3-(Dimethylamino)-1-phenylpropan-1-one hydrochloride
This synthesis is a straightforward example of a laboratory procedure for the Mannich reaction. All of the reagents are combined together and the reaction is performed in a single pot. The electrophilic iminium ion is generated by the acid-promoted condensation of formaldehyde and dimethylamine in the presence of acetophenone and is consumed as it is formed.
A solution of acetophenone (30.0 g, 28.3 mL, 0.25 mol), dimethylamine hydrochloride (26.5 g, 0.33 mol), and paraformaldehyde (9.9 g, 0.11 mol) is treated with 0.5 mL of concentrated hydrochloric acid in 40 mL of 95% ethanol. The solution is heated to reflux for 2 hours followed by rapid filtration through a preheated funnel. The warm solution is treated with 100 mL of acetone and is then allowed to cool to room temperature slowly. After cooling for 12 hours at 0 °C, the solution is filtered to afford the title compound. Alternatively the crude material can be purified via column chromatography.