乙酰苯胺的制備(曹正強(qiáng)教授)

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?？扇肌o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。用汽車或火車運(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姿帷⒋姿狒蛞阴Ｂ鹊?，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?；噭?。胺的酰化在有機(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?；苌镆越档桶穼?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類定位基變?yōu)橹械葟?qiáng)度的第Ⅰ類定位基，使反應(yīng)由多元取代變?yōu)橛杏玫囊辉〈?，由于乙酰基的空間位阻,往往選擇性的生成對(duì)位取代物。用冰醋酸為酰化劑制備乙酰苯胺。芳胺可用酰氯、酸酐或與冰醋酸加熱來進(jìn)行?；?，使用冰醋酸試劑易得，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。酸酐一般來說是比酰氯更好的?；噭Ｓ糜坞x胺與純乙酸酐進(jìn)行?；瘯r(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?；捎谒狒乃馑俣缺弱；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酰化。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，趁熱過濾，過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?？偨Y(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，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