isomers是什麼意思mers在線翻譯讀音例句

化学原料药开发-异构体的分类ISOMERS

Definition

Isomersarecompoundsthathavethesamemolecular(empirical)formula,but

differentstructures,anddemonstratephysico-chemicalandpharmacologicaldiffere

nces

Classification

StructuralIsomers

Definition

Compoundswiththesameempiricalformula,butwhoseatomsareconnected

inadifferentsequence

Chainisomers

havedifferentbranchingpatternsofcarbonchains

Positionisomers

thefunctionalgroupislocatedondifferentcarbonsinthechain

tendtohavesimilarchemicalproperties

Functionalgroupisomers

havedifferenttypesofbondsandhencedifferentfunctionalgroups

tendtohaveverydifferentchemicalpr古诗300首小学生 operties

Tautomers

compoundsinwhich,underdifferingconditionsegpH,thesubstituentgroupi

ngsmayaltertheirposition

structuralisomersthatreadilyconvertfromoneisomericformtoanotherand

henceexistinequilibrium

Stereoisomers

Definition

Compoundswhichhavethesameempiricalformulaandwhoseatomsareatta

chedinthesamesequence,butdifferinthespatialarrangementoftheatoms

Significance

mayhavemarkedpharmacokineticandpharmacodynamicdifferenceseglevo-

bupivacaineislesscardiotoxicthandextro-bupivacaine,onlylevoisomerofmorph

inehasopioidactivity

different3dimensionalarrangement→differentabilitytointeractwithrecept

ors,enzymesandnon-specificbindingsites

isomer-specificabilityofadrugtoproduceapharmacologicaleffectiseviden

cesupportingthepresenceofreceptors

Enantiomers

stereoisomersthatarenon-superimposablemirrorimages(likeleftandrighth

ands)

containachiralcentre(anasymmetriccarbonwithfourdifferentgroupsattach

edtoit)

identicalphysicalproperties,exceptthedirectioninwhichtheyrotatepolarise

dlight

ClassificationSystems

a)Rotationofpolarisedlighttothe:

left:levorotatoryl-(-)

right:dextrototatoryd-(+)

aracemicmixtureconta课组词 insequalamountsoflevoanddextroisomersandther

eforehasnooverallrotatingeffectonpolarisedlight

b)CahnIngoldPrelogconvention

Ligandsaroundthechiralcarbonareassignedaprioritybasedontheiratomic

number

(higheratomicnumber=higherpriority)

Rectus(R-)prioritiesincreaseinclockwisedirection

Sinister(S-)prioritiesincreaseinanti-clockwisedirection

atthissystemhasnothi

ngtodowith

rotationofpolarisedlightandthereforeclassificationinonesystemdoesnota

lways

correspondtothesameclassificationintheother.“Coincidentally”,thissee

minglyarbitrarynomenclature(R,S).

c)SimplesugarsandaminoacidscanbeclassifiedasD-orL-accordingtoth

eclockwiseoranticlockwisespatialarrangementofCOOH,NH3,Handhydrocar

anoldclassificationsystem,don’tbot

herlear多难兴邦 ningit,justbeawareofit.

(D-andL-arenottobeconfusedwithd-andl-!!)

Diastereoisomers

Stereoisomerswithdifferentorientationofsubstituentgroupsoneithersideof

arigidbond(egdoublebondorringstructure)

Alternatively,canbethoughtofasisomerswithtwochiralcarbons

Classificationsystems

a)cis-andtrans-

cis-functionalgroupsareonthesamesideofthedoublebond

trans-functionalgroupsareonoppositesidesofthedoublebond

egmivacuriumispresentedasamixtureofisomers:

trans-trans60%

cis-trans30%

cis-cis10%

b)othersystemsincludesyn-/anti-andZ-/E-(forgetaboutthiscrap)

ClassificationofIsomers

Isomers:Compoundsthathav毛遂自荐造句 eidenticalchemicalandmolecularformulasbut

differinthenatureofsequenceofbondingoftheiratomsorintheirarrangementof

ingtotheirtopologytheyareclassifiedaseitherstructuralo

sarebroadlyclassifiedintotwobroadcategories:

1.1

StructuralIsomers:Compoundsthathavethesameatomspresentbutdifferin

v

edistinguishedbypla

nardiagramssuchasfischerprojections.

1.1.1

SkeletalIsomers:Compoundsthathavethesamefunctionalgroups,butdiffer

mple:

pentane,2-methylbutaneand2,2dimethylpropane.

1.1.2

PositionalIsomers:Compoundsthathavethesamefunctionalgroups,butare

mple:butan-1-olandbutan-2-ol.

1.1.3

FunctionalIsomers:

mple:ethanolandmethoxymethane.

1.1.4

Tautomers:Compoundswhosestructuresdifferinarrangementofatomsbutw

hichareindynamicequilibriumwitheachother.

1.1.4.1

Keto-Enoltautomerism:

1.1.4.2

Ring-Chainisomerism:seenincaseofglucose

1.2

Stereoisomer:Compoundsthathavethesamechemicalformula,sameatoms,

sameconnectivityanddifferonlyinthearrangementoftheiratomsinspace.

1.2.1

Anomers:Stereoisomerswherethemoleculeiscyclizedandthedifferencein

ofaldosestheanomericca

einopenchainfor

misnotchiralatC1butinringformhastwoopticallyactivestereoisomers:alpha

&betaglucose.

1.2.2

RotamersandConformers:Onthebasisofspatialarrangementofatomsinthe

moleculethatcanbeachievedbyrotation(ortorsion)aroundoneormoresinglebo

nds,mersassumethechair/b

oatandequitorial/rsassumethedifferentnewmannprojections

(staggered/eclipsed/gauche).

1.2.3

ConfigurationalIsomershaveachiral(stereogeniccenter).Chiralcenterrefers

eculeissaidtopossess

chiralityandtohaveastereogenic

center.

1.2.3.1

Enantiomer:Stereoisomersthatarenon-identical,mirror-symmetricforallato

ms,nonsuperimposable,opticallyactive(/dextro-rotatory),invertedonlyb

ucose.

1.2.3.2

Diastereomer:Stereoisomersthatarenotmirrorimages,buthaveidenticalcon

figu林暗草惊风拼音 rationforatleastoneasymmetriccenterandatleastonedifferentconfiguration

inehas2chiralcentersandthere

fore4diastereomers.

1.2.3.2.1

Epimers:Theyareaspecialcaseofdiastereoisomerismwherethereisadiffer

ucoseandD-galactoseareepimers.

1.2.3.3

Meso-isomer(Achiralmolecules):super-imposablemirrorimageswhichhave

-isomershavetwoplanesofsymmetry;the

usualmirrorplaneofreflectionandasecondplaneperpendiculartoitthroughthe

molecule(inthe``middle\'\'ofthemolecule).Theasymmetriccentersaredistribute

pt

icalrotationsfromthetwo``halves\'\'ofthemoleculecancelout.

1.2.3.4

GeometricIsomers:

thebondisC=C,thetermsarecis/trans;ifthebondisC=N,thetermsaresyn(cis-l

ike)andanti(trans-like).Forexample:cis-2-buteneandtrans-2-butene.

ChiralCenterNamin为汉语拼音 gClassification:

•+/-Indicatesthedirectioninwhichplaneofpolarizedlightisrotated(clock

wise/anticlockwise).

•D/L(Dextrorotatory/Levorotatory):Planeofpolarizedlightisrotatedtothe

rightorleft.

•alpha/edforsugars.

•R-Sconvention:Thefourgroupssur描写十五月亮的诗句 ro描写古代儿童生活的古诗 undingthestereocenteraregivenap

riorityfroma->d(fromhighesttolowest).Themoleculeisthenobservedfromthe

emainingthreegroupsformaclockwise

array(a->b->c),inanti-clockwisethenSconventio

tyisassignedaccordingtoatomicnumber,withthehighertheatomicnum

usedforchiralmolecules(enantiomers/diastereo

mers/epimers).

•E-Zconvention:Thetwogroupsattachedtothecarbonaroundthedoubleb

wohighestprioritygroupsareonthesamesideof

thedoublebond,thenthemoleculeisgiventheZconvention(similartocis);andif

ontheoppositesidethenEconv被疯批们日夜浇罐po七酱 ention(similartotrans).e.g.:1-chloro-1-bromo-2-i

tyisassignedaccordin

gtotheatomicnumber;withthehighertheatomicnumber,thehigherthepriority.

earetwoidenticalatomsattachedt

othestereocenter(saythecarbonofthemethylgroupandcarbonoftheethylgrou

p)thenworkalongthechainoftheattachedgroupuntiladifferenceoccurs.