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INTERPRETATION OF

INFRARED SPECTRA

  GUIDED BY: PRESENTEDBY:

Dr.Sk.Abdul Rehman R.Keerthi  M.Pharm, Ph D M.Pharm 1t !ear

  DEPARTMENT: Pharmaceutical analysis

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  Outline"Feature #$ an ideal IR S%e&trum

In$#rmati#n uld be #btained

Re'uirement $#r the inter%retati#n

(eneral rule #$ inter%retati#n

Illutrati#n

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Feature #$ an IRS%e&trum

Ab#r%ti#n )*and+ %e&trumS%e&trum beteen %er&ent tranmittan&e )- T+

and ae number ) ύ)

/ae number ) ύ) re%reent $re'uen&! ) υ) #$ IR

ab#r%ti#n T# re0i#n #$ ab#r%ti#n

  F(R )233341533 &m41+ Identi6&ati#n #$ 0r#u%

  FPR )15334233 &m41+ M#le&ular 6n0er%rint

)S%e&tral mat&hin0+

Nature )Intenit! and Sha%e+ #$ %e&tral band  Str#n0 )+, medium )m+, eak )+7 *r#ad andNarr#

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Di8erent t!%e #$ IR*and

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In$#rmati#n Obtained $r#m an9nkn#n IR S%e&tra

  IR i m#t ue$ul in %r#idin0 in$#rmati#nab#ut the %reen&e #r aben&e #$ %e&i6&

functional groups (FGR)

  IR &an %r#ide a molcular !ngrprint that &an be ued $#r the identi6&ati#n #$am%le )FPR+

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Inter%retati#n #$ S%e&traS%e&tral Re'uirement

 The %e&trum mut be ade'uatel! re#led and #$ade'uate intenit!.

 The %e&trum h#uld be #$ a %ure m%#und.

 The %e&tr#%h#t#meter h#uld be &alibrated #that the band are #bered at their %r#%er$re'uen&ie #r aelen0th.

 The meth#d #$ am%le handlin0 mut be %e&i6ed.

I$ a #lent i em%l#!ed, the #lentn&entrati#n, and the &ell thi&kne h#uld beindi&ated.

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C#rrelati#n Chart and Table

9

O-H 3400&m41 C≡C 2150&m41

N-H 3400&m41

C=O 1715&m41

C-H 3000&m41 C=C 1650&m41

C≡N 2250&m41 C-O 1100&m41

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Typical Infrared A!"rp#i"nTypical Infrared A!"rp#i"n

$e%i"n!$e%i"n!

2&5 4 5 5&5 6&1 6&5 15&4

4000 2500 2000 1'00 1650 1550 650

($)*+)NC, c.-1/

A))NTH  

./

O-H C-H

N-H

C=O C=Nery

fe

and!

C=C

C-ClC-O

C-N

C-C=C=,

CON/

C N

C C

N=O N=O8

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 A!"rp#i"n $e%i"n!

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A) A+)A) A+):;- 10 c.-1/

T

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Sim%le A%%r#a&h t# the Anal!i #$ S%e&trumat a (lan&e

) (eneral Rule+

:##k i$ &arb#n!l 0r#u% i %reent;...... The

C341??3 &m41 

If "#$ is prsnt, &he&k $#r the %reen&e #$

$#ll#in0 0r#u%.....

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%ci&s($')

a roa& an& nar *+,,'-+,, cm'. 

%mi&s)N4@+ medium ab#r%ti#n near 233 &m41

 B #metime d#uble di% ith e'uialent hale

Estr)C4O+

tr#n0 ab#r%ti#n near 13341333 &m41. 

%n/0&ri&s)&4#+

(ie t# C4O ab#r%ti#n near 1=1341?3 &m41

%l&/0&(C4@+

 h# t# eak ab#r%ti#n near >=53 and >53&m41.

1tons)C4R+

I$ n#ne #$ the ab#e i %reent, n$#rm the%reen&e #$ ket#ne

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If "#$ is asnt,

%lco/ols an& P/nols: Che&k $#r O4@,h# br#ad ab#r%ti#n near 233433 &m41.n6rm thi b! 6ndin0 C4O near 1334

1333&m41.

%mins: N4@ tret&h, h# mediumab#r%ti#n near 233 &m41  )1O  > band, >O41 band+

Et/rs: C4O near 13341333&m41,and al#aben&e #$ O4@ near 233&m41

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Doul on&s an& 2 or %romatic ring:

 

 C

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Nitro groups

 T# ab#r%ti#n at 1?334153 &m41 B 134133 &m41

0&rocarons 

  N#ne #$ the %re&edin0 i $#und

 

 Ma#r ab#r%ti#n are in C4@ re0i#n near 333 &m41

 

Ger! im%le %e&trum

 

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Illustrations

 Takin0 eHam%le #$ dru0

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Re$eren&e www2.ups.edu/faculty/hanson/pectroscopy/ IR / IRInterpretation.htm

chemwi!i.ucda"is.edu # ... # $nfraredpectroscopy 

chemistry.ore%onstate.edu/courses/ch&'()*'*/ch&'2/irinterp.htm

infrared .als.l+l.%o"/,-Manual/ IR  Interpretat ion.pdf 

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