Methyl iodide → N-methyl-N-cyclohexylpyrrolidinium iodide

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Reaction Steps

Referring to Scheme 3 below, N-cyclohexylpyrrolidine prepared in Example 1 (1 molar equivalent) was dissolved in methanol to 0.5M concentration in a three neck reaction flask equipped with a mechanical stirrer and reflux condenser. To the methanolic solution of cyclohexylpyrrolidine, 2 molar equivalents of methyl iodide were added, and the resulting mixture was left to stir overnight. The mixture was heated to reflux and left to stir at reflux for 4 hours. The reaction was cooled down and left to stir overnight. The reaction was complete. The reaction mixture was concentrated on a rotary evaporator. The resulting tan-colored solids were dissolved in isopropyl alcohol and then precipitated out from solution by adding diethyl ether. The precipitate was filtered out and dried on a rotary evaporator at reduced pressure and in hot water bath at 80° C. to give the desired N-methyl-N-cyclohexylpyrrolidinium iodide in 86% yield. N-Methyl-N-cyclohexylpyrrolidinium iodide was converted to the hydroxide by ion-exchanging the iodide ion with hydroxide ion. In a polyethylene plastic bottle, N-methyl-N-cyclohexylpyrrolidinium iodide salt was dissolved in deionized water (1 mmol salt/10 ml H2O). Then Bio-Rad AG 1-X8 resin (1.1 g resin/mmol salt) was added and the slurry-like mixture was gently stirred overnight. The exchange solution was then filtered and a small aliquot was titrated with 0.1N HCl to give 92% yield of the N-methyl-N-cyclohexylpyrrolidinium hydroxide.

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