Chemistry Reference
In-Depth Information
Fig. 9.5
Synthetic pathways of the substances A-F. R1: Reactions with the dichromate reagent.
R2: Reactions with sodium hydroxide solution (ester hydrolysis). R3: Reactions with sulfuric acid
(ester synthesis)
- It has to be explained that one can find out the number of carbon atoms in a mole-
cule with the help of the
13
C-NMR spectrum: Every signal in the spectrum can be
matched with a carbon atom of the molecule. Carbon atoms with the same substi-
tuents give the same signal (the signals coincide at the same spot of the spectrum).
- Regarding the mass spectrometry students have to know that a mass spectrum
gives information about the molecular mass and about the masses of molecular
fragments.
- The theoretical background information of the spectroscopic methods can be
discussed at this stage or delivered later as needed.
The spectral analysis (Fig.
9.6
) will be explained using the example substance
A (ethanol):
The molecular mass 46 u can be extracted from the mass spectrum. This leads to
three structural hypotheses H1-H3 (taking into account the assumed atomic masses
and bonding rules):
