制藥工程專業(yè)英語第6單元

1、PART2BIOCHEMICALPHARMACEUTICALSUnit6IsolationofCaffeinefromTeaInthisexperiment，Caffeinewillbeisolatedfromtealeaves.Themajorproblemoftheisolationisthatcaffeinedoesnotoccuraloneintealeaves，butisaccompaniedbyothernaturalsubstancesfromwhichitmustbeseparated.Themajorcomponentoftealeavesiscellulose，whichi

2、sthemajorstructuralmaterialofallplantcells.Celluloseisapolymerofglucose.Sincecelluloseisvirtuallyinsolubleinwater，itpresentsnoproblemsintheisolationprocedure.Caffeine，ontheotherhand，iswatersolubleandisoneofthemajorsubstancesextractedintothesolutioncalledtea.”Caffeinecomprisesasmuchasp5ercentbyweight

3、oftheleafmaterialinteaplants.Tanninsalsodissolveinthehotwaterusedtoextracttealeaves.Thetermtannindoesnotrefertoasinglehomogeneouscompound，oreventosubstanceswhichhavesimilarchemicalstructure.Itreferstoaclassofcompoundswhichhavecertainpropertiesincommon.Tanninsarephenoliccompoundshavingmolecularweight

4、sbetween500and3000.Theyarewidelyusedtotan”leatheTrh.eyprecipitatealkaloidszandproteinsfromaqueoussolutions.Tanninsareusuallydividedintotwoclasses:thosewhichcanbehydrolyzedandthosewhichcannot.Tanninsofthefirsttypewhicharefoundinteagenerallyyieldglucoseandgallicacidwhentheyarehydrolyzed.Thesetanninsar

5、eestersofgallicacidandglucose.Theyrepresentstructuresinwhichsomeofthehydroxylgroupsinglucosehavebeenesterifiedbydigalloylgroups.Thenon-hydrolyzabletanninsfoundinteaarecondensationpolymersofcatechin.Thesepolymersarenotuniforminstructure，butcatechinmoleculesareusuallylinkedtogetheratringpositions4and8

6、.Whentanninsareextractedintohotwater，thehydrolyzableonesarepartiallyhydrolyzed，meaningthatfreegallicacidisalsofoundintea.Thetannins，byvirtueoftheirphenolicgroups，andgallicacidbyvirtueofitscarboxylgroups，arebothacidic.Ifcalciumcarbonate，abase，isaddedtoteawater，thecalciumsaltsoftheseacidsareformed.Caf

7、feinecanbeextractedfromthebasicteasolutionwithchloroform，butthecalciumsaltsofgallicacidandthetanninsarenotchloroformsolubleandremainbehindintheaqueoussolution.Thebrowncolorofateasolutionisduetoflavonoidpigmentsandchlorophylls，aswellastheirrespectiveoxidationproducts.Althoughchlorophyllsaresomewhatch

8、loroformsoluble，mostoftheothersubstancesinteaarenot.Thus，thechloroformextractionofthebasicteasolutionremovesnearlypurecaffeine.Thechloroformiseasilyremovedbydistillation(by61C)toleavethecrudecaffeine.Thecaffeinemaybepurifiedbyrecrystallizationorbysublimation.68CatechinGallicAcidInasecondpartofthisex

9、periment，Caffeinewillbeconvertedtoaderivative.Aderivativeofacompoundisasecondcompound，ofknownmeltingpoint，formedfromtheoriginalcompoundbyasimplechemicalreaction.Intryingtomakeapositiveidentificationofanorganiccompound，itisoftencustomarytoconvertitintoaderivative.Ifthefirstcompound，Caffeineinthiscase

10、，anditsderivativebothhavemeltingpointswhichmatchthosereportedinthechemicalliterature(e.g.，ahandbook)，itisassumedthatthereisnocoincidenceandthattheidentityofthefirstcompound，Caffeine，hasbeendefinitelyestablished.Caffeineisabaseandwillreactwithanacidtogiveasalt.Usingsalicylicacid，aderivativesaltofCaff

11、eine，Caffeinesalicylate，willbemadeinordertoestablishtheidentityoftheCaffeineisolatedfromtealeaves.SpecialInstructionsBecarefulwhenhandlingchloroform.Itisatoxicsolvent，andyoushouldnotbreatheitexcessivelyorspillitonyourself.Whendiscardingspenttealeaves，donotputtheminthesinkbecausetheywillclogthedrain.

12、Disposeoftheminawastecontainer.ProcedurePlace25gofdrytealeaves，25gofcalciumcarbonatepowder，and250mlofwaterina500mlthreeneckroundbottomflaskequippedwithacondenserforreflux.Stoppertheunusedopeningsintheflaskandheatthemixtureunderrefluxforabout20minutes.UseaBunsenburnertoheat.Whilethesolutionisstillhot

13、，filteritbygravitythroughaflutedfilterusingafastfilterpapersuchasE&DNo.617orS&SNo.595.Youmayneedtochangethefilterpaperifitclogs.Coolthefiltrate(filteredliquid)toroomtemperatureand，usingaseparatoryfunnel，extractittwicewith25mlportionsofchloroform.Combinethetwoportionsofchloroformina100mlroundbottomfl

14、ask，Assembleanapparatusforsimpledistillationandremovethechloroformbydistillation.Useasteambathtoheat.Theresidueinthedistillationflaskcontainsthecaffeineandispurifiedasdescribedbelow(crystallization).Savethechloroformthatwasdistilled.Youwillusesomeofitinthenextstep.Theremaindershouldbeplacedinacollec

15、tioncontainer.69Crystallization(Purification)Dissolvetheresidueobtainedfromthechloroformextractionoftheteasolutioninabout10m1ofthechloroformthatyousavedfromthedistillation.Itmaybenecessarytoheatthemixtureonasteambath.Transferthesolutiontoa50mlbeaker.Rinsetheflaskwithanadditional5m1ofchloroformandcom

16、binethisinthebeaker.Evaporatethenowlight-greensolutiontodrynessbyheatingitonasteambathinthehood.Theresidueobtainedonevaporationofthechloroformisnextcrystallizedbythemixedsolventmethod.Dissolveitinasmallquantity(about2to4ml)ofhotbenzeneandaddjustenoughhighboiling(60Cto90C)petroleumether(orligroin)tot

17、urnthesolutionfaintlycloudy.Alternatively，acetonemaybeusedforsimplecrystallizationwithoutasecondsolvent.CoolthesolutionandcollectthecrystallineproductbyvacuumfiltrationusingaHirschfunnel.Crystallizetheproductthesamewayasecondtimeifnecessary，andallowtheproducttodrybyallowingittostandinthesuctionfunne

18、lforawhile.Weightheproduct.Calculatetheweightypercentageyieldbasedonteaanddeterminethemeltingpoint.Ifdesired，theproductmaybefurtherpurifiedbysublimationasdescribedinthenextexperiment.TheDerivativeDissolve0.20gofCaffeineand0.15gofsalicylicacidin15mlofbenzeneinasmallbeakerbywarmingthemixtureonasteamba

19、th.Addabout5mlofhighboiling(60Cto90C)petroleumetherandallowthemixturetocoolandcrystallize.Itmaybenecessarytocoolthebeakerinanicewaterbathortoaddasmallamountofextrapetroleumethertoinducecrystallization.CollectthecrystallineproductbyvacuumfiltrationusingaHirschfunnel.Drytheproductbyallowingittostandin

20、theair，anddetermineitsmeltingpoint.Checkthevalueagainstthatintheliterature.Submitthesampletotheinstructorinalabeledvial.SelectedfromPaviaDonaldL.IntroductiontoOrgantcLaboratoryTechniques:aContemporaryApproach.W.B.SaundersCompany,1976.ExercisesAnswerthefollowingquestions:68Canyoulistseveralplantsthat

21、containcaffeine?Whatkindofmethodcanbeusedtoisolatecaffeinefromtea?Howdoesmanusecaffeineinthedailylife?Competingthefollowingparagraph.ChooseNotMoreThanThreeWordsfromthepassageforeachanswer.Theactiveingredientthatmakesteaandcoffeevaluabletomanis.Caffeineisan，aclassofnaturallyoccurringcompoundscontaini

22、ngnitrogenandhavingthepropertiesofanorganicaminebase.Teaandcoffeearenottheonlyplantsourcesofcaffeine.Othersinclude:kolanuts，mateleaves，guaranaseeds，andinsmaallamount，cocoabeans.Place35gofgroundcoffeeaboilingstoneand125mlofwaterintoa500mlroundbottomflaskequippedwithaforreflux.theunusedopeningsinthefl

23、askandheatthemixtureunderforabout20minutes.Useatoheat.Duringtheheatingperiod，assembleavacuumfiltrationapparatus.Whenboilingactionhasstoppedandthecoffeegroundshavesettledsomewhat，butwhilethesolutionisstillhot，filterthesolutionthroughabyvacuumfiltration.PutthefollowingintoChinese:celluloseglucosechlor

24、oformbeakercrystallizationpurificationapparatusfilterpaperhydroxylgroupcarboxylgroupbenzeneacetoneevaporationinsolublecondensationresidue第2部分生化制藥6單元的分離從茶葉中的咖啡因在這個實驗中，咖啡因會被孤立于茶葉。在的主要問題：隔離是，咖啡因不會出現(xiàn)在茶葉單，而是由其他的，它必須伴隨著分離的天然物質(zhì)。對茶葉的主要成分是纖維素，這是所有植物細胞的主要結(jié)構(gòu)材料。纖維素是葡萄糖的聚合物。由于纖維素幾乎不溶于水，它提出了在隔離程序沒有問題?？Х纫颍硪环矫?，易溶于

25、水，是提取到解決方案的主要物質(zhì)之一，被稱為“茶”?？Х纫虬ǜ哌_5通過在茶樹葉片材料的重量百分比。鞣質(zhì)也溶于熱水用于提取茶葉。單寧一詞不是指為一個單一的化合物，甚至有相似的化學(xué)物質(zhì)的結(jié)構(gòu)。它是指一種化合物具有某些共同屬性的類。單寧分子量之間有酚類化合物500和3000。它們被廣泛用于“曬黑”皮革。他們從水溶液中沉淀alkaloidsz和蛋白質(zhì)。單寧通常分為兩類：那些可以水解，哪些不能。第一種類型的單寧是茶中通常會產(chǎn)生葡萄糖和沒食子酸水解時，。這些單寧是沒食子酸和葡萄糖酯。它們代表，其中在一些葡萄糖的羥基被酯化digalloyl群體結(jié)構(gòu)。非水解性單寧是茶中的兒茶素縮合聚合物。這些聚合物的結(jié)構(gòu)不統(tǒng)

26、一，但兒茶素分子在環(huán)通常與位置4和8在一起。當單寧分為熱水提取，部分水解水解的是，這意味著自由沒食子酸也發(fā)現(xiàn)茶葉中。憑借他們的酚羥基，單寧酸，沒食子酸的羧基憑借其，都是酸性的。如果碳酸鈣，一個基地，被添加到茶水，這些酸的鈣鹽的形成?？Х纫蚩梢杂寐确绿崛〔枞~基本解決方案，但沒食子酸的鈣鹽和單寧酸不溶于氯仿，并保持在水溶液中落后。一個茶解褐色是由于黃酮類色素，葉綠素，以及他們各自的氧化產(chǎn)物。葉綠素雖然有點溶于氯仿，茶葉中的其它物質(zhì)大多數(shù)都不是。因此，基本解決氯仿萃取去除茶幾乎純咖啡因。氯仿很容易去除蒸餾(由61C)離開原油咖啡因。咖啡因可能是重結(jié)晶純化或升華。兒茶素沒食子酸在本次實驗的第二部分，咖

27、啡因會被轉(zhuǎn)換為衍生工具。衍生的一種化合物是第二個化合物，已知熔點，從一個簡單的化學(xué)反應(yīng)形成的原始化合物。在努力做一個積極的鑒定一種有機化合物，它往往是習(xí)慣性地轉(zhuǎn)換成一個派生它。如果第一個化合物，咖啡因在這種情況下，它的衍生物都有匹配熔點在化學(xué)文獻（例如，一本手冊），這是假設(shè)是沒有巧合，報道的第一個化合物，咖啡因身份已絕對成立?？Х纫蚴且环N基礎(chǔ)，并將與酸反應(yīng)，讓鹽。使用水楊酸，鹽衍生物的咖啡因，咖啡因水楊酸，將在以確定身份的咖啡因從茶葉孤立。特別說明時要小心處理氯仿。它是一種有毒溶劑，你不應(yīng)該過分或吸到它灑在自己身上。當丟棄花茶葉，不要放在水槽里，因為他們會阻塞排水管。他們擲入垃圾容器。程序放在

28、一個500毫升三頸圓底與一個裝有回流冷凝器的燒瓶干茶葉25克，25克碳酸鈣粉，水250毫升。塞燒瓶中加熱回流20分鐘左右的混合物未使用的開口。使用本生燈加熱。雖然解決辦法仍然是熱的，它靠重力過濾槽過濾器通過使用快速濾紙，女fE&D第617和S&S的第595號。您可能需要更改濾紙如果木屐。冷卻過濾（過濾液體）到室溫，用分液漏斗中，用25毫升氯仿提取部分兩次。結(jié)合氯仿中的兩個100毫升的圓底燒瓶部分，組建一個簡單的蒸餾設(shè)備和蒸餾除去氯仿。使用熱蒸汽浴室。蒸餾燒瓶中的殘留物含有咖啡因和被提純?nèi)缦拢ńY(jié)晶）中所述。這是保存蒸餾氯仿。您將在下一步中使用了一些。其余應(yīng)放置在一個集合容器。69結(jié)晶（凈化）解散的茶溶液對氯仿，您從氯仿萃取蒸餾保存10m1取得的殘留物。它可能需要加熱的混合物上的蒸氣浴。轉(zhuǎn)移到一個50毫升的燒杯的解