Tetrafluoroboric acid dimethyl ether complex

Improved preparation. Trityl fluoroborate can be prepared conveniently by the reactions of triphenylmethyl chloride with anhydrous tetrafluoroboric acid-dimethyl ether complex in dry benzene ... 

The reaction of A -methylthio(dimethyl)amine with a two-fold excess of an alkene in the presence of trimethyloxonium tetrafluoroborate produced, in moderate yield, the l-dimethylamino-2-methylthio adduct 3, after demethylation of the intermediate ammonium salt by excess trimeth-ylamine120. More conveniently, the same product is directly obtained by using boron trifluo-ride-dimethyl ether complex as Lewis acid. 

Complexes. Silver tetrafluoroborate is insoluble in cyclohexane but very soluble in water, ether, toluene, and nitromethane, and moderately soluble in benzene and cyclohexene. - Solubility in the unsaturated hydrocarbons is attributed to n-bond formation between the unsaturated compound and silver ion. Complexes have been observed with both ir-electron donors and lone-pair donors thus Meerwein prepared stable complexes with benzene, mesitylene, cycloheptatriene, diethyl ether, dimethyl sulfoxide, and a series of acid nitriles. However, the silver tetrafluoroborate-benzene complex is reported variously as a 1 1 complex, a 1 2 complex, and as a 2 3 complex. ... 

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