Organic chemistry 2 lesson 2

a
CHM 2211 LessonZ4: IR Spectroscopy <&

1. MATCH each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions
occur. Place the letter of the region in the blank to the left of the bond type.

(a) 4000-2500 cm? b) 2500-2000 cm™ ¢) 2000-1500 cm™ d) below 1500 cm™!


L= C-C, C-0, C-N, and C-X single bond vibrations

. C=0, C=N, and C=C bond absorptions

A N-H, C-H, O-H stretching and bending motions

& C=C, C=N triple bond stretching vibrations

2. MATCH each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions
occur. Place the letter of the region in the blank to the left of the bond type.
C-vw Oo-w n-H C=c C=N C=0 C=C - o-C, C-x
(2) 4000-2500 cm” b) 2500-2000 cm? ¢) 2000-1500 cm? d) below 1500 cm™


A D H3;CC=CCH,CH,CHs3


A © CH;CH,OCH(CHs)2

A (CH3)CHCH,C(CH3)3

3. Provide the structure of three (3) compounds with the molecular formula C;sHsO that give an absorption peak at 1600-
1400 cm! in the infrared spectrum, but no significant peaks at 3000-3600 cm™ or at 1650-1750 cm™. \u - S-4zy
No OV no C=0




4\6/\ //\/é\ /Q/é\ )\--/


4. Provide the structure of four (4) compounds with the molecular formula CsH;0O which give a strong absorption peak
at 1700-1740 cm™ in the infrared spectrum but no significant peaks at 1600-1640 cm™.
c=0 no <= ‘Ho =2 6-5=)


o o ) 8 <o

“)W /\l\/\ )\( “/“Y\ “)'\/k /\(\

o


5. Provide a brief explanation to account for the observation that but-1-yne gives a significantly stronger peak at ~1250
cm! in the infrared spectrum than but-2-yne. Yerminal

BDonds onla Occur When bond treakes oo A:po\e_ oS % Viorades,

iNnrernal Allyne I3 synmedric. SO NO pedle
Feronino) Q\ht'\e Nag aa =C-W Siredch

, 6. The chemical formula of the compound that gave rise to the following infrared spectrum is C¢H140. Label three peaks
in the following spectrum with the bond that gives rise to them, and identify the functional group that is present in the
compound. \Mp = ¢

Micrometers .
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gn \ f ] f .;'}l' \ ¥
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E 30
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10 = ¥ 393
0
000 600 AN W00 2400 2000 1800 I T0 1200 16m 800 600 40
Wavenumber
(cm 1


Functional group = O\ covol

7. The chemical formula of the compound that gave rise to the following infrared spectrum is CsH100,. Label three
peaks in the following spectrum with the bond that gives rise to them, and identify the functional group that is present
in the compound Mo =\

Micrometers
i 32 3 4 $ 4 1oty 0. W B B Y 2
Rl LN
,— » \ / Y o Q /N \ ," o A \ f 3\ A / \\\ f\\'
oM \ / / 1\ N \r "
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y \» f =0
1t s? v c’ T

Ll —
Sinl Vanr T H N pETEN et U] (LU [y (e 11X lian) s NI Y

Wavenumbus (¢ 1)



Functional group = Corvonylic. OCIA

8. The chemical formula of the compound that gave rise to the following infrared spectrum is C4HsNO. Label three
peaks in the following spectrum with the bond that gives rise to them and identify the functional group that is present
in the compound.
‘o= |
Micpumeten %
s b} 4 b 6 1 5 9 i 1) [N 13 »
L A A A A A " L A A A Y S TN SIS


" ~ “. ;/—-\\\ ~/ A R p—n—— \ P AT N < ye s T


Y] v \ |' \ |J \‘ r /\ ./ 25
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= (. I q I \ |
2w | f { \ 1
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P fEE
3 s \ \ |
g {1 | il
E- 3 ¥
1 \ |
Sh" Se i || \/v
o ¥e =20 Stabl vwzed oy N
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U W i) v 2ua T ¥, 10dry L 139 bowns Ny W A

Wnenunather iem N



Functional group = aide,