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Master Program (S2) of Chemistry

University of Halu Oleo

Infrared Spectroscopy

Fitri Handayani Hamid (G2L121004)

© 2021, October

Elusidasi Struktur Molekul:

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Pendahuluan

Infrared spectroscopy (IR spectroscopy) is the spectroscopy that deals with the infrared region of the electromagnetic spectrum

IR can be used to identify and determine the functional groups of a molecule.

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Organic Molecules

1. Aliphatic Hydrocarbons

nonane

A

B

C

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2. Aromatic Compounds

Organic Molecules

Out-of-plane bending vibrations of aromatic compounds

3000 cm-1

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3. Oxygen-Containing Compounds

Organic Molecules

2700 cm-1

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4. Nitrogen-Containing Compounds

Organic Molecules

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5. Halogen-Containing Compounds

Organic Molecules

2800-2970 cm-1

C-H aliphatic

400-800 cm-1

C-Cl

Source: https://webbook.nist.gov/

1-chloro-pentane

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Organic Molecules

Identification

Citronellal

2800 - 2700 cm-1

C-H aldehid

1740 – 1720 cm-1

C=O aldehida

3000 - 2900 cm-1

C-H Alifatik

1470 cm−1

CH3 asimetris

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Organic Molecules

Vanilin

O-H

3550 cm-1

3000 cm-1

C-H aromatik

2800-2700 cm-1

C-H aldehide

1790 dan 1740 cm−1

C=O aldehida

1600-1430 cm−1

C=C aromarik

1300-1100 cm−1

C-O Phenol/Ether

Identification

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Cyclohexanone

C=O

C-H (sp3) stretch

 2,950 cm-1

 2,850 cm-1

1,750 cm-1 

Cyclohexanol

3350 cm-1

O-H stretch

1100 cm-1

C-O stretch

1470 cm-1

C-H bend

C-H (sp3) stretch

 2,950

 2,850

Oxygen Identification

Source: https://webbook.nist.gov/

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  • O–H stretch, hydrogen bonded 3500-3200 cm-1
  • C–O stretch 1260-1050 cm-1 (s)

Ethanol

O-H stretch

C-H (sp3) stretch

C-O stretch

Cyclohexanol

O-H stretch

C-H (sp3) stretch

C-O stretch

C-H bend

Oxygen Identification

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C-H (sp3) stretch

C-H (sp3) stretch

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  • N–H stretch 3400-3250 cm-1
    • 1° amine: two bands from 3400-3300 and 3330-3250 cm-1
    • 2° amine: one band from 3350-3310 cm-1
    • 3° amine: no bands in this region
  • N–H bend (primary amines only) from 1650-1580 cm-1
  • C–N stretch (aromatic amines) from 1335-1250 cm-1
  • C–N stretch (aliphatic amines) from 1250–1020 cm-1
  • N–H wag (primary and secondary amines only) from 910-665 cm-1

IR Spectroscopy Tutorial: Amines

Source: https://www.orgchemboulder.com/Spectroscopy/irtutor/aminesir.shtml

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1-Phenyl-2-propene

Organic Molecules

Aromatic Identification

690-710, 730-770

mono

3000-3100 cm-1

C-H aromatic

2800-2970 cm-1

C-H alkana

1430-1600 cm-1

C=C stretching aromatic

1600-1680 cm-1

C=C stretching Aliphatic

Source: https://webbook.nist.gov/

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o-ethyl- Aniline

Organic Molecules

Aromatic Identification

735-770

ortho

3000-3100 cm-1

C-H aromatic

1430-1600 cm-1

C=C stretching aromatic

2800-2970 cm-1

C-H alkana

1615 cm-1

NH amine

3400-3300 cm-1

NH (1°)

Source: https://webbook.nist.gov/

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m-Methylbenzonitrile

Organic Molecules

Aromatic Identification

690-710, 750-810

meta

3000-3100 cm-1

C-H aromatic

2800-2970 cm-1

C-H alkana

2260-2240 cm-1

C≡N Aliphatic

1430-1600 cm-1

C=C stretching aromatic

Source: https://webbook.nist.gov/

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p-xylene

Organic Molecules

Aromatic Identification

810-840(m)

para

3000-3100 cm-1

C-H aromatic

2800-2970 cm-1

C-H alkana

1430-1600 cm-1

C=C stretching aromatic

Source: https://webbook.nist.gov/

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Organic Molecules

Halogen-Containing Compounds

1-chloro-pentane

2800-2970 cm-1

C-H aliphatic

400-800 cm-1

C-Cl

Source: https://webbook.nist.gov/

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1-Amino-2-butanol

2-Amino-1-butanol

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THANK YOU

Fitri Handayani Hamid (G2L121004)

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