Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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tert-butanol : (CH3)3COH
ethanol : CH3CH2OH
methanol : CH3OH
bleach : NaClO
Class:
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elem=C,Cl
organic
Summary:
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Formation of hypochlorite esters is very easy. With many alcohols, it is
possible to make hypochlorite esters. These esters are very unstable and easily
explode or burn very fiercely when ignited.
All experiments, described here are quite dangerous, use good protection of the
eyes and keep test tubes wrapped in a thichk layer of towels. Do not scale up!
Description:
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Formation of methyl hypochlorite:
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This is a very spectacular experiment, but you need to use a thick-walled test
tube, wrapped in a thick layer of towel!!!
- In a thick-walled test tube, put 3 to 4 ml of strong bleach with 12-15%
active chlorine.
- In a separate test tube put a little under 1 ml of acetic acid (0.75 ml or
so).
- To the acetic acid, add half a ml of methanol and swirl such that the liquids
mix well.
- Add the acetic acid/methanol mix to the bleach in two steps and swirl the
test tube after each addition.
When this is done, then on swirling a colorless gas is produced. The formation
of the gas is accompanied by a fairly loud bubbling noise. Big bubbles of gas
escape from the liquid. There is no strong formation of heat.
When swirling does not result in formation of gas anymore, then wrap the test
tube in a thick layer of towel. Keep the test tube at an angle of 45 degrees
and then keep a flame in front of the open end of the test tube. When this is
done, a remarkably powerful explosion occurs. Only the gas explodes, the liquid
is not altered. The sound of the explosion is thundering loud! Given the fact
that only appr. 20 ml of gas explodes in the test tube, this is quite
remarkable. Methyl hypochlorite has no practical a
Preparation of ethyl hypochlorite:
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- Take 4 ml of strong bleach with 12-15% active chlorine. Put this in test tube
A.
- Take 1 ml of acetic acid (80%) and put this in test tube B.
- Take 0.5 ml of ethanol (96%, denatured with 1% MEK) and add this to test tube
B. Swirl the contents of test tube B.
- Pour the contents of test tube B in test tube A. Do this not at once, but add
in 4 steps. After each time swirl the test tube to mix the solutions.
A yellow oil separates and remains floating on the aqueous layer. The layer
only has a thckness of 3 mm or so. The yellow oil is very volatile and quickly
disappears (in 10 minutes or so, all of it is gone). The oil has a strong and
pungent smell, not very pleasant.
Using a glass pasteur pipette, take some of the oil and put it on a watch
glass. Immediately keep a small flame near the oil. The oil catches fire very
easily and burns explosively violently with a WHOOSH sound. If you wait too
long with igniting the oil, then nothing is left, it evaporates very easily.
The experiment can be carried out at room temperature (15 - 25 C). Test tube A
should be cooled under a running tap with water of appr. 15 C when the contents
of test tube B is added. No excessive heat was observed, but the mix can heat
up somewhat.
Preparation of tert-butyl hypochlorite:
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- Take 7 ml of strong bleach with 12-15% active chlorine. Put this in test tube
A.
- Take 1 ml of acetic acid (80%) and put this in test tube B.
- Take 1 ml of tert-butyl alcohol and add this to test tube B. Swirl the
contents of test tube B.
- Pour the contents of test tube B in test tube A. Do this not at once, but add
in 4 steps. After each time swirl the test tube to mix the solutions.
In this experiment, a layer of more than 5 mm of oily yellow liquid is
obtained. This liquid is much less volatile than ethyl hypochlorite.
Using a glass pasteur pipette, some of this liquid can be put on a watch glass
and ignited. It can be lighted very easily and burns fiercely with a sooty
flame. The smell of the soot is the same as that when chlorinated alkanes are
burnt.