0.982 g (1.03 mL, 10.0 mmol) cyclohexanone, 0.360 g (12.0 mmol) paraformaldehyde, 0.816 g (10.0 mmol) dimethylammonium chloride and 4 mL ethanol are filled in a 25 mL round bottom flask with reflux condenser and magnetic stir bar. 2 drops of conc. hydrochloric acid is added, and the mixture is heated under stirring for 4 hours under reflux. The hot solution is filtered in a round bottom flask, and the solvent is evaporated by the rotary evaporator. The residue is dissolved in 2 mL ethanol under heating. At room temperature, 20 mL acetone is added to the solution. For complete crystallization, the solution is stored overnight in the freezer compartment. The crystallized crude product 2-(Dimethylaminomethyl)-1-cyclohexanone hydrochloride is sucked off over a Buechner funnel and dried in the desiccator over silica gel.
