IR Spectroscopy Wu L.M. Salesians of Don Bosco Ng Siu Mui Secondary School

HKAL ( * * )

HKAL Syllabus: Instrumentation Analysis An awareness that spectroscopic methods such as infra-red spectroscopy and nuclear magnetic resonance (NMR) can provide information about the structure of a molecule.

nuclear magnetic resonance (NMR) NMR spectroscopy typically gives the hydrocarbon fragments

infra-red spectroscopy the most useful information obtained from an IR spectrum is what functional groups are present within the molecule

Topic: Use of infra-red (IR) spectrum in the identification of functional groups IR spectrum and its use in the identification of the following groups: C-H O-H N-H C=C C C=O and C N (Instrumentation is not required)

Suggested Experiments / Activities Inspection of IR spectrum of organic compounds.

IR Spectroscopy Instrument m/

7 IR Characteristic peaks 7 vibrational movement (covalent bond ) 7 (peak)

IR spectrum analysis (infrared spectroscopy) ( )

/ cm -1 Alkane, C – H 2850 – 2960 Alkene, =C – H 3020 – 3100 Alkene, C=C 1650 – 1670 Alkyne, C – H 3300 Alkyne, – CC – 2100 – 2260 Alcohol, O – H 3400 – 3640 Alcohol, C – O 1050 – 1150 Carboxylic, O – H Amine, N – H 3310 – 3500 Amine, C – N 1030, 1230 Carbonyl, C=O 1670 – 1780 Nitrile, CN 2210 – 2260

Characteristic Infra-red Absorption Wave number Ranges (Stretching modes) HKAL

IR spectrum

IR Real Spectrum

IR Spectroscopy Experiment

Learning time………. Are you read to examine some IR Spectrum?

Alkane C-H

Alkene C=C =C-H

Alkynes C C C-H 3300

Alcohol O-H

Alkanoic acid O-H

Amine N-H

Ketone C=O

Aldehyde C=O

Nitrile CN C N

Test time………. Are you read to identify one unknown IR Spectrum?

Ester Quick Test C=O C-H

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