乙酰苯胺的制備(曹正強教授)

魔力四射綠色化學

奮斗拼搏乙酰苯胺的制備摘要：對乙酰苯胺制備的微型實驗條件進行探討，確定乙酰苯胺制備微型實驗的最佳條件。利用加熱蒸餾和重結晶法進行制備和提純。獲得較高產率的乙酰苯胺。乙酰苯胺制備的微型實驗，利用較少量的試劑和較短的時間獲得了滿意的實驗效果。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)的時候大量用于制造對乙酰氨基苯磺酰氯。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。反復接觸可發(fā)生紫紺。對皮膚有刺激性，可致皮炎。能抑制中樞神經系統(tǒng)和心血管系統(tǒng)，大量接觸會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行乙?；磻频?。其中乙酰氯反應最劇烈，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時間加熱，但此方法比較經濟，有商業(yè)意義。考慮到實驗條件和經濟因素，這個實驗用冰醋酸來制取乙酰苯胺。Abstrate:PreparationofAcetanilidemicroexperimentalconditionstoexplore,determineacetanilidebestconditionsforpreparationofmicro-experiment.Theuseofheatingandre-crystallizationmethodreturnpreparationandpurification.Ahigheryieldofacetanilide.Acetanilidepreparationofmicro-experiments,theuseofsmalleramountsofreagentsandshortertimetoobtainasatisfactoryexperimentalresults.關鍵詞：乙酰苯胺重結晶（acetanilide,recrystallization）冰醋酸（aceticacid）熱過濾（hotfiltration）前言：分子式CH3COC6H4NH2,分子量135.1652CAS號103-84-4性質:白色有光澤片狀結晶或白色結晶粉末?？扇?。無臭。在空氣中穩(wěn)定，呈中性。相對密度1.2190(15/4℃)。熔點114.3℃。沸點304℃。閃點173.9℃。自燃點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、橡膠硫化促進劑、合成樟腦等毒性:由呼吸和消化系統(tǒng)進入體內，能抑制中樞神經系統(tǒng)和心血管系統(tǒng)，大量接觸會引起頭昏和面色蒼白等癥。大鼠經口LD50為800mg/kg。生產設備應密閉。操作人員應穿戴好防護用具，避免直接接觸。下班后用溫水沐浴。包裝儲運:采用內層塑料袋、外層麻袋或帆布袋包裝，每袋凈重50kg。貯存在陰涼、干燥、通風處，防火、防潮。用汽車或火車運輸均可。按有毒化學品規(guī)定貯運。實驗部分一、實驗目的:1、掌握制備乙酰苯胺的原理和方法2、進一步學習重結晶和純化固體的操作方法二、實驗原理：:制備乙酰苯胺時，常用的乙?；噭┯斜姿帷⒋姿狒蛞阴Ｂ鹊?，當采用乙酰化試劑時反應最劇烈，醋酸次之，冰醋酸與苯胺反應最慢，但反應平穩(wěn)、易于控制，且冰醋酸價格較便宜，故本實驗采用冰醋酸作乙酰化試劑。胺的?；谟袡C合成中有著重要的作用。作為一種保護措施，一級和二級芳胺在合成中通常被轉化為它們的乙?；苌镆越档桶穼ρ趸到獾拿舾行?，使其不被反應試劑破壞；同時氨基酰化后降低了氨基在親電取代反應（特別是鹵化）中的活化能力，使其由很強的第Ⅰ類定位基變?yōu)橹械葟姸鹊牡冖耦惗ㄎ换狗磻啥嘣〈優(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位取代物。用冰醋酸為?；瘎┲苽湟阴１桨?。芳胺可用酰氯、酸酐或與冰醋酸加熱來進行?；?，使用冰醋酸試劑易得，價格便宜，但需要較長的反應時間，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?。用游離胺與純乙酸酐進行酰化時，常伴有二乙酰胺[ArN(COCH3)2]副產物的生成。但如果在醋酸-醋酸鈉的緩沖溶液中進行?；捎谒狒乃馑俣缺弱；俣嚷枚?，可以得到高純度的產物。但這一方法不適合于硝基苯和其它堿性很弱的芳胺的?；Ｔ摲磻强赡娣磻?，產率較低，為減少逆反應的發(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方向移動。由于苯胺易氧化，加入少量鋅粉，防止苯胺在反應過程中氧化。純乙酰苯胺為白色片狀結晶，熔點為114度，稍溶于熱水、乙醇、乙醚、氯仿、丙酮等溶劑，而難溶于冷水，故可用熱水進行重結晶。三、實驗儀器與試劑：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、抽濾裝置一套。2試劑：苯胺、冰醋酸、鋅粉、活性炭。四、實驗裝置：(1)分餾裝置(2)熱過濾裝置(3)抽濾裝置五、實驗步驟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，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，當反應生成的水及部分醋酸被蒸出時，溫度計讀書會下降，表明反應已經完成，即可停止加熱。在攪拌下趁熱將反應物倒入100ml冷水中，待完全冷卻析出結晶后，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，結晶用少量水洗滌2次，抽干，得精制的乙酰苯胺。稱重，計算產率。六、實驗結果及數(shù)據(jù)處理標準狀態(tài)下：冰醋酸用量：7.5ml產量：產率：各組結果： 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產量（g） 4.2 6.67 產率 分析部分一、實驗結果分析蒸餾法分離的效率不高。只有被分離組分的沸點相差150攝氏度以上時才能充分分離。因此，分餾比蒸餾能夠得到較好的分離效果。二、注意事項1.反應所用玻璃儀器必須干燥。2.久置的苯胺因為氧化而顏色較深，會影響乙酰苯胺的質量，故最好用新蒸的苯胺。3.加入少量鋅粉，是防止苯胺在反應過程中氧化。4.反應時蒸餾溫度不能太高，以免大量乙酸蒸出而降低產率。5.重結晶過程中，布氏漏斗和吸濾瓶一定要預熱。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，固體產品立即析出，沾在瓶壁不容易理處。故須趁熱在攪動下倒入冷水中，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，也可采用抽濾裝置。但布氏漏斗和吸濾瓶一定要預熱。濾紙大小要適，抽濾過程要快，避免產品在布氏漏斗中結晶。9.冰醋酸具有強烈刺激性，要在通風櫥內取用?？偨Y：理論值與實際值往往相差很多，其中的系統(tǒng)誤差不可避免，但是隨機誤差是可以相對減少的；實驗過程中由于操作不規(guī)范也會造成理論值與實驗值的差距但是我們可以運用控制變量法盡量減少實驗誤差，從理論上說，控制變量的梯度越小的話應該實驗結果越精確。參考文獻“乙酰苯胺的制備論文”百度空間博文分享《有機化學實驗》中國農業(yè)出版社2007年7月第1版《胡宏紋有機化學》北京高等教育出版社2006年《有機化學學習指導》北京農業(yè)大學出版社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反應的作用,從而保證新陳代謝順利進行.酶的催化作用具有高效性的特點,而這一特性又取決于酶的高效催化機理。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驗。

Keywords:enzymebiochemicalcharacteristicsoftheenzymebiologicalmetabolism

Introduction:enzymesensureorderlyconductofbiochemicalreactionsinvivoalmostallchemicalreactionsarecarriedoutundertheefficientcatalysisoftheenzyme.Butindifferentcircumstancesenzymesasbiologicalcatalysts,theircatalyticactivitybymanyfactors,suchastemperature,pHvalue,organicsolvents,heavymetalions,enzymeconcentration,enzymeactivators,inhibitors,etc.,differenttypesofenzymestheoccurrenceofdifferentcatalyticreactions,buttheseareourlives.

關鍵詞：酶生物化學酶的特性生物代謝引言:酶是保證生物化學反應有序進行的因素，生物體內幾乎所有的化學反應都是在酶的高效催化作用下進行的。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，不同種類的酶會發(fā)生不同的催化反應，然而這些都與我們的生活息息相關。

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