1-Organic Structure Determination

8/17/2019 1-Organic Structure Determination

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PENENTUAN STRUKTUR SENYAWAORGANIK Bagaimana kita mengetahui:

Bagaimana atom-atom berhubungan satu sama lain

I!atan mana "ang tunggal# rang!a$ %ua# atau rang!a$ tiga

Gugus &ungsi a$a "ang a%a %i %alam mole!ul tersebut

A$a!ah memili!i stereoisomer s$esi'!

Bi%ang $enentuan stru!tur sen"a(a organi!berusaha men)a(ab $ertan"aan %i atas*


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+ETO,E INSTRU+EN PENENTUANSTRUKTUR1. Resonansi Magnet Inti, Nu lear +agneti Resonan e .N+R/ 0 E!sit

inti atom melalui $en"inaran1$ema$aran &re!uensi ra%io* +emberi!anin&ormasi e!stensi& tentang stru!tur mole!ul %an hubungan atom-atom*

2. Infrared Spectroscopy (IR) 0 +emi u 2ibrasi mole!ul melalui$en"inaran1$ema$aran %engan sinar in&ramerah* +emberi!an in&ormasi"ang lebih ban"a! tentang a%a atau ti%a! a%an"a gugus &ungsi tertentu*

. Mass spectrometry 0 Pemboman ontoh %engan ele!tron %an

$en%ete!sian &ragmen mole!ul hasiln"a* +emberi!an in&ormasi tentangmassa mole!ul %an hubungan atom*

!. "#tra$io#et spectroscopy ("%) 0 Promosi ele!tron !e ting!at energi"ang lebih tinggi melalui $en"inaran1$ema$aran mole!ul %engan sinarultra2iolet* Keban"a!an memberi!an in&ormasi tentang a%an"a sistem!on)ugasi π %an a%an"a i!atan rang!a$ %ua %an rang!a$ tiga*


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SPE4TRU+ INTERPRETATIONPRO4ESS

5* Re ogni6e a pattern.7* Asso iate $atterns (ith physical parameters.

8* I%enti&" $ossible meanings# i*e* proposeexplanations.

On e a s$e trum is obtaine%# the main hallenge is toe9tra t the in&ormation it ontains in abstra t# or hi%%en&orm* This re:uires the re ognition o& ertain $atterns#the asso iation o& these $atterns (ith $h"si al$arameters# an% the inter$retation o& these $atterns interms o& meaning&ul an% logi al e9$lanations*


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E;E4TRO+AGNETI4 SPE4TRU++ost organi s$e tros o$" uses e#ectromagnetic energy, or radiationas the $h"si al stimulus*

Ele tromagneti energ" .su h as 2isible light/ has no %ete table massom$onent* In other (or%s# it an be re&erre% to as

• 'nergy (') > Energ" is %ire tl" $ro$ortional to &re:uen "# an%in2ersel" $ro$ortional to (a2elength# as in%i ate% b" the e:uationbelo(*

• re-uency ( )• a$e#ength ( λ )

' / h


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E??E4T O? E;E4TRO+AGNETI4 RA,IATIONON +O;E4U;ES

0raphics source: ade, r., .0. Organic Chemistry , 3th ed. &earson 'ducation Inc., 244


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5n IRSpectrum5 p#ot of 6 transmittance $s $i7rationa#

fre-uency in 8a$enum7ers (cm91

)

λ @ (a2elength υ @ &re:uen "

c @ s$ee% o& light in a 2a uum

c

υ λ

=1

λυ =c

)(000,10)(cm 1-

mwavenumber

µ λ υ ==

υ


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a$enum7ers

he higher the 8a$enum7er, the shorter the 8a$e#ength.

)(000,10

)(cm 1-m

wavenumber µ λ

υ ==


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5n IR Spectrum

he 8a$e#ength of IR radiation is in the 2.3923

micron range (compare to $isi7#e #ight in the !449

44 nm range).

he fre-uencies of IR radiation are more

con$enient#y e;pressed 7y a 8a$enum7er(cyc#es per cm), than 7y ν (cyc#es per .4 ; 14

cm).

υ


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In&rare% ra%iation is largel" thermal energ"*It in%u es stronger mo#ecu#ar $i7rations in o2alent bon%s#(hi h an be 2ie(e% as s$rings hol%ing together t(o masses#or atoms*


Speci


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=haracteristic %i7rationa#re-uencies of Bonds

Bonds are not rigid 7ut 7eha$e #ike a spring 8ith a mass ateither end.

*7ey >ooke?s a8: / 9k;

his gi$es rise to a characteristic fre-uency for the$i7ration:

massreduced

k

21π

υ =

mreduced = µ


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=haracteristic 8a$enum7er ofBonds=haracteristic 8a$enum7er for the $i7ration:

he 8a$enum7er is a@ected 7y

the masses of the atoms in the 7ond

the strength of the 7ond

Where M in amu

massreduced

k

c 21π

υ =

µ υ K

12.4=

M

massreduced == µ


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he stronger the 7ond, the higher the $i7rationa# fre-uency.

Stretching fre-uencies

= ≡ = A =/= A =9=

= ≡ A =/ A =9

= ≡ * A =/* A =9*=(sp)9> A =(sp 2 )9> A =(sp )9>

he #o8er the mass, the higher the $i7rationa# fre-uency.

Stretching fre-uencies for 7onds to car7on:A =9 A =9*


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um7er of %i7rationa# re-uenciesin a Mo#ecu#e

here are 3n-6 possi7#e $i7rationa# modes in a non#inearmo#ecu#e 8ith no symmetry

Symmetry reduces the num7er of possi7#e $i7rationa#modes.

ater has possi7#e $i7rationa# modes.

orma#dehyde has C.


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3IBRATIONA; +O,ES

4o2alent bon%s an 2ibrate in se2eral mo%es# in lu%ingstretching, rocking, and scissoring *

The most use&ul ban%s in an in&rare% s$e trum orres$on% tostret hing &re:uen ies# an% those (ill be the ones (e ll &o us on*



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TRANS+ISSION 2s* ABSORPTION

When a hemi al sam$le is e9$ose% to the a tion o& IRI0> # it an a7sor7 some &re:uen ies an% transmit the

rest* Some o& the light an also be re e te% ba ! to thesour e*

4hemi alsam$le

IRsour e

Transmitte%light

?rom all the &re:uen ies it re ei2es# the hemi alsam$le an a7sor7 .retain/ speci


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AN IR SPE4TRU+ IN ABSORPTION +O,E The IR s$e trum is basi all" a $lot o& transmitte% .or absorbe%/&re:uen ies 2s* intensit" o& the transmission .or absor$tion/*?re:uen ies a$$ear in the x -a9is in units o& in2erse entimeters.(a2enumbers/# an% intensities are $lotte% on the y -a9is in$er entage units*

The gra$h abo2e sho(s a s$e trum in a7sorption mo%e*


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AN IR SPE4TRU+ IN TRANS+ISSION +O,E

The gra$h abo2e sho(s a s$e trum in transmission mo%e*his is the most common#y used representation an% the one

&oun% in most hemistr" an% s$e tros o$" boo!s* There&ore (e (illuse this re$resentation*


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4;ASSI?I4ATION O? IR BAN,SIR ban%s an be lassi'e% as strong .s/# medium .m/# or 8eak %e$en%ing on their relati2e intensities in the in&rare% s$e trum* Astrong ban% o2ers most o& the y -a9is* A me%ium ban% &alls to abouthal& o& the y -a9is# an% a (ea! ban% &alls to about one thir% or less o&the y -a9is*


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IN?RARE, A4TI3E BON,SNot all o2alent bon%s %is$la" ban%s in the IR s$e trum* *n#y po#ar

7onds do so. hese are referred to as IR acti$e *

The intensit" o& the ban%s %e$en%s on the magnitu%e o& the dipo#emoment asso iate% (ith the bon% in :uestion>

Strongl" $olar bon%s su h as arbon"l grou$s .4@O/ $ro%u e strongban%s*

+e%ium $olarit" bon%s an% as"mmetri bon%s $ro%u e me%iumban%s*

Wea!l" $olar bon% an% s"mmetri bon%s $ro%u e (ea! or nonobser2able ban%s*


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IN?RARE, BAN, SCAPESIn&rare% ban% sha$es ome in 2arious &orms* T(o o& the most ommon

are narro8 an% 7road * Narro( ban%s are thin an% $ointe%# li!e a%agger* Broa% ban%s are (i%e an% smoother*

A t"$i al e9am$le o& a broa% ban% is that %is$la"e% b" O-C bon%s# su has those &oun% in al ohols an% arbo9"li a i%s# as sho(n belo(*


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IN?OR+ATION OBTAINE, ?RO+ IR SPE4TRA

• IR is most use&ul in $ro2i%ing in&ormation about the$resen e or absen e o& s$e i' functiona# groups *

• IR an $ro2i%e a mo#ecu#ar


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TCE ?INGERPRINT REGIONAlthough the entire IR s$e trum an be use% as a 'nger$rint &or the$ur$oses o& om$aring mole ules# the C44 9 1!44 cm 91 range is alle%the


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Some characteristic infrared absorption frequencies BOND COMPOUND TYPE F E!UENCY "N#E$ cm %& C%' a()anes *+,-%*./- and &0,-%&12- a()enes 0-*-%0-+- 3m4 and C'5C'* .&-%.*- and ..-%&--- *C5C'* ++-%.-- cis % C'5C' /2,%20- 364 trans % C'5C' ./,%.2, aromatic rin7s 0---%0&-- 3m4 and monosubst8 /.-%2&- and 20-%22- ortho %disubst8 20,%22-

meta %disubst8 /.-%2&- and 2,-%+&- 3m4 para %disubst8 +&-%+1- 3m4 a()9nes 00-- O%' a(coho(s or pheno(s 0*--%0/1- 3b4 C5C a()enes &/1-%&/+- 364 aromatic rin7s &,-- and &/-- 364 C:C a()9nes *&--%**/- 364 C%O primar9 a(coho(s &-,- 3b4 secondar9 a(coho(s &&-- 3b4 tertiar9 a(coho(s &&,- 3b4 pheno(s &*0- 3b4 a()9( ethers &-/-%&&,- ar9( ethers &*--%&*2,3b4and &-*-%&-2,3m4 a(( abs8 stron7 un(ess mar)ed; m$ moderate< 6$ 6ariab(e< b$ broad


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IR SPE4TRU+ O? A;KANESAl!anes ha2e no &un tional grou$s* Their IR s$e trum %is$la"s onl" 4-4an% 4-C bon% 2ibrations* O& these the most use&ul are the =9> 7ands(hi h a$$ear aroun% 444 cm 91* Sin e most organi mole ules ha2esu h bon%s# most organi mole ules (ill %is$la" those ban%s in their

s$e trum*



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IR s$e tra o& 5 5 'S

4 C bon%


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n 9pentane

4C 84C 74C 74C 74C 8

444 cm 91

1! 4 G1 3 cm 91

2D3492EC4cm 91

sat?d =9>


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4C 84C 74C 74C 74C 74C

n 9he;ane


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29methy#7utane(isopentane)


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2, 9 dimethy#7utane


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cyc#ohe;ane

no 1 3 cm 91

no +=>


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IR o& 5 ' 'S

@4 C bon%#


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19decene

E149E24G EE491444R=>/=>=/= 1C!491CD4

unsat?d=9>

4249

4D4cm 91


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!9methy#919pentene

E149E24G EE491444R=>/=>


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29methy#9197utene

DD49R 2 =/=>


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2, 9dimethy#9197utene

DD49R 2 =/=>

IR SPE4TRU+ O? A;KENES


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IR SPE4TRU+ O? A;KENESBesi%es the $resen e o& 4-C bon%s# al!enes also sho( shar$# me%iumban%s orres$on%ing to the =/= 7ond stretching $i7ration at abo1C4491 44 cm 91* Some al!enes might also sho( a ban% &or the @4-Cbon% stret h# a$$earing aroun% 4D4 cm 91 as sho(n belo(* Co(e2er#this ban% oul% be obs ure% b" the broa%er ban%s a$$earing aroun%8DDD m -5 .see ne9t sli%e/



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IR s$e tra B' H' ' s

@4 C bon%#


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h


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ethy#7en ene

CE4914,

49 4 mono9

1344 G 1C44

Ben enering

4449144

cm 91

"nsat?d =9>

9 #


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o 9;y#ene

39

4ortho

9 #


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p 9;y#ene

D149

D!4(m)para

m 9;y#ene


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m 9;y#ene

meta

CE49 14,

349D14(m)

styrene


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styrene

no sat?d =9>

E149E24 GEE491444

R=>/=> 2 mo

1C!4=/=


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p 9


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p 9methy#styrene

para

IR SPE4TRU+ O? A;KYNES


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; The most $rominent ban% in al!"nes orres$on%s to the car7ocar7on trip#e 7ond * It sho(s as a shar$# (ea! ban% at about2144 cm 91* The reason it s (ea! is be ause the tri$le bon% is not2er" $olar* In some ases# su h as in highl" s"mmetri al al!"nes#it ma" not sho( at all %ue to the lo( $olarit" o& the tri$le bon%asso iate% (ith those al!"nes*

Terminal al!"nes# that is to sa" those (here the tri$le bon% is atthe en% o& a arbon hain# ha2e 4-C bon%s in2ol2ing the sp

arbon .the arbon that &orms $art o& the tri$le bon%/* There&orethe" ma" also sho( a shar$# (ea! ban% at about 44 cm 91

orres$on%ing to the 4-C stret h*

Internal al!"nes# that is those (here the tri$le bon% is in themi%%le o& a arbon hain# %o not ha2e 4-C bon%s to the sp

arbon an% there&ore la ! the a&orementione% ban%*

The &ollo(ing sli%e sho(s a om$arison bet(een anuns"mmetri al terminal al!"ne 5-o t"ne/ an% a s"mmetri al

IR SPE4TRU+ O? A;KYNES


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0raphics source: ade, r., .0. Organic Chemistry , Cth ed. &earson &rentice >a## Inc., 244C

IR SPE4TRU+ O? A NITRI;E


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IR SPE4TRU O? A NITRI;EIn a manner 2er" similar to al!"nes# nitriles sho( a $rominent ban%aroun% 2234 cm 91 ause% b" the = trip#e 7ond * This ban% has ashar$# $ointe% sha$e )ust li!e the al!"ne 4-4 tri$le bon%# but be ausethe 4N tri$le bon% is more $olar# this ban% is stronger than in al!"nes*



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Ben6"l iso "anate


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IR s$e tra 5 =*>* S G ' >'RS

4 O bon% 1434912 3 (7) cm 91

5 o ROC 5DJD

7 o ROC 55DD

8 o ROC 55JD

ethers 5D D-55JD

O C bon% 2449 C!4 (7)


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197utano#


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4C 84C 74C 74C 7-OC

=9* 1 o

2449 C!4(7) *9>


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297utano#


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=9* 2 o*9>

tert 97uty#


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a#coho#

=9* o*9>

methy# n 9propy#


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ether

no *99>

=9*ether

IR SPE4TRA O? A+INES


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The most hara teristi ban% in amines is %ue to the 9> 7ond stretch # an%a$$ears as a (ea! to me%ium# some(hat broa% ban% .but not as broa% as the O-C ban% o& al ohols/* This ban% is $ositione% at the le&t en% o& the s$e trum# in therange o& about 244 9 C44 cm 91*

Primar" amines ha2e t(o N-C bon%s# there&ore the" t"$i all" sho( t(o s$i!esthat ma!e this ban% resemble a molar tooth* Se on%ar" amines ha2e onl" one N-C bon%# (hi h ma!es them sho( onl" one s$i!e# resembling a anine tooth*?inall"# tertiar" amines ha2e no N-C bon%s# an% there&ore this ban% is absent&rom the IR s$e trum altogether* The s$e trum belo( sho(s a se on%ar" amine*



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=m 91=5RB* J =*M&*" KS


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5 5D 5 DD 5 D 5 8J 5 7J 5 5J 5 5D

Anh"%ri%e.ban% 5/

A i%hlori%e

Anh"%ri%e.ban% 7/

Ester Al%eh"%e Ketone 4arbo9"lia i%

actors hat InLuence the =/* Stretching %i7ration

;o(ering o& the &re:uen " in a 7&rom the base 2

=on ugation '@ects

Ring Si e '@ects


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Su7stituent '@ects

The ele tron-(ith%ra(ing e e t remo2es ele tron &rom thearbon o& the 4@O bon%* This remo2al is om$ensate% &or b

tightening o& the π bon% an% lea%s to an in rease in theabsor$tion &re:uen "*

>ydrogen9Bonding '@ects

C"%rogen bon%ing to a arbon"l grou$ lengthens the 4@O bon%an% lo(ers the stret hing &or e onstant K # resultingabsor$tion &re:uen "*

IR SPE4TRU+ O? A;,ECY,ES AN, KETONES


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4arbon"l om$oun%s are those that contain the =/* functiona#group * In al%eh"%es# this grou$ is at the en% o& a arbon hain#(hereas in !etones it s in the mi%%le o& the hain* As a result# the

arbon in the 4@O bon% o& al%eh"%es is also bon%e% to another arbon

an% a h"%rogen# (hereas the same arbon in a !etone is bon%e% to t(oother arbons*

Al%eh"%es an% !etones sho( a strong# $rominent# sta!e-sha$e% ban%aroun% 1 14 9 1 24 cm 91 .right in the mi%%le o& the s$e trum/* Thisban% is %ue to the high#y po#ar =/* 7ond * Be ause o& its $osition#sha$e# an% si6e# it is har% to miss*

Be ause al%eh"%es also ontain a 4-C bon% to the sp 7 arbon o& the4@O bon%# the" also sho( a $air o& me%ium strength ban%s $ositione%about 2 44 an% 2D44 cm 91* These ban%s are missing in the s$e trumo& a !etone be ause the sp 7 arbon o& the !etone la !s the 4-C bon%*

The &ollo(ing sli%e sho(s a s$e trum o& an al%eh"%e an% a !etone*Stu%" the similarities an% the %i eren es so that "ou an %istinguishbet(een the t(o*


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IR SPE4TRU+ O? A;,ECY,ES AN, KETONES


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297utanone


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=/*

N1 44

(s)

IR SPE4TRU+ O? A 4ARBO Y;I4 A4I,


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A arbo9"li a i% &un tional grou$ ombines the &eatures o& al oholsan% !etones be ause it has both the *9> 7ond an% the =/* 7ond

There&ore arbo9"li a i%s sho( a 2er" strong an% broa% ban% o2eringa (i%e range bet(een 2!44 an% !44 cm 91 &or the O-C stret h* At the

same time the" also sho( the sta!e-sha$e% ban% in the mi%%le o& thes$e trum aroun% 1 14 cm 91 orres$on%ing to the 4@O stret h# an%aroun% 1 2491214 cm 91 .me%ium intensit"/ orres$on%ing to the 4-Ostret h*



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'S 'RS


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IR SPE4TRU+ O? A+I,ESThe ami%e &un tional grou$ ombines the &eatures o& amines an%


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The ami%e &un tional grou$ ombines the &eatures o& amines an%!etones be ause it has both the 9> 7ond an% the =/* 7ond *

There&ore ami%es sho( a 2er" strong# some(hat broa% ban% at the le&ten% o& the s$e trum# in the range bet(een 144 an% 344 cm 91 &oN-C stret h* At the same time the" also sho( the sta!e-sha$e% ban% in

the mi%%le o& the s$e trum aroun% 1 14 cm 91 &or the 4@O stret h* As(ith amines# $rimar" ami%es sho( t(o s$i!es# (hereas se on%ar"ami%es sho( onl" one s$i!e*



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5cid =h#orides


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itro =ompounds


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Su#fur =ompounds


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Mercaptans R9S9>


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= E> 12


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=9> unsat?d Gsat?d

1344 G1C447en ene

mon= E> 12 + = C> 3 /

9= >

isopropy#7en ene

n 9

n 9propy#7en ene


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= D> C


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=9>unsat?d

1344,1C447en ene

mono

= D> C + = C> 3 / = 2 >

pheny#acety#ene

44≡ =9>

= ! > D


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1C!491CD4

=/=

DD49E44R 2 =/=> 2

"nst?d


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Whi h om$oun% is thisa/ 7-$entanoneb/ 5-$entanol

/ 5-bromo$entane%/ 7-meth"l$entane

19pentano#


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What is the om$oun%a/ 5-bromo$entaneb/ 5-$entanol

/ 7-$entanone%/ 7-meth"l$entane

29pentanone

In a


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H2C C

HCH 2

CH 3CH 3

CH3CH

2CH

2CH

2CH

3

H2C

H2C

CH 2 CH 2 CH 2 CH 3

biphenyl allylbenzene 1,2-diphenylethane

o-xylene n-pentane n-butylbenzene

A

B

C

D

E

F


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7


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8


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J


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1-Organic Structure Determination

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