绿色化学：第二章 绿色化学

第二章绿色化学Chapter2GreenChemistry

2.1

什么是绿色化学

TheconceptofGreenChemistry

2.2

大力发展绿色化学

PromotingthedevelopmentofGreenChemistry

2.3

化学反应的原子经济性

AtomEconomyofchemistryreaction

2.4

原子经济性和环境效益

AtomEconomyandenvironmentaleffects

2.5

绿色化学的任务

Researchareaofgreenchemistry

2.6

绿色化学的十二条原则

TwelveprinciplesofgreenchemistryGreenChemistryisinvestigatedworld-widely

绿色化学是化学研究的前沿。

Greenchemistryisanactiveintercrossing(交叉)researchareaintheworld,itdealswiththefrontierofchemicalresearch.绿色化学的目标Nopollutionshouldbeaccompaniedinchemicalprocesses,thisistosay,eliminatethepotential(潜力)ofpollutionbeforeitoccurs.Therealizationofthisgoalmeansnoenvironmentalcontrolisneeded,becausetherewillbenopollution.绿色化学的内涵GreenChemistryistheapplicationofchemicalprinciples,chemicaltechnologiesandchemicalmethodstoallchemicalsandchemicalprocessestoreduceoreliminatetheuseofhazardousstartingmaterials,hazardousprocesses,hazardoustargetproducts,hazardousauxiliarysubstances(suchassolvents,separationagents)intheproductionanduseofchemicals.By-products

areexpectedtobeavoidedasthoroughlyaspossible,andthestartingmaterialsbeutilizedascompletelyaspossible,thussatisfyingasustainablecivilization.Itisthechemistrywhichcouldreduceandeliminatepollutionfromtheverybeginningandcurepollutioneternally.GreenchemistrywayBringaboutatemporarysolutionTreattheexistedwasteTreatwasteProvideapermanentcureEliminatewastefromtheoriginNowasteproducedNotneedforwastetreatmentTraditionalwayWasteproducedthentreatFacingtheincreasingenvironmentalpollution

绿色化学是可实现

GreenChemistryisrealizableThegoalofgreenchemistryistoseekforperfection(byovercomingdifficulties).Oppositeopinions:

itisdifficulttoquantify

thetoxicity(毒性)andharmfulness(危害)ofasubstancetohumanbeingsandtoenvironment.Examplesalreadyrealizedgiveevidencesstronglytoillustratethatgreenchemistryisrealizable.Relationshipbetweenstructureandproperties——givesuscluetopredicttheharmfulnessofsubstances.Wecouldcompareandselectthemostfavorablesubstanceandmethodunderspecifiedconditions.进一步认识绿色化学

DeeperviewpointsonGreenChemistry

Scientificviewpoints:GreenChemistryconcernsnewresearchareaofchemistry.Itrejuvenates(更新)thecontentsofchemistry.Economicalviewpoint:GreenChemistryprovidesfundamentalprinciplesandtechniquestoutilizeeffectivelythestartingmaterials(resources)andenergy,meanwhilethecostoftheproductionisreduced,thussatisfyingtherequirementsofsustainabledevelopment.

environmentalviewpoint:GreenChemistryprovidesnewprinciplesandtechniquestocutdownpollutionoriginally(从源头上)andeternally.

2.1

TheconceptofGreenChemistry

2.2

PromotingthedevelopmentofGreenChemistry

2.3

AtomEconomyofchemistryreaction

2.4AtomEconomyandenvironmentaleffects

2.5Researchareaofgreenchemistry

2.6Twelveprinciplesofgreenchemistry

SatisfyingthedemandforsustainabledevelopmentofhumansocietySatisfyingtherequirementofscienceandeconomy

Environment&resourceSimultaneouslygiveoutGreenChemistrySolutionRecyclableeconomySustainabledevelopmentCrisesRequirementGreenChemistrySatisfyingtherequirementforthedevelopmentofscienceandeconomy

Chemistryitselfdevelopsinaccordancewiththechangeofresourcesandofthesocialrequirement.Itshouldalsoberenewedinmethodologyandcontent.Greenchemistryappears.ScientificallyChemicalindustryplaysanimportantroleintheindustrialensemble

Britain,Germany,USAChemicalenterprisesmakegreateffectstoreducetheircost,andincreasetheircostbytreatingthepollutantstheyproduced.Greenchemistryprovidesnewwayswhichcouldsatisfyboththedemandsofchemicalproduction.Economically

2.1

TheconceptofGreenChemistry

2.2PromotingthedevelopmentofGreenChemistry

2.3AtomEconomyofchemistryreaction

2.4AtomEconomyandenvironmentaleffects

2.5Researchareaofgreenchemistry

2.6Twelveprinciplesofgreenchemistry

Atomutilization原子利用率Atomeconomyofchemicalreaction化学反应的原子经济性Increasetheconversionofthereactants,theselectivityoftheproducts提高反应物的转化率和产物的选择性2.3AtomEconomyofchemistryreaction原子利用率

Atomutilization

Theconceptwasusedto

quantify

thewaste(by-products)formedwhenacertainamountoftargetproductwasmanufacturedinachemicalreaction.RogerA.Sheldon1992Atomutilization==Theamountoftargetproductformed╳

100%TheamountofallproductsformedstoichiometricallyTheamountofreactantsusedTheamountoftargetproductformed╳

100%

Thetwomaincharacteristicsofchemicalreactionwith100%atomutilization:Thereactantscouldbefullyutilized,andtheresourcecouldbemostpossiblyusedeconomicallyThewastecouldbeminimizedExample1

：Thepreparationofepoxy-ethane(环氧乙烷)fromethylene

TraditionalwayDisadvantagesofthetraditionalmethod1.Theatomutilizationcouldreachonly25%,i.e.,1kgoftargetproduct/3kgofwastes.2.ThereactantCl2isharmful,iterodes(腐蚀)theequipmentandinjures(伤害)humanbeings,thusdemandingspecialequipmentandspecialprotectionmeasure.3.Separationandpurification(纯化)processesarenecessarytoobtainusefulproduct.Ifeverystepcouldobtain100%selectivityand100%yield,thenNewgreenerwaySilvercatalystisusedtoconvertethylenedirectlytothetargetmoleculebyusingoxygenastheoxidant,whichgives100%atomutilization.

Highatomeconomy(100%)

Oxygenissafetohumanbeingsandtoenvironment.

Noseparationorpurificationisneeded.AdvantagesofthenewgreenermethodIftheselectivityofthereactioncouldreach100%

Example2：Thepreparationofepoxy-propane(环氧丙烷)

Traditionalway1.Theatomutilizationcouldreachonly31%,i.e.,1kgoftargetproduct/2kgofwastes.2.ThereactantCl2isharmful,iterodestheequipmentandinjureshumanbeings,thusdemandingspecialequipmentandspecialprotectionmeasure.3.Separationandpurificationprocessesarenecessarytoobtainusefulproduct.Ifeverystepcouldobtain100%selectivityand100%yield,thenDisadvantagesofthetraditionalmethodNewgreenerwayDirectoxidationcatalyzedbytitania-silica

Theatomutilizationishigh(76%)Theby-product----waterisenvironmentallybenign.

Hydrogenperoxideissaferthanchlorinetohumanbeingsandtoenvironment.Iftheselectivityofthereactioncouldreach100%Advantagesofthenewgreenermethod

Thisprocessusestheby-productsfromphenol(苯酚)industryandacrylonitrile(丙烯腈):acetoneandhydrocyanicacid.H3CCOCH3

HCNExample3：Thesynthesisofmethylacrylate(丙烯酸甲酯)

TraditionalwayTheoverallreaction1.Theatomutilizationcouldreachonly46%,i.e.,1kgoftargetproduct/1kgofwastes.2.ThereactantHCN

isharmful,iterodestheequipmentandinjureshumanbeings,thusdemandingspecialequipmentandspecialprotectionmeasure.3.Separationandpurificationprocessesarenecessarytoobtainusefulproduct.Ifeverystepcouldobtain100%selectivityand100%yield,thenDisadvantagesofthetraditionalmethodThisprocessutilizestheby-productpropyneCH3C≡CHfromthedissociation(e.g.Pyrolysis(热解))ofnaphtha(石脑油),andcarbonmonoxide.Newgreenerway

Theatomutilizationishigh(100%)

Carbonmonoxideandmethanolaresaferthanhydrocyanicacidtohumanbeingsandtoenvironment.Nowaste

producedIftheselectivityofthereactioncouldreach100%Advantagesofthenewgreenermethod

2.1

TheconceptofGreenChemistry

2.2

PromotingthedevelopmentofGreenChemistry

2.3

AtomEconomyofchemistryreaction

2.4AtomEconomyandenvironmentaleffects

2.5Researchareaofgreenchemistry

2.6Twelveprinciplesofgreenchemistry

Definition：

TheratioofatomsappearedinthetargetmoleculestoalltheatomsofthereactantsThereactionwith100%atomutilizationisidealatomeconomicalreaction.

1991，BarryM.Trost1996,ThePresidentialGreenChemistryChallengeAwardofUSAHowtodesign

atomeconomicalreactions

如何设计原子经济反应?DeficiencyofthetraditionalsyntheticwaysA+BC＋DwasteTargetmoleculeForatargetmoleculeC

Ifthetraditionalwayis

A+BC+DThisprocessinevitablyproducestheby-productD,whichshouldbetreatedandcouldbeconsideredaswaste.Becausethisisthechemicalreaction,ifwewanttousethisreaction,wecouldnotavoidthisdilemma.AtomiceconomicreactionsE+FCTargetproductThusweshoulddesignnewatomeconomicalreactionsas

E+FCAdvantages:alltheatomsinthereactantsE

andFenteredinthetargetmoleculeC,makingtheatomutilizationbe100%.Noby-productformedThus,nowastefortreatmentNopollutionProblemThetypesoforganicreactions:PleaseanswerWhichkindsareatomicallyeconomical?ExampleThesynthesisofhaloalkane

卤代烷烃Atomeconomy:100%Noby-productNopollutionTheconsumptionofresourceisminimized。3molestargetmolecules/1moleby-product,Wasteresourcesandtheby-productisakindofpollutant3ROH+PX3

3RX+H3PO3RX’+NaX

RX+NaX’R’CH=CH2+HX

RX1moletargetmolecules/1moleby-product，Wasteresourcesandtheby-productisakindofpollutant尽量提高反应物的转化率（conversion)和

目标产物的选择性(selectivity)

Atomeconomyisnecessaryforareactiontonotproducewaste,butitisnotenough.LowequilibriumconversionParallelreactions

2.1

TheconceptofGreenChemistry

2.2

PromotingthedevelopmentofGreenChemistry

2.3

AtomEconomyofchemistryreaction

2.4

AtomEconomyandenvironmentaleffects

2.5Researchareaofgreenchemistry

2.6Twelveprinciplesofgreenchemistry

Environmentalfactor(环境因子)

Itisusedtoquantifytheeffectsofproductionprocesstotheenvironment

Idea:AllothercompoundsformedotherthanthetargetproductareconsideredtobeWASTE.RogerA.Sheldonin1992EnvironmentalfactorE=TheamountofwasteTheamountoftargetproductThelargerEThemorewasteformedThemoreseriousthepollutionIftheatomUtilization=100%E=0Theenvironmentalfactorofseveralindustries

Industries

Production/t

EPetrol106~108

~0.1FundamentalChemicals104~1061~5Finechemicals102~1045~50Pharmacy10~103

25~100Buttheenvironmentalpollutionisstronglyassociatedwiththeharmfulperformanceofthewaste.Environmentalquotient(EQ)(环境商)TheEfactorjustgivestheratioofthewasteandthetargetproduct.EnvironmentalquotientE-----EnvironmentalfactorQ-----Theextentofhazardousness（危害程度）ofthewastetotheenvironmentobtainedfromtheperformanceofthewasteintheenvironment.EQ＝E×Q

2.1

TheconceptofGreenChemistry

2.2

PromotingthedevelopmentofGreenChemistry

2.3

AtomEconomyofchemistryreaction

2.4

AtomEconomyandenvironmentaleffects

2.5

Researchareaofgreenchemistry

2.6Twelveprinciplesofgreenchemistry

Designingsaferandeffectivetargetmolecules

SeekingforsaferstartingmaterialsSeekingforsafersyntheticprocessesSeekingfornewsaferconversionwaysSeekingforsafernewreactionconditionsGreener,SaferThedesigningofsaferchemicalsistheuseoftherelationshipbetweenmolecularstructureandproperties(structure-activityrelationship,SAR构效关系)andmolecularmanipulation(分子控制)methodtoobtainmoleculeswithmaximizeddesiredfunctionsandminimizedharmfulness.（功能最大化，毒性最小化）In1983,aseminaronthedesigningofsaferchemicalshasbeenholdinWashington.

Designingsaferandeffectivetargetmolecules

（设计安全有效的目标分子）Itinvolvestwoaspects:Thedesigningofnewsafeandeffectivemolecules.2.

Thedesigningofnewsaferandeffectivemoleculestoreplacethemolecules

which

existed

effectivebutnotbenign

Wehavemorethan18,000thousandsofcompoundsuptonow,while

600thousands

ofnewcompoundsappeareveryyear.DesigningsaferandeffectivetargetmoleculesTraditionalwaysoffindinganeffectivemolecule:PracticalneedssynthesistestsynthesistestNewmoleculardesigningways:TrialanderrorsPracticalneedsdesigningbySARsynthesisGuidedtheoreticallytestWorkingdesk+computer+ventilationcupboardDesigningsaferandeffectivetargetmoleculesExampleSeekingforNewstartingmaterials

（寻找安全有效的反应原料）

Seekingnewstartingmaterialstosubstitutetheactuallyusedhazardousandpoisonousmaterials

Example1UsingCO2tosubstitutephosgene

（光气）inthesynthesisofpolyurethane(聚氨酯)

Example2Eliminationtheuseofhydrocyanicacid（氢氰酸)

Example3Thesynthesisofadipicacid（己二酸）usingnewsafestartingmaterialsEliminatingthepoisonousphosgene

（光气）inthesynthesisofpolyurethaneandpolycarbonateExample1Polycarbonate(聚碳酸酯)Phosgeneiswidelyusedfortheproductionof:isocyanate(异氰酸酯)polyurethane(聚氨酯)Isocyanateisfirstsynthesizedbythereactionofphosgeneandamine,andthenusingisocyanatetoproducepolyurethane.TraditionalwayRNH2+COCl2RNCO+2HClRNHCO2R1Thesynthesisofisocyanate(异氰酸酯)Whatkindsof

functionalgroup

wouldphosgeneprovideinachemicalreaction?

Whichkindofcompoundcouldbeemployedtosubstitutephosgene?providing

-CO

groupCarbondioxideisusedtosubstitutephosgeneintheproductionofisocyanate(providingcarbonylgroup)Thefunctionofphosgene:providing-COgroupRNH2+CO2RNCO+H2ORNHCO2R1NewgreenerwayTheeliminationoftheuseofHCN(hydrocyanicacid)

bychangingtheprocessExample2Thesynthesisofsodiumiminodi-acetate(亚氨基二乙酸二钠)Traditionalwayinvolvestwosteps:按照化学NH3+2CH2O+2HCN—①NCCH2NHCH2CN—②+2NaOH→NaO2CCH2NHCH2CO2Na+NH3Anewstartingmaterial

HOCH2CH2NHCH2CH2OH

(diethanolamine,二乙醇胺)isused

NewgreenerwayExample3Thesynthesisofadipicacid（己二酸）bychangingstartingmaterialTraditionalwayCouldanyonetellmethe

disadvantagesofthismethod

PhotochemicalsmogDepletionofozone,AcidrainDisadvantagesofthetraditionalmethodThestartingmaterial(Benzene)

ishazardous(致癌物)ThereleaseofnitrogenoxideswhicharemultifunctionalpollutantsUseofheavymetals(cobalt)Eliminationoftheuseofsolvent（溶剂）,theuseofhazardousbenzene,thecorrosivecapacityofhydrogenperoxide（双氧水）

isnotassevereasnitricacid,nopollutantsproduced.KamzuhikoSato,1998,Science,281:1646-1647Newgreenermethod1Thesynthesismethodiswidened.DrathandFrost,

1990,1991Newgreenermethod2Notonlyeliminatetheuseofbenzene,butalsodevelopanewmethodtouserenewablebiomass(glucose).

Usingofrenewablestartingmaterial

利用可再生资源

150yearsago,industrialorganicchemicalswereallderivedfrombiomass（生物质）

originatedfromplants

Theuseofbiomassasstartingmaterialforenergyandchemicalsproductionregainmuchattention,becauseofitsrenewability.CoalOilNaturalgas

StartingmaterialsBiomassIndustrialrevolutionOnekindofsolarenergyBiomassItmustdegeneratebeforeitcouldbeeffectivelyused.Biomass：Starch(淀粉)Lignin(木质素)Theburningofstraw:wasteofresourcewhilepollutingTechnicalchallenges

CollectionofbiomassVariationofcompositionsofdifferentkindsofbiomassandgrownfromdifferentareaoftheworldContinuousoperationHandlingofmixturesratherthanpurecompoundUpgrading（提取）andSeparation（分离）oftheproductsHowtouseeffectivelythebio-productsFast-growingbambooFast-growingshrubsConvertbiomasstousefulproductsgreenchemically

将生物质转化为化学化工原料开发新资源实现资源持续利用AgriculturalwasteSeekinganddesigning

saferandeffectivesyntheticroutes

寻找和设计安全有效的合成路线Idealsyntheticroute

理想的合成路线PaulAWender1996thestartingmaterialusedshouldbethecheapestandmostfeasible;theoperationandmanipulationshouldbesimple,safeandenvironmentallybenign;thereactionrateshouldbefastandtheyield

ofthetargetproductsshouldbeashighaspossible.ExampleThesynthesisofpara-phenylenediamine(对苯二胺）fromnitrobenzene（硝基苯）LetusanalyzefourpossibleroutesinagreenchemistryviewpointRoute1Theamountsofreactants:1062Targetmolecule:

108Waste:

954Atomutilization:Theoverallreaction

10%Route2Theoverallreaction

Theamountsofreactants:

300Targetmolecule:

108Waste:

192Atomutilization:36%按照化学Route3Theoverallreaction

Theamountsofreactants:

543Targetmolecule:

108Waste:

435Atomutilization:20%Route4Theoverallreaction

Theamountsofreactants:162Targetmolecule:

108Waste:

54Atomutilization:67%Aggregativeanalysis

Fromtheviewpointofatomeconomy,route4isthemostfavorablecomparingtoothers。Inroutes1&2,becauseoftheprotectionof-NH2innitration,onemoleofaceticanhydrideisneededand2molesofaceticacidareformedaswaste,whileinroutes3&4,theprotectionstepwasnotneeded.

Practicalneed:

greatamountofpossibleroutesforagivingtargetmolecule.

Computeraided

designingofsyntheticroute

计算机辅助设计合成路线CoreyandBersohn,30yearsagouse

computertohelpdesigningofsyntheticroute30⇒30×30

⇒30×30×30

⇒

……

⇒305>24millionroutesItisnecessary!e.g.Ifthesynthesisofacompoundneeds5steps,and30methodsarepossibleforeachstep,thuswewillhaveTheprogressofcomputationtechnologyItispossibleTheprogressincomputerscienceandtechnologyConstructionofadatabaseofchemicalreactionsascompleteaspossible.PutforwardourrequirementLetthecomputergiveusthepossiblestartingmaterialswhichcouldformthetargetmoleculeTechnicalWayFurthersearchforthestartingmaterialusingtheformerstartingmaterialasthetargetmolecules…………

untiltheprovidedstartingmaterialisneededCompareallpossibleroutes,andchoosethemostfavorableonefromtheviewpointofeconomicalandenvironmentaleffect.TechnicalWaySeekingfor

newconversionmethods（寻找新的转化方法）Catalyticplasma（催化等离子体）moreElectrochemicalconversion（电化学转化）morePhotoandotherradiationconversion（光和其它辐射方法）moreSeekingfor

unconventionalconversionways

Thesynthesisofgasolinefromcarbondioxideandnaturalgas(methane,甲烷)

CO2+CH42CO+2H2Gasoline→→NickelcatalystFTprocessChangjiunLiu,TianjingUniversityTraditionalthinkingupCO2+CH4GasolineCatalyst&plasmaconditionPlasma:breakingofthereactantmoleculesCatalyst:formingoftheproductmoleculesCatalyticplasmaUsingelectrochemicalwaysElectricitycanbeusednotonlyasanenergysupplyforchemicalreactions,itcouldalsoaffectchemicalreactionindifferentaspectsandprovidenewwaysforittooccur.Thefollowingexamplewillgiveussomedirectinformation.Usingelectrochemicalwaystoeliminatetheuseofhazardousstartingmaterialsandmakethereactiontooccuratmoderate

conditionsCyclizationreactionThecycleopenreactionofdioxane(二恶烷)、O-orS-heterocyclohexane(氧硫杂环已烷)useheavymetalcatalysttraditionally,andadditionalreactantsareneeded.EplingetcuselightasthereactingagenttorealizethesereactionandavoidthepollutioncausedbyheavymetalsPhotoandotherradiationconversion

Seekingfor

Safeandeffective

reactionconditions

寻找安全有效的反应条件

Seekingforsafeandeffectivecatalyst

寻找安全有效的催化剂LoadingofactivecomponentonsuitablesupportReplacingliquidacidsbysolidacidsSeekingforsafeandeffectivereactionmedium

寻找安全有效的反应介质Usingsupercriticalfluid（超临界流体）asreactionmediumUsingwaterasreactionmediumLoadingofactivecomponentsonsuitablesupport

活性组分的负载化TraditionalFriedel-Craftsreactions：

hydrofluoricacid(氢氟酸),sulfuricacid(硫酸),aluminiumchloride(三氯化铝),boronfluoride(三氟化硼,borontrifluoride)areusedasthecatalysts.Thedisadvantages:Theoperationmustbedoneanhydrously(waterfree),3molesof

hydrogenchloridewillbereleasedwhenaccountingwater.Thesystemis

corrosive,strictoperationconditionsmustbecontrolled.

Lowselectivity

becauseoftheformationofpoly-alkyl-substitutedproductsandotherisomers.

ThesupportedcatalystK10-AlCl3，preparedbysupportingAlCl3onmontmorilonite(蒙脱土,imvite)showsactivityashighastheconventionalonesandhigherselectivityfortheformationofmono-alkylated（单烷基化）productthantheoldones.Usingsolidacidstoreplaceliquidacids

用固体酸代替液体酸

Acidicclay(酸性白土),mixedchlorides（混合氯化物）,molecularsieve(分子筛)etc.couldbeusedtoreplaceliquidacids.（1）：Someinevitablebarriersthatcouldnotbeovercomeinhomogeneouscatalysiscouldbeloweredinacertaindegreeortotallyovercom（2）：Thetemperaturerangecouldbewidenedto700-800K,andthuswideningtherangeofacidcatalysis.Example1:ThetraditionalFridel-Craftsacylationreaction:Targetproduct/Aluminiumchlorode（三氯化铝）,1/3Usingsupercriticalfluid(scf.)asreactionmediumWhatissupercriticalfluid?SupercriticalRegionPressureCriticalPointTemperaturePcTcLiquidVapourSolid超临界区Usingsupercriticalfluid(scf.)asreactionmediumThecharacteristicsofscf:Cheap,safeandpropertyadjustable.Scfsshowdifferentpropertyunderdifferentconditions,wecanadjustthesupercriticalconditionstoadjustitspropertyuntilitsatisfyourneedsforthereactiontooccur.Bi-phasecatalysisusingwaterasreactionmediumWater-solublecomplexcompoundscouldbeusedascatalyst,andthenthereactiontakesplaceattheinterfaceformedbetweenthewaterphaseandtheorganicphaseofthereactants.

Bi-phasecatalysisusingwaterasreactionmedium

（水作溶剂的两相催化法）Micelle（胶束）couldbeprovidedbyvaryingthecentralatomandtheligandaswellastheuseofsurfacants,thustheinterfacecouldbeenlargedandtheregionalconcentrationofthereactantscouldbeincreased.Byvaryingthestructureofthemicelle,thestero-structureoftheproductcouldalsobecontrolled.Thus,mildreactionconditions,highactivityandselectivitycouldbeaffordedforandtheseparationoforganicphaseandwaterphasebecomeseasy.Meanwhile,environmentalpollutioncouldbeavoided.Bi-phasecatalysisusingwaterasreactionmediumTraditionalway：Co-basedcatalyst,highpressureisneededRh-orPd-basedwater-solublecatalystBi-phasecatalysis

2.1

TheconceptofGreenChemistry

2.2

PromotingthedevelopmentofGreenChemistry

2.3

AtomEconomyofchemistryreaction

2.4

AtomEconomyandenvironmentaleffects

2.5

Researchareaofgreenchemistry

2.6

Twelveprinciplesofgreenchemistry

1:预防污染原则

ItisbettertopreventwastethantotreatorcleanupwasteafteritisformedNormalcost：

startingmaterialandreagent(intrinsic

thetreatmentanddisposalofchemicalsLargechemicalcompaniesinU.S.:expendituresonresearchanddevelopment

≈expendituresonenvironmentalhealthandsafetyInmanycasesthe“damage”ismerelythatsubstanceshavebeenuselesslyprocessedortransformed,costingenergy,money,timeforseparationfromproduct,andalmostalwaysrequiringtechnologytogetridofthemortorendertheminnocuous.Onetypeofwasteproductionthatisbothcommonandoftenthemostavoidableisstartingmaterialorreagentthatisunconverted.Whenonewastesstartingmaterial,oneispayingforthesubstancetwice.Thus,ifpossible,itisbettertocutpollutionfromitsoriginratheritisformed.2:原子经济性原则

Syntheticmethodsshouldbedesignedtomaximizetheincorporationofallmaterialsusedintheprocessintothefinalproduct

Theclassicevaluationoftheeffectivenessandefficiencyofasynthesisis“Yield”.This“Yield”totallyignorestheuseorgenerationofanyundesirableproductsthatareanintrinsicpartofthesynthesis.Itisbettertouseatomeconomytoevaluatesynthesisways.AtomicallyeconomyreactionsRearrangements(重排反应）Bydefinition,arearrangementreactionisareorganizationoftheatomsthatmakeupthe“old”molecule.Thusallatomsinthereactantsareincorporatedintotheproduct.Additionreactions（加成反应）Becauseadditionreactionsaddtheelementsofthereactanttoasubstratewithtotalinclusion(e.g.cycloadditions,brominationofolefins),theyareatomiceconomical.NonatomiceconomicalreactionsSubstitution（取代反应）Becauseinthiskindofreaction,onegroup(thesubstitutinggroup)displacesaleavinggroup,theleavinggroupisnecessaryawasteproductofthereactionthatisnotincludedinthefinalproduct.Elimination(消去反应）

Eliminationreactionstransformthesubstratebyreducingtheatomstogeneratethefinalproduct.Theeliminatedatomsarelostaswaste.3:无害化学合成

Whereverpracticable,syntheticmethodologiesshouldbedesignedtouseandgeneratesubstancesthatpossesslittleornotoxicitytohumanhealthandtheenvironmentThereareonlytwowaystominimizeriskofharmofanykind:MinimizetheexposureAvarietyofformscouldbetaken:protectiveclothing,engineeringcontrol,respiratorsetcMinimizethehazardTheintr