The Carbon Group: Exercises and Cases studies
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Cases studies: 1. Simethicone 2. Germanium supplements
Exercises
1. Draw
the Lewis structures of the following silicon compounds and compare them with
their carbon analogues.
(a)
Silicon dioxide
(b)
Silicon tetrachloride
(c)
Silane
(d)
Trichlorosilane
2. Calculate
the ΔEN for all bonds in the
following silicon compounds and compare these values with the corresponding
carbon bonds.
(a)
Silicon tetrachloride
(b)
Silane
(c)
Trichlorosilane
3. Research
and calculate the bond length in the following compounds and compare them with
their carbon analogues.
(a)
Silane
(b)
Germane
(c)
Germanium tetrachloride
(d)
Silicon tetrachloride
(e)
Silicon dioxide
Cases
studies
1. Simethicone
Simethicone is a silicon-based antifoaming agent that can be
found in a variety of formulations.
(a)
Describe the chemical structure of
simethicone.
(b)
Research its mode of action and route through
the human body.
(c)
Identify clinical applications for
simethicone.
(d)
Typical oral suspension used for infants
contain simethicone 40 mg/ml. Calculate the weight/volume percentage (%w/v).
2. Germanium supplements
Organic germanium is sold as a dietary supplement and contains
mainly bis-carboxyethyl germanium sesquioxide. Despite many positive health
claims, several severe side effects including kidney failure have been
reported. These side effects are often explained by toxic impurities, and
therefore information on the testing procedures can often be found on the
packaging. Typical information would read as follows: ‘Analysis performed
includes identification by infrared spectroscopy and solubility testing. The
purity has been identified by acid group titration and the absence of inorganic
germanium has been confirmed by a colour limit test’.
(a)
Draw the chemical structure of
bis-carboxyethyl germanium sesquioxide.
(b)
What is the toxic impurity typically found in
these preparations?
(c)
What is the solubility of bis-carboxyethyl
germanium sesquioxide?
(d)
Describe the results you would expect from the
infrared analysis.
(e)
Research a method for the acid base titration
mentioned.
(f)
Research the colour limit test for inorganic
germanium.
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