Trimethyloxonium tetrafluoroborate

Colorless, crystalline solid

Fixed

202-203 ° C

Decomposition in water

Risk

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Trimethyloxonium, [(CH3) 3O BF4 - ] is a strong alkylating agent that belongs to the Meerwein salts ( named after the German chemist Hans Meerwein ). Occasionally, it is also simply referred to as Meerwein salt, but this is not clear.

Representation and extraction

The trimethyloxonium tetrafluoroborate can be obtained by the reaction of dimethyl ether with methyl iodide and silver tetrafluoroborate. First, in this case the ether reacts with methyl iodide to Trimethyloxoniumiodid. This is then reacted in situ with silver tetrafluoroborate with precipitation of silver iodide on trimethyloxonium tetrafluoroborate.

Properties

In trimethyloxonium is a colorless solid that sublimes at 202-203 ° C. It reacts violently with water to form an acidic solution.

Reactions

Trimethyloxonium decomposes in a violent reaction in water to dimethyl ether, methanol and tetrafluoroboric.

There is a very strong methylating agent which can be applied for example in the synthesis of Fischer carbenes. The lithium compound formed as an intermediate is methylated here to form a Fischer carbene with trimethyloxonium.