Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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dichloromethane : CH2Cl2
methanol : CH3OH
triethylamine : N(CH2CH3)3
thionyl chloride : OSCl2
Class:
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elem=C,S,Cl
organic
Summary:
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Triethylamine frequently is used in reactions, where thionyl chloride is used,
in order to capture any HCl formed in the reaction. However, when the only
reactive compounds are thionyl chloride and triethylamine, then these two
compounds react by themselves, giving rise to formation of black material,
which sticks to the glass and is difficult to remove.
Description:
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Add a few drops of thionyl chloride to a few drops of triethylamine: A VERY
VIOLENT reaction occurs. As soon as the thionyl chloride comes in contact with
the triethylamine, a plume of black soot-like solid erupts from the test tube
and a very peculiar smell can be observed (not really pungent, but somewhat
burnt).
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Dissolve a few drops of thionyl chloride in 2 ml of methylene chloride.
Dissolve a few drops of triethylamine in another 2 ml of methylene chloride.
Mix the two liquids: As soon as the liquids are mixed, the resulting liquid
becomes yellow. Within a minute or so, the liquid darkens from yellow through
shades of orange, red and red/brown, until it almost becomes black. The liquid
also heats up, the methylene chloride boils for a brief moment, but this
immediately stops again.
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Dissolve a few drops of thionyl chloride in 2 ml of methylene chloride.
Dissolve a few drops of triethylamine in a mix of 1 ml of methylene chloride
and 1 ml of methanol.
Mix the two liquids: Now the resulting liquid remains colorless. There is some
heating of the liquid, but no visible reaction occurs. What happens is that the
thionylchloride reacts with the methanol, and the HCl produced in this reaction
is captured by the triethylamine.
Apparently, when methanol is present, the reaction with methanol is
sufficiently fast, such that the reaction of thioyl chloride with triethylamine
does not occur, the thionyl chloride is captured before it can react.
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WARNING: Do not mistake triethylamine with triethanolamine in this experiment.
NEVER EVER mix thionyl chloride with triethanolamine in a home lab!!!! This mix
may produce a very dangerous nitrogen mustard, which is an extreme blistering
agent!