From Interpreting Organic Spectra

We have now seen how to identify functional groups by infrared spectroscopy and to find the molecular weight, halogen content and structural features of a molecule by mass spectrometry. If we use both techniques on a sample, then we can substantially extend the range of molecules we can identify. Both infrared spectroscopy and mass spectrometry can identify almost any molecule by comparison with a spectrum of the authentic material, but when working entirely with unknowns it is often difficult to distinguish isomers. The substances whose spectra you are given are generally simple ones, where isomerism is not a problem, so you should be able to identify each sample from its spectra.

1.


Sample 3.1

2.


Sample 3.2

3.


Sample 3.3

4.


Sample 3.4

5.


Sample 3.5

6.


Sample 3.6

7.


Sample 3.7

8.


Sample 3.8

9.


Sample 3.9

10.


Sample 3.10

Answers

1.

Propan-2-one (acetone)

2.

Ethanol

3.

2-Bromoethanol

4.

Acetonitrile

5.

Benzaldehyde

6.

Ethanoic acid anhydride (acetic anhydride)

7.

Ethanoic acid (acetic acid)

8.

Methyl acetate

9.

Chloroacetonitrile

10.

Pentan-3-one


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Infrared (IR) spectrometers measure the wavelength and intensity of the absorption of infrared light by a sample.
Mounting Compounds
Mounting compounds are used to encapsulate specimens of a metal, ceramic, minerals, biomaterials or other material to allow grinding, polishing and other sample preparation for analysis using microscopes, hardness testers or spectrometers. Mounting compounds are in the form of compression mounting resins (powders, pellets or preforms) or liquid resins.
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Mounting presses and equipment are used to encapsulate specimens of a metal, ceramic or other material with a mounting compound to allow grinding, polishing and other sample preparation for analysis using microscopes, hardness testers or spectrometers. Mounting pressing, vacuum impregnation and cold casting are techniques used in mounting metallographic or material samples.

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