Trimetüüloksüoniumtetrafluoroboraat

Trimetüüloksüoniumtetrafluoroboraat is a chemical compound with the formula [(CH3)3O]BF4. It is a salt consisting of the trimethyloxonium cation and the tetrafluoroborate anion. This compound is notable for being a stable, isolable source of the trimethyloxonium cation, which is a powerful electrophile.

The preparation of trimethyloxonium tetrafluoroborate typically involves the reaction of trimethyl borate with boron trifluoride in the presence of an alkylating agent, such as methyl triflate. Alternatively, it can be synthesized by the reaction of dimethyl ether with boron trifluoride and methyl triflate. The compound is usually obtained as a white, crystalline solid that is hygroscopic and sensitive to moisture.

Trimetüüloksüoniumtetrafluoroboraat is primarily used in organic synthesis as a methylating agent. It is a strong methylating agent that can effectively transfer a methyl group to various nucleophiles, including alcohols, phenols, carboxylic acids, and amines. Its electrophilic nature makes it useful for O-methylation, N-methylation, and S-methylation reactions. Due to its high reactivity, it is often employed when less reactive methylating agents are ineffective.

In reactions, trimethyloxonium tetrafluoroborate is typically handled under anhydrous conditions to prevent decomposition. Its use is generally confined to laboratory settings due to its cost and handling requirements. The reaction products depend on the nucleophile and reaction conditions, with the tetrafluoroborate anion serving as a non-nucleophilic counterion.