The compound is prepared by the reaction of
boron trifluoride with
dimethyl ether and
epichlorohydrin: being stronger than methyl sulfonate esters, including
methyl triflate and
methyl fluorosulfonate ("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 groups. This compound is rapidly destroyed by atmospheric moisture and is best stored in an
argon atmosphere at −20 °C. The degradation products of this reagent are corrosive, although are considerably less hazardous than methyl triflate or methyl fluorosulfonate, as they do not evaporate. Trimethyloxonium tetrafluoroborate is useful for the methyl
esterification of
carboxylic acids under conditions where acid-catalyzed reactions cannot be used:{{cite journal : ==References==