Trimethyloxonium tetrafluoroborate is the

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...

with the formula . (It is sometimes called "Meerwein's salt" after

Hans Meerwein Hans Meerwein (May 20, 1879 in Hamburg, Germany – October 24, 1965 in Marburg, Germany) was a German chemist. Several reactions and reagents bear his name, most notably the Meerwein–Ponndorf–Verley reduction, the Wagner–Meerwein rearran ...

.Meerwein's salt classically referred to

triethyloxonium tetrafluoroborate Triethyloxonium tetrafluoroborate is the organic oxonium compound with the formula CH3CH2)3OF4. It is often called Meerwein's reagent or Meerwein's salt after its discoverer Hans Meerwein. Also well known and commercially available is the relat ...

. However, in recent years, the trimethyloxonium salt has also been called Meerwein's salt.) This salt is a strong

methylating agent In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These t ...

, being a synthetic equivalent of . It is a white solid that rapidly degrades upon exposure to atmospheric moisture, although it is robust enough to be weighed quickly without inert atmosphere protection.

Triethyloxonium tetrafluoroborate Triethyloxonium tetrafluoroborate is the organic oxonium compound with the formula CH3CH2)3OF4. It is often called Meerwein's reagent or Meerwein's salt after its discoverer Hans Meerwein. Also well known and commercially available is the relat ...

is a closely related compound.

Preparation and reactions

The compound is prepared by the reaction of boron trifluoride with

dimethyl ether Dimethyl ether (DME; also known as methoxymethane) is the organic compound with the formula CH3OCH3, (sometimes ambiguously simplified to C2H6O as it is an isomer of ethanol). The simplest ether, it is a colorless gas that is a useful precursor ...

and epichlorohydrin: : 4 + 2 + 3 → 3 + The salt hydrolyzes readily: : + → + + Trimethyloxonium tetrafluoroborate is generally ranked as the strongest commercially available reagent for electrophilic methylation, being stronger than methyl sulfonate esters, including

methyl triflate Methyl trifluoromethanesulfonate, also commonly called methyl triflate and abbreviated MeOTf, is the organic compound with the formula CF3SO2OCH3. It is a colourless liquid which finds use in organic chemistry as a powerful methylating agent. T ...

and

methyl fluorosulfonate Methyl fluorosulfonate, also known as magic methyl, is the organic compound with the formula FSO2OCH3. It is a colorless liquid that is used as a strong methylating agent in organic synthesis. Because of its extreme toxicity, it has largely been ...

("magic methyl"). Only the exotic dimethylhalonium reagents (, X = Cl, Br, I), methyl carboranate reagents, and the transiently-generated methyldiazonium cation () are stronger sources of electrophilic methyl. Due to its high reactivity, it is rapidly destroyed by atmospheric moisture and best stored in an inert atmosphere

glovebox A glovebox (or glove box) is a sealed container that is designed to allow one to manipulate objects where a separate atmosphere is desired. Built into the sides of the glovebox are gloves arranged in such a way that the user can place their hand ...

at −20 °C. Its degradation products are corrosive, although it is considerably less hazardous than methyl triflate or methyl fluorosulfonate, on account of its lack of volatility.

References

{{Tetrafluoroborates Methylating agents Tetrafluoroborates Oxycations Oxonium compounds