乙酰苯胺的制备(曹正强教授)

魔力四射绿色化学

奋斗拼搏乙酰苯胺的制备摘要：对乙酰苯胺制备的微型实验条件进行探讨，确定乙酰苯胺制备微型实验的最佳条件。利用加热蒸馏和重结晶法进行制备和提纯。获得较高产率的乙酰苯胺。乙酰苯胺制备的微型实验，利用较少量的试剂和较短的时间获得了满意的实验效果。乙酰苯胺是温和的止痛药和退热药，它在OTC药物中占有重要地位。在第二次世界大战的时候大量用于制造对乙酰氨基苯磺酰氯。乙酰苯胺也用于制硫代乙酰胺。在工业上可作橡胶硫化促进剂、纤维脂涂料的稳定剂、过氧化氢的稳定剂，以及用于合成樟脑等。健康危害：吸入对上呼吸道有刺激性。高剂量摄入可引起高铁血红蛋白血症和骨髓增生。反复接触可发生紫绀。对皮肤有刺激性，可致皮炎。能抑制中枢神经系统和心血管系统，大量接触会引起头昏和面色苍白等症。乙酰苯胺可以通过苯胺与乙酰氯、乙酰酐或者冰醋酸等试剂进行乙酰化反应制得。其中乙酰氯反应最剧烈，乙酸酐次之，冰醋酸最慢。虽然用冰醋酸制取乙酰苯胺需要长时间加热，但此方法比较经济，有商业意义。考虑到实验条件和经济因素，这个实验用冰醋酸来制取乙酰苯胺。Abstrate:PreparationofAcetanilidemicroexperimentalconditionstoexplore,determineacetanilidebestconditionsforpreparationofmicro-experiment.Theuseofheatingandre-crystallizationmethodreturnpreparationandpurification.Ahigheryieldofacetanilide.Acetanilidepreparationofmicro-experiments,theuseofsmalleramountsofreagentsandshortertimetoobtainasatisfactoryexperimentalresults.关键词：乙酰苯胺重结晶（acetanilide,recrystallization）冰醋酸（aceticacid）热过滤（hotfiltration）前言：分子式CH3COC6H4NH2,分子量135.1652CAS号103-84-4性质:白色有光泽片状结晶或白色结晶粉末。可燃。无臭。在空气中稳定，呈中性。相对密度1.2190(15/4℃)。熔点114.3℃。沸点304℃。闪点173.9℃。自燃点546℃。微溶于冷水，溶于热水、甲醇、乙醇、乙醚、氯仿、丙酮、甘油和苯等。用途:制药、染料、橡胶硫化促进剂、合成樟脑等毒性:由呼吸和消化系统进入体内，能抑制中枢神经系统和心血管系统，大量接触会引起头昏和面色苍白等症。大鼠经口LD50为800mg/kg。生产设备应密闭。操作人员应穿戴好防护用具，避免直接接触。下班后用温水沐浴。包装储运:采用内层塑料袋、外层麻袋或帆布袋包装，每袋净重50kg。贮存在阴凉、干燥、通风处，防火、防潮。用汽车或火车运输均可。按有毒化学品规定贮运。实验部分一、实验目的:1、掌握制备乙酰苯胺的原理和方法2、进一步学习重结晶和纯化固体的操作方法二、实验原理：:制备乙酰苯胺时，常用的乙酰化试剂有冰醋酸、醋酸酐或乙酰氯等，当采用乙酰化试剂时反应最剧烈，醋酸次之，冰醋酸与苯胺反应最慢，但反应平稳、易于控制，且冰醋酸价格较便宜，故本实验采用冰醋酸作乙酰化试剂。胺的酰化在有机合成中有着重要的作用。作为一种保护措施，一级和二级芳胺在合成中通常被转化为它们的乙酰基衍生物以降低胺对氧化降解的敏感性，使其不被反应试剂破坏；同时氨基酰化后降低了氨基在亲电取代反应（特别是卤化）中的活化能力，使其由很强的第Ⅰ类定位基变为中等强度的第Ⅰ类定位基，使反应由多元取代变为有用的一元取代，由于乙酰基的空间位阻,往往选择性的生成对位取代物。用冰醋酸为酰化剂制备乙酰苯胺。芳胺可用酰氯、酸酐或与冰醋酸加热来进行酰化，使用冰醋酸试剂易得，价格便宜，但需要较长的反应时间，适合于规模较大的制备。酸酐一般来说是比酰氯更好的酰化试剂。用游离胺与纯乙酸酐进行酰化时，常伴有二乙酰胺[ArN(COCH3)2]副产物的生成。但如果在醋酸-醋酸钠的缓冲溶液中进行酰化，由于酸酐的水解速度比酰化速度慢得多，可以得到高纯度的产物。但这一方法不适合于硝基苯和其它碱性很弱的芳胺的酰化。该反应是可逆反应，产率较低，为减少逆反应的发生，得到较高的收率，可增加乙酸的用量，另外还采取分馏法，控制温度在105到110度之间，不断除去生成的水，有效地使平衡向正反应方向移动。由于苯胺易氧化，加入少量锌粉，防止苯胺在反应过程中氧化。纯乙酰苯胺为白色片状结晶，熔点为114度，稍溶于热水、乙醇、乙醚、氯仿、丙酮等溶剂，而难溶于冷水，故可用热水进行重结晶。三、实验仪器与试剂：1仪器：50mL圆底烧瓶、50mL锥形瓶、烧杯、分馏柱、热浴漏斗、150℃温度计、抽滤装置一套。2试剂：苯胺、冰醋酸、锌粉、活性炭。四、实验装置：(1)分馏装置(2)热过滤装置(3)抽滤装置五、实验步骤1.乙酰苯胺的合成在50ml圆底烧瓶中加入5ml新蒸馏的苯胺.7.5ml冰醋酸和0.1g锌粉。在圆底烧瓶上安装分馏柱，柱顶装配150℃温度计，安装分馏装置。将圆底烧瓶用电热套加热，保持温度在100~110c之间约60min，当反应生成的水及部分醋酸被蒸出时，温度计读书会下降，表明反应已经完成，即可停止加热。在搅拌下趁热将反应物倒入100ml冷水中，待完全冷却析出结晶后，抽气过滤，用冷水洗涤，即得粗乙酰苯胺。2.粗乙酰苯胺的精制将所得粗乙酰苯胺用50ml的水加热煮沸，待油状物完全溶解后（如不能完全溶解，可补加适量水并记录加水体积），停止加热，稍冷后加活性炭0.1g,搅拌，再继续煮沸5~10min进行脱色，趁热过滤，过滤冷却后有大量的晶体析出，再次抽滤，结晶用少量水洗涤2次，抽干，得精制的乙酰苯胺。称重，计算产率。六、实验结果及数据处理标准状态下：冰醋酸用量：7.5ml产量：产率：各组结果： 第一组 第二组 第三组 第四组 第五组 第六组冰醋酸用量（ml） 4.5 6.5 7 7.5 8 8.5产量（g） 4.2 6.67 产率 分析部分一、实验结果分析蒸馏法分离的效率不高。只有被分离组分的沸点相差150摄氏度以上时才能充分分离。因此，分馏比蒸馏能够得到较好的分离效果。二、注意事项1.反应所用玻璃仪器必须干燥。2.久置的苯胺因为氧化而颜色较深，会影响乙酰苯胺的质量，故最好用新蒸的苯胺。3.加入少量锌粉，是防止苯胺在反应过程中氧化。4.反应时蒸馏温度不能太高，以免大量乙酸蒸出而降低产率。5.重结晶过程中，布氏漏斗和吸滤瓶一定要预热。6.不可再沸腾的溶液中加入活性炭，以免引起暴沸。7.反映物冷却后，固体产品立即析出，沾在瓶壁不容易理处。故须趁热在搅动下倒入冷水中，以祛除超过限量的醋酸及未效用的苯胺（它可成为苯胺醋酸盐而溶于水）。8.趁热过滤时，也可采用抽滤装置。但布氏漏斗和吸滤瓶一定要预热。滤纸大小要适，抽滤过程要快，避免产品在布氏漏斗中结晶。9.冰醋酸具有强烈刺激性，要在通风橱内取用。总结：理论值与实际值往往相差很多，其中的系统误差不可避免，但是随机误差是可以相对减少的；实验过程中由于操作不规范也会造成理论值与实验值的差距但是我们可以运用控制变量法尽量减少实验误差，从理论上说，控制变量的梯度越小的话应该实验结果越精确。参考文献“乙酰苯胺的制备论文”百度空间博文分享《有机化学实验》中国农业出版社2007年7月第1版《胡宏纹有机化学》北京高等教育出版社2006年《有机化学学习指导》北京农业大学出版社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谢谢！！！！！！！！

魔力四射小组魔力四射生物代谢中酶的研究

Abstract:Theenzymeisoneofthesecurityconditionsofthebiologicalmetabolism,playacatalyticroleofbiochemicalreactionsinthethebiologicalmetabolismprocess,inordertoensurethesmoothprogressofmetabolismenzymecatalysisefficiencycharacteristics,roducestheroleofenzymesinbiologicalmetabolism,aswellasthecharacteristicsoftheenzymeanditsproofexperiment.

摘要：酶是生物新陈代谢的保障条件之一,在生物的新陈代谢过程中,主要起到催化生物化学反应的作用,从而保证新陈代谢顺利进行.酶的催化作用具有高效性的特点,而这一特性又取决于酶的高效催化机理。本文主要介绍了酶在生物代谢中的作用，以及酶的特性和其证明实验。

Keywords:enzymebiochemicalcharacteristicsoftheenzymebiologicalmetabolism

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

关键词：酶生物化学酶的特性生物代谢引言:酶是保证生物化学反应有序进行的因素，生物体内几乎所有的化学反应都是在酶的高效催化作用下进行的。但是在不同的环境下酶作为生物催化剂，其催化活性受到很多因素的影响，如温度、pH值、有机溶剂、重金属离子、酶浓度、酶的激活剂、抑制剂等等，不同种类的酶会发生不同的催化反应，然而这些都与我们的生活息息相关。

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