(jié)晶或白色結(jié)晶粉末??扇?。無(wú)臭。在空氣中穩(wěn)定,呈中性。相對(duì)密度1.2190(15/4℃)。熔點(diǎn)114.3℃。沸點(diǎn)304℃。閃點(diǎn)173.9℃。自燃點(diǎn)546℃。微溶于冷水,溶于熱水、甲醇、乙醇、乙醚、氯仿、丙酮、甘油和苯等。用途:制藥、染料、橡膠硫化促進(jìn)劑、合成樟腦等毒性:由呼吸和消化系統(tǒng)進(jìn)入體內(nèi),能抑制中樞神經(jīng)系統(tǒng)和心血管系統(tǒng),大量接觸會(huì)引起頭昏和面色蒼白等癥。大鼠經(jīng)口LD50為800mg/kg。生產(chǎn)設(shè)備應(yīng)密閉。操作人員應(yīng)穿戴好防護(hù)用具,避免直接接觸。下班后用溫水沐浴。包裝儲(chǔ)運(yùn):采用內(nèi)層塑料袋、外層麻袋或帆布袋包裝,每袋凈重50kg。貯存在陰涼、干燥、通風(fēng)處,防火、防潮。用汽車(chē)或火車(chē)運(yùn)輸均可。按有毒化學(xué)品規(guī)定貯運(yùn)。實(shí)驗(yàn)部分一、實(shí)驗(yàn)?zāi)康?1、掌握制備乙酰苯胺的原理和方法2、進(jìn)一步學(xué)習(xí)重結(jié)晶和純化固體的操作方法二、實(shí)驗(yàn)原理::制備乙酰苯胺時(shí),常用的乙?;噭┯斜姿?、醋酸酐或乙酰氯等,當(dāng)采用乙?;噭r(shí)反應(yīng)最劇烈,醋酸次之,冰醋酸與苯胺反應(yīng)最慢,但反應(yīng)平穩(wěn)、易于控制,且冰醋酸價(jià)格較便宜,故本實(shí)驗(yàn)采用冰醋酸作乙酰化試劑。胺的?;谟袡C(jī)合成中有著重要的作用。作為一種保護(hù)措施,一級(jí)和二級(jí)芳胺在合成中通常被轉(zhuǎn)化為它們的乙酰基衍生物以降低胺對(duì)氧化降解的敏感性,使其不被反應(yīng)試劑破壞;同時(shí)氨基?;蠼档土税被谟H電取代反應(yīng)(特別是鹵化)中的活化能力,使其由很強(qiáng)的第Ⅰ類(lèi)定位基變?yōu)橹械葟?qiáng)度的第Ⅰ類(lèi)定位基,使反應(yīng)由多元取代變?yōu)橛杏玫囊辉〈?,由于乙?;目臻g位阻,往往選擇性的生成對(duì)位取代物。用冰醋酸為?;瘎┲苽湟阴1桨贰7及房捎悯B取⑺狒蚺c冰醋酸加熱來(lái)進(jìn)行?;褂帽姿嵩噭┮椎?,價(jià)格便宜,但需要較長(zhǎng)的反應(yīng)時(shí)間,適合于規(guī)模較大的制備。酸酐一般來(lái)說(shuō)是比酰氯更好的?;噭?。用游離胺與純乙酸酐進(jìn)行酰化時(shí),常伴有二乙酰胺[ArN(COCH3)2]副產(chǎn)物的生成。但如果在醋酸-醋酸鈉的緩沖溶液中進(jìn)行?;?,由于酸酐的水解速度比?;俣嚷枚?,可以得到高純度的產(chǎn)物。但這一方法不適合于硝基苯和其它堿性很弱的芳胺的?;?。該反應(yīng)是可逆反應(yīng),產(chǎn)率較低,為減少逆反應(yīng)的發(fā)生,得到較高的收率,可增加乙酸的用量,另外還采取分餾法,控制溫度在105到110度之間,不斷除去生成的水,有效地使平衡向正反應(yīng)方向移動(dòng)。由于苯胺易氧化,加入少量鋅粉,防止苯胺在反應(yīng)過(guò)程中氧化。純乙酰苯胺為白色片狀結(jié)晶,熔點(diǎn)為114度,稍溶于熱水、乙醇、乙醚、氯仿、丙酮等溶劑,而難溶于冷水,故可用熱水進(jìn)行重結(jié)晶。三、實(shí)驗(yàn)儀器與試劑:1儀器:50mL圓底燒瓶、50mL錐形瓶、燒杯、分餾柱、熱浴漏斗、150℃溫度計(jì)、抽濾裝置一套。2試劑:苯胺、冰醋酸、鋅粉、活性炭。四、實(shí)驗(yàn)裝置:(1)分餾裝置(2)熱過(guò)濾裝置(3)抽濾裝置五、實(shí)驗(yàn)步驟1.乙酰苯胺的合成在50ml圓底燒瓶中加入5ml新蒸餾的苯胺.7.5ml冰醋酸和0.1g鋅粉。在圓底燒瓶上安裝分餾柱,柱頂裝配150℃溫度計(jì),安裝分餾裝置。將圓底燒瓶用電熱套加熱,保持溫度在100~110c之間約60min,當(dāng)反應(yīng)生成的水及部分醋酸被蒸出時(shí),溫度計(jì)讀書(shū)會(huì)下降,表明反應(yīng)已經(jīng)完成,即可停止加熱。在攪拌下趁熱將反應(yīng)物倒入100ml冷水中,待完全冷卻析出結(jié)晶后,抽氣過(guò)濾,用冷水洗滌,即得粗乙酰苯胺。2.粗乙酰苯胺的精制將所得粗乙酰苯胺用50ml的水加熱煮沸,待油狀物完全溶解后(如不能完全溶解,可補(bǔ)加適量水并記錄加水體積),停止加熱,稍冷后加活性炭0.1g,攪拌,再繼續(xù)煮沸5~10min進(jìn)行脫色,趁熱過(guò)濾,過(guò)濾冷卻后有大量的晶體析出,再次抽濾,結(jié)晶用少量水洗滌2次,抽干,得精制的乙酰苯胺。稱(chēng)重,計(jì)算產(chǎn)率。六、實(shí)驗(yàn)結(jié)果及數(shù)據(jù)處理標(biāo)準(zhǔn)狀態(tài)下:冰醋酸用量:7.5ml產(chǎn)量:產(chǎn)率:各組結(jié)果: 第一組 第二組 第三組 第四組 第五組 第六組冰醋酸用量(ml) 4.5 6.5 7 7.5 8 8.5產(chǎn)量(g) 4.2 6.67 產(chǎn)率 分析部分一、實(shí)驗(yàn)結(jié)果分析蒸餾法分離的效率不高。只有被分離組分的沸點(diǎn)相差150攝氏度以上時(shí)才能充分分離。因此,分餾比蒸餾能夠得到較好的分離效果。二、注意事項(xiàng)1.反應(yīng)所用玻璃儀器必須干燥。2.久置的苯胺因?yàn)檠趸伾^深,會(huì)影響乙酰苯胺的質(zhì)量,故最好用新蒸的苯胺。3.加入少量鋅粉,是防止苯胺在反應(yīng)過(guò)程中氧化。4.反應(yīng)時(shí)蒸餾溫度不能太高,以免大量乙酸蒸出而降低產(chǎn)率。5.重結(jié)晶過(guò)程中,布氏漏斗和吸濾瓶一定要預(yù)熱。6.不可再沸騰的溶液中加入活性炭,以免引起暴沸。7.反映物冷卻后,固體產(chǎn)品立即析出,沾在瓶壁不容易理處。故須趁熱在攪動(dòng)下倒入冷水中,以祛除超過(guò)限量的醋酸及未效用的苯胺(它可成為苯胺醋酸鹽而溶于水)。8.趁熱過(guò)濾時(shí),也可采用抽濾裝置。但布氏漏斗和吸濾瓶一定要預(yù)熱。濾紙大小要適,抽濾過(guò)程要快,避免產(chǎn)品在布氏漏斗中結(jié)晶。9.冰醋酸具有強(qiáng)烈刺激性,要在通風(fēng)櫥內(nèi)取用。總結(jié):理論值與實(shí)際值往往相差很多,其中的系統(tǒng)誤差不可避免,但是隨機(jī)誤差是可以相對(duì)減少的;實(shí)驗(yàn)過(guò)程中由于操作不規(guī)范也會(huì)造成理論值與實(shí)驗(yàn)值的差距但是我們可以運(yùn)用控制變量法盡量減少實(shí)驗(yàn)誤差,從理論上說(shuō),控制變量的梯度越小的話應(yīng)該實(shí)驗(yàn)結(jié)果越精確。參考文獻(xiàn)“乙酰苯胺的制備論文”百度空間博文分享《有機(jī)化學(xué)實(shí)驗(yàn)》中國(guó)農(nóng)業(yè)出版社2007年7月第1版《胡宏紋有機(jī)化學(xué)》北京高等教育出版社2006年《有機(jī)化學(xué)學(xué)習(xí)指導(dǎo)》北京農(nóng)業(yè)大學(xué)出版社2006年
英文版Theacetanilidepreparation
Abstract:Microexperimentalconditionsacetanilidepreparedtoexplore,todeterminethebestconditionsforpreparationofmicro-experimentacetanilide.Byheatingthepreparationandpurificationmethodofdistillationandrecrystallization.ObtainhigheryieldACETANILIDE.Acetanilidepreparedmicro-experiments,theuseofsmalleramountsofreagentsandshortertimetoobtainasatisfactoryexperimentalresults.
Acetanilideismildanalgesicsandantipyretics,itoccupiesanimportantpositionintheOTCdrugs.InWorldWarII,whenalargenumberofusedchlorinemanufacturingacetamidobenzenesulfonyl.Acetanilideisalsousedthioacetamide.Inindustrialrubbervulcanizationacceleratoragent,fiberresincoatingstabilizer,hydrogenperoxidestabilizer,aswellasforsyntheticcamphor.Healthhazard:inhalationupperrespiratorytractirritant.High-doseintakecancausemethemoglobinemiaandbonemarrowhyperplasia.Repeatedexposurecanoccurcyanosis.Irritatingtotheskincancausedermatitis.Caninhibitthecentralnervoussystemandcardiovascularsystem,alargenumberofcontactmaycausedizzinessandpaleembolism.
Acetanilidebyacetylationofanilineandacetylchloride,acetylanhydrideoraceticacidreagentpreparedbythereaction.Themostintensereactionofacetylchloride,aceticanhydride,followedbyglacialaceticacidslowest.Acetanilidewithglacialaceticacidsystemtakeneedtobeheatedforalongtime,butthismethodismoreeconomical,commercialsignificance.Takingintoaccounttheexperimentalconditionsandeconomicfactors,thisexperimentwithglacialaceticacidispreparedbyacetanilide.(PreparationofAcetanilidemicroexperimentalconditionstoexplore,determineacetanilidebestconditionsforpreparationofmicro-experiment.Theuseofheatingandre-crystallizationmethodreturnpreparationandpurification.Ahigheryieldofacetanilide.Acetanilidepreparationofmicro-experiments,theuseofsmalleramountsofreagentsandshortertimetoobtainasatisfactoryexperimentalresults.)
Keywords:theacetaniliderecrystallization(acetanilide,recrystallization)ofglacialaceticacid(aceticacid)wasfilteredhot(hotfiltration)
Introduction:FormulaCH3COC6H4NH2,
MolecularWeight135.1652
CASNo.103-84-4
Properties:whiteshinyflakesorwhitecrystallinepowder.Combustible.Odorless.Stableintheair,neutral.Therelativedensityof1.2190(15/4°C).Themeltingpointof114.3°C.Theboilingpointof304°C.Flashpoint173.9°C.Spontaneouscombustionpointof546°C.Slightlysolubleinwater,solubleinhotwater,methanol,ethanol,ethylether,chloroform,acetone,glycerol,andbenzene.
Uses:pharmaceutical,dyes,rubbervulcanizationaccelerator,syntheticcamphor
Toxicity:intothebodybybreathinganddigestivesystem,caninhibitthecentralnervousandcardiovascularsystems,alargenumberofcontactmaycausedizzinessandpaleembolism.RatoralLD50of800mg/kg.Productionequipmentshouldbeclosed.Theoperatorshouldwearprotectiveequipment,toavoiddirectcontact.Withwarmwaterbathafterwork.
Packaging,storageandtransportation:innerplasticbag,outersacksorcanvasbag,netweight50kg.Storeinacool,dry,well-ventilatedplace,fire,moisture.Canbetransportedbycarortrain.Toxicchemicalsprovidesstorage.
Experimentalsection
First,thepurposeoftheexperiment:
1tomastertheprinciplesandmethodsofpreparationofacetanilide
2,tofurtherstudytherecrystallizationandpurificationmethodofoperationofthesolid
Second,theexperimentalprinciple:
Preparationofacetanilide,commonlyusedacetylationreagentglacialaceticacid,aceticanhydrideoracetylchloride,themostdramaticresponsewhentheacetylationreagent,followedbyaceticacid,glacialaceticacidandanilineistheslowest,butthereactionisstable,easytocontrol,cheaperandglacialaceticacid,theexperimentusedforaceticacidacetylationagent.
Acylationoftheamineplaysanimportantroleinorganicsynthesis.Asaprotectivemeasure,theprimaryandsecondaryarylaminesinorganicsynthesisusuallybeconvertedintotheiracetylderivativesinordertoreducethesensitivitydegradationoftheamineoxide,itdoesnotdestroythereactionreagent;reducedafteraminoacylationaminoelectrophilicsubstitutionreactions(especiallyhalogenated)activationcapacitytoclassIbythestrongpositioningbasetomoderate-intensityclassIpositioningbase,thereactionbecomesusefulfromdiversereplacesubstituted,oftenselectivelygeneratedduetothesterichindranceoftheacetylgroup,para-substituted.Withglacialaceticacidastheacylatingagentpreparedacetanilide.Thearylaminesavailabilitychloride,acidanhydrideorwithglacialaceticacidwasheatedtoacylation,usingglacialaceticacidreagentreadilyavailable,inexpensive,butrequirelongerreactiontimes,suitableforlarge-scaleprepared.Theacidanhydrideisgenerallybetterthanchlorideacylatingreagent.Acylationofthefreeaminewithpureaceticanhydride,isoftenaccompaniedbydiethylamide[ARN(COCH3)2]byproducts.Iftheacylationiscarriedoutinaceticacid-sodiumacetatebuffersolution,therateofhydrolysisduetotheacidanhydrideismuchslowerthantheacylationspeed,canbeaproductofhighpurity.However,thismethodisnotsuitablenitrobenzeneandotherweakalkalinearylamineacylation.
Thisreactionisareversiblereaction,theyieldislow,inordertoreducetheoccurrenceofthereversereactiontoobtainahighyield,toincreasetheamountofTitanium,alsotakethefractionationmethod,thecontroltemperatureofbetween105to110degrees,andcontinuouslyremovingthegeneratedwater,thebalanceismovedinthedirectionofpositivereactivity.Becauseoftheeasyoxidationofanilinebyaddingasmallamountofzincpowder,topreventtheoxidationofanilineinthereactionprocess.
ThepureAcetanilidewhiteflakycrystal,meltingpointof114degrees,slightlysolubleinwater,alcohol,ether,chloroform,acetoneandothersolvents,andinsolubleincoldwater,itcanbeusedhotwaterandrecrystallized.
Third,laboratoryequipmentandreagents:
1
apparatus:a50mLround-bottomedflask,50mLconicalflask,beaker,afractionatingcolumn,ahotbathfunnel,athermometerof150°C,suctionmeansset.
2reagent:aniline,glacialaceticacid,zincpowder,activatedcarbon.
Fourth,theexperimentaldevice:
Fractionationunithotfiltrationdevice
Filtrationdevice
V.Experimentalprocedure:
1acetanilidesynthesis
Add5mloffreshlydistilledanilineofof.7.5mlglacialaceticacidand0.1gofzincpowderina50mlround-bottomedflask.Thefractionationcolumn,thetopofthecolumnassemblyisinstalledinaround-bottomedflaskto150°Cthermometerinstallationfractionatingdevice.
Round-bottomedflaskwasheatedwithelectricsets,maintainingthetemperaturebetween100~110cofapproximately60minutes,whenthewaterofreactionandpartoftheaceticacidwasdistilledoff,athermometerreadingwilldecrease,indicatingthatthereactionhasbeencompleted,tostopheating.Understirringhotreactionwaspouredinto100mlofcoldwatertobecompletelyprecipitatedcrystalwascooled,suctionfiltered,washedwithcoldwater,i.e.theobtainedcrudeacetanilide.
2refiningofcrudeacetanilide
WilltheresultingcrudeACETANILIDEwith50mlofwaterheatedtoboilinguntiltheoiliscompletelydissolved(ifnotcompletelydissolved,complementplustheamountofwaterandrecordthevolumeofwaterwasadded),theheatingwasstopped,coolishaddactivatedcarbon0.1g,stirred,andthencontinueboiledfor5~10mindecolorized,filteredhot,filteredaftercooling,therearealargenumberofcrystals,againsuctionfilteredacetanilide,2timeswithasmallamountofwaterthatwaswashed,drained,waspurifiedbycrystallization.Weighedtocalculatetheyield.
Sixth,theexperimentalresults:
Understandardconditions:theamountofglacialaceticacid:7.5ml
Production:
Yield:
Eachsetofresults:
ThefifthgroupofsixthgroupoftheGroup1Group3Group4
Theamountofglacialaceticacid(ml)4.56.577.588.5
Yield(g)4.26.67
Yield
Analysissection
First,theexperimentalresultsofanalysis
Thedistillationseparationefficiencyisnothigh.Onlyfractionsboilingpointsdifferbymorethan150degreesCelsiustofullseparation.Accordingly,thefractionationdistillationtoobtainagoodseparationeffect.
Second,payattention
Thereactionglasswaremustbedried.
2thelonghomeanilineoxidationdarkercolor,willaffectthetheacetanilidequality,itisbesttousefreshlydistilledaniline.
3byaddingasmallamountofzincpowderistopreventtheoxidationofanilineinthereactionprocess.
4distillationtemperatureofthereactiontimecannotbetoohigh,inordertoavoidalotofaceticacidwasdistilledoffandreducetheyield.
5.RecrystallizationprocessinaBuchnerfunnelandsuctionflaskmustbepreheated.
6impossibilityboilingsolutionwasaddedactivatedcarbon,inordertoavoidbumping.
7reflectaftercooling,thesolidproductprecipitatedimmediatelystickinthewallofthebottleisnoteasytoManagementOffice.Thereforebehotintheagitationwaspouredintocoldwater,inordertogetridofaceticacidandnotlimitedutilityexceedsaniline(whichmaybecomeanilineacetatedissolved
Inwater).
Filteredhot,thesuctionmeansmayalsobeused.ButBuchnerfunnelandfilterflasktowarmup.Thesizeofthefilterpaper
Appropriatefiltrationprocessfaster,avoidtheproductcrystallizedinaBuchnerfunnel.
9.Glacialaceticacidisastrongirritanttoaccessinafumehood.
Summary:theoreticalandactualvalues??areoftenalotofdifference,systemerrorisinevitable,buttherandomerrorcanbereducedrelative;non-standardoperationcanalsocausethegapbetweenthetheoreticalandexperimentalvalues??oftheexperimentalprocessbutwecanusethecontrolvariableThemethodtominimizetheexperimentalerror,saidcontrolvariablegradientsmallerwordsshouldtheoreticallymoreaccurateexperimentalresult
ReferencesAcetanilidePreparationofpapers"BaiduSpaceblogposts
"ExperimentalOrganicChemistry"ChinaAgriculturePress,July2007
"TheHUHONGWENOrganicChemistryBeijingHigherEducationPress2006
OrganicChemistrystudyguideBeijingAgriculturalUniversityPress,2006謝謝?。。。。。。?!
魔力四射小組魔力四射生物代謝中酶的研究
Abstract:Theenzymeisoneofthesecurityconditionsofthebiologicalmetabolism,playacatalyticroleofbiochemicalreactionsinthethebiologicalmetabolismprocess,inordertoensurethesmoothprogressofmetabolismenzymecatalysisefficiencycharacteristics,roducestheroleofenzymesinbiologicalmetabolism,aswellasthecharacteristicsoftheenzymeanditsproofexperiment.
摘要:酶是生物新陳代謝的保障條件之一,在生物的新陳代謝過(guò)程中,主要起到催化生物化學(xué)反應(yīng)的作用,從而保證新陳代謝順利進(jìn)行.酶的催化作用具有高效性的特點(diǎn),而這一特性又取決于酶的高效催化機(jī)理。本文主要介紹了酶在生物代謝中的作用,以及酶的特性和其證明實(shí)驗(yàn)。
Keywords:enzymebiochemicalcharacteristicsoftheenzymebiologicalmetabolism
Introduction:enzymesensureorderlyconductofbiochemicalreactionsinvivoalmostallchemicalreactionsarecarriedoutundertheefficientcatalysisoftheenzyme.Butindifferentcircumstancesenzymesasbiologicalcatalysts,theircatalyticactivitybymanyfactors,suchastemperature,pHvalue,organicsolvents,heavymetalions,enzymeconcentration,enzymeactivators,inhibitors,etc.,differenttypesofenzymestheoccurrenceofdifferentcatalyticreactions,buttheseareourlives.
關(guān)鍵詞:酶生物化學(xué)酶的特性生物代謝引言:酶是保證生物化學(xué)反應(yīng)有序進(jìn)行的因素,生物體內(nèi)幾乎所有的化學(xué)反應(yīng)都是在酶的高效催化作用下進(jìn)行的。但是在不同的環(huán)境下酶作為生物催化劑,其催化活性受到很多因素的影響,如溫度、pH值、有機(jī)溶劑、重金屬離子、酶濃度、酶的激活劑、抑制劑等等,不同種類(lèi)的酶會(huì)發(fā)生不同的催化反應(yīng),然而這些都與我們的生活息息相關(guān)。
Body:Asearlyas8000yearsago,theChinesepeoplehavebeguntouseoforganismsenzyme(crudeenzymepreparation)theproductionoffood,treatmentofdisease.In1773,ItalianscientistsSpallanzani,designedaningeniousexperiment,thefilletintosmallmetalcage,thenEagleswallow,overtimehewillremovethedumplings,foundthatthemeatisgone.Sohespeculatedthatthegastricjuicecontainingcertainsubstancestodigestmeat,butwhathedidnotfind.In1878,Khnefirstproposedthe"gratitudeoftheenzyme,andtheenzymeUniformNamingEnzyme(Greek,meaning"inyeast").
1926Sumnenfromtheconcanavalinseedinextractedoutofthecrystallizationofurease,andprovedanenzymethatcatalyzestheureamoleculesintoammoniaandcarbondioxide,thefirsttodemonstratethatureaseisaprotein.Enzymes,earlyinyeastinyeastinyeastmeanabiologicalcatalystgeneratedbythebiologicallivingcellsinthebody,themajoritymadeupofprotein,afewforRNA.Underverymildconditionsinthebody,high-efficiencycatalyticvarietyofbiochemicalreactions.Promotethemetabolismoforganisms,lifeactivitiesdigestion,absorption,breathing,functioningandreproductiveenzymaticintothereactionprocess.
1926Sumnenfromtheconcanavalinseedinextractedoutofthecrystallizationofurease,andprovedanenzymethatcatalyzestheureamoleculesintoammoniaandcarbondioxide,thefirsttodemonstratethatureaseisaprotein.Enzymes,earlyinyeastinyeastinyeastmeanabiologicalcatalystgeneratedbythebiologicallivingcellsinthebody,themajoritymadeupofprotein,afewforRNA.Underverymildconditionsinthebody,high-efficiencycatalyticvarietyofbiochemicalreactions.Promotethemetabolismoforganisms,lifeactivitiesdigestion,absorption,breathing,functioningandreproductiveenzymaticintothereactionprocess.
ThentakenABoftwotesttubes,testtubesAAdd1mlofsucrosesolutionwasadded1mlofthestarchsolutioninthetesttubeB,wereaddedtoanequalamountofsalivaamylase1ml,filmreagentaddinganequalamountofthetwotubes,waterbath,theexperimentalresultsoftesttubeAcolortesttubeBbrickredprecipitate.Descriptionofstarchbysalivaryamylasedecomposedintoreducingsugars,sucroseisnotdecomposed.Thisshowsthattheenzymehasspecificity.
TakeA,(B)twocrystallizationofthetesttube,wereinjectedinto3mlofapaste,then,thethedimetoriseto2mloffreshwheatamylasefiltrateinjectioninaformertesttube,injectiondimetorisetotwomlofwaterinatesttubeacetateascontrol.Oscillationtwotesttubes,thelowerhalfofA,Btwotesttubes,soakedinwarmwaterof15degreesCelsius,heatforaboutfiveminutes,andthenremovethetwotesttubes,respectivelydropofiodinesolution.Aceticvitropasteintoblue,andpastewithinthearmortubedoesnotbecomeblue.
Encounteriodinesolutionbecomesblue,whichischaracteristicofstarch.PasteinthecaseofiodinesolutioninthetesttubeAconstantblue,indicatingthatthestarchwithinthearmortubehasbeentransformedintoothersubstances.Itselfdoesnotchange.Enzymeisoneoftheconditionsoftheprotectionofthebiologicalmetabolism,playacatalyticroleofbiochemicalreactionsinthethebiologicalmetabolismprocess,soastoensurethesmoothrunningofthemetabolicenzymecatalysisefficiencyfeatures,thisfeaturedependsonefficientcatalyticmechanismoftheenzyme,theenzymeincellmetabolismplayacatalyticrole,isacatalyst.
Encounteriodinesolutionbecomesblue,whichischaracteristicofstarch.PasteinthecaseofiodinesolutioninthetesttubeAconstantblue,indicatingthatthestarchwithinthearmortubehasbeentransformedintoothersubstances.Itselfdoesnotchange.Enzymeisoneoftheconditionsoftheprotectionofthebiologicalmetabolism,playacatalyticroleofbiochemicalreactionsinthethebiologicalmetabolismprocess,soastoensurethesmoothrunningofthemetabolicenzymecatalysisefficiencyfeatures,thisfeaturedependsonefficientcatalyticmechanismoftheenzyme,theenzymeincellmetabolismplayacatalyticrole,isacatalyst.
Anenzymeasacatalyst,varioussubstancescancatalyzethedecomposition,butalsocanpromotethesynthesisofcertainsubstances,suchasproteinsynthesis,thesynthesisoffat,etc.Thus,wesaythatithastheroleofchemical.Inadditiontothenucleicacidenzyme,otherenzymesareproteins,whiletheproteinistranslatedfromthegeneticmaterialDNAbytranscription,i.e.,DNAistranscribedintomRNAandthentranslatedintoaproteinfrommRNA,thegeneticmaterialisproteinexpressionwithchemicalandGeneticdualregulatoryrole.Thereasonwhythemajorityofcellmetabolismenzymeisabiologicalcatalystbecausetheenzymesgeneratedbytheinvivocells.Composedofprotein(asmallnumberofRNA).Avarietyofbiochemicalreactionsunderverymildconditionsinthebody,high-efficiencycatalyticpromotethemetabolismoftheorganism.Lifeactivitiesofdigestion,absorption,respiration,movementandreproductionareenzymaticreactionprocess.
Theenzymeisthebasisforthesurvivalofthecells.Cellmetabolismincludingalmostallchemicalreactionsarecarriedoutunderthecatalysisoftheenzyme.Suchasmammaliancellscontainthousandsofenzymes.Eitherdissolvedinthecytosol,ortogetherwithavarietyofmembranestructure,orotherstructureswithinthecellsonaspecificlocation.Theseenzymesarecollectivelyreferredtoastheintracellularenzyme;Also,therearesynthesizedwithinthecellandthensecretedintotheextracellularenzyme-extracellularenzymes.Theabilityoftheenzyme-catalyzedchemicalreactioncalledenzymeactivity(oractivity).Theenzymeactivitycanbeaffectedbymanyfactorsregulatingcontrol,sothatthethebiologicalphysicalabilitytoadapttochangesintheexternalconditions,tomaintainthelife.
Withouttheparticipationofenzymes,metabolismonlyatanextremelyslowrate,theactivitiesoflifecannotmaintain.Forexample,thefoodmustbedroppedintheactionoftheenzymesolutionintosmallmoleculescanthroughtheintestinalwall,tissueabsorptionandutilization.Pepsininthestomach,pancreaticsecretorytrypsin,chymotrypsin,lipaseandamylaseenzymesintheintestinal.Anotherexampleistheoxidationofthefoodisanimalsourceofenergy,theoxidationprocessiscompletedinaseriesofenzymecatalyzed.Cellmetabolismincludingalmostallchemicalreactionsarecarriedoutunderthecatalysisoftheenzyme.Theenzymeactivitycanbeaffectedbymanyfactorsregulatingcontrol,sothatthethebiologicalphysicalabilitytoadapttochangesintheexternalconditions,tomaintainthelife.
Withouttheparticipationofenzymes,metabolismonlyatanextremelyslowrate,theactivitiesoflifecannotmaintain.Somostofthecellsinvivometabolicenzymescannotleave.Theenzymereactionisdifferentunderdifferentconditions,e.g.,normalhumanbodytemperatureis37°C,thetemperaturewasraisedto38°C,althoughthetemperatureisjusta1°Crise,butdidnotfeelveryspiritraisedto39°C.even40°C,andpersistenthighfever,therewillbeaseriesofseverereactions,suchasdrowsiness,coma,convulsions,evenlife-threatening,thisisbecausetheenzymeasabiologicalcatalyst,itscatalyticactivitybymanyfactors,suchastemperature,pHvalue,organicsolvents,heavymetalions,enzymeconcentration,enzymeactivators,inhibitors,etc.,andtheenzymeactivityofthesefactorsisverysensitivetosmallchangesinfluencingfactors,enzymeactivityoccursveryGreatchange.
Theoptimumtemperatureoftheenzymeinthebodygenerallyas37°C,whenthebodytemperatureaboveorbelowthistemperature,thebodywillgreatlyreducetheenzymeactivityinavarietyofbiochemicalreactionswithinthecellscannotbenormal.Thecatalyticactionoftheenzymeisgreatlyaffectedbytemperature,ontheonehand,andthegeneralchemicalreaction,elevatedtemperaturesmayincreasethespeedoftheenzymaticreaction.Usuallythetemperatureisincreasedto10℃,reactiontimesfaster,thefinalreactionratereachesitsmaximumvalue.Theotherhand,thechemicalnatureoftheenzymeisaprotein,thetemperatureistoohighcancauseproteindenaturation,resultingininactivationoftheenzyme.Thus,thereactionratereachesamaximumasthetemperaturerises,thereactionratebutgraduallydecreasedorevencompletelystopthereaction.
Whenthereactionratereachesamaximumtemperaturereferredtoastheroleofcertainenzymeoptimumtemperature.Higherorlowerthantheoptimumtemperature,thereactionrateisgraduallyreduced.Themostanimalsenzyme-passtemperatureof37°Cfora40°Candtheplantenzymeoptimumtemperatureof50°Cfora60°C.However,theoptimumtemperatureofanenzymeisnotcompletelyfixed,itistheroleofthetimelength,thereactiontimeincreased,theoptimumtemperaturetolowervalues??inthedirectionofmovement.Whentheenzymeactivityisusuallymeasuredattheoptimumtemperatureoftheenzymereaction.Inordertomaintainaconstanttemperatureduringthereaction,usuallyusingathermostaticdevicesuchasathermostatwaterbath.
Ofcourse,theenzymeactivityisrelatedwiththetemperature,pH,isalsoaffectedbytheimpactoforganicsolvents,heavymetalions,suchas.Organicsolventsandheavymetalionsaffecttheactivityofthemainreasonisthatcertainchemicalgroupsinorganicsolventsandheavymetalionsontheenzymeproteinbinding,completelossofactivityoftheenzyme,whichisalsoingestedorganophosphoruspesticides,organochlorinepesticidesorheavymetalionsfromfoodpoisoningoreventhecauseofdeath.Milkandsoymilkcontainsalotofproteins,theseproteinscanbecombinedwithheavymetalsororganics,leavingthesemetalionsandorganicmatterisprecipitated.Drinkalotofmilkorsoymilkwheneatingfoodcontainingheavymetalsorpesticides,thesetoxicsubstancescansettledownisnotabsorbedbythedigestivetract
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