Hydrochloric Acid → Dimethylamine, hydrochloride

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Reaction Steps

First, 6.83 g of a 50% by mass aqueous dimethylamine solution (dimethylamine: 75.9 mmol) was added to a 100-ml two-necked flask. Next, 8.19 g of a 35% by mass aqueous solution of hydrochloric acid (hydrochloric acid: 78.9 mmol) was added to a 100-ml dropping funnel. Subsequently, the dropping funnel was set to the two-necked flask, and then the aqueous solution of hydrochloric acid was added dropwise to the aqueous dimethylamine solution under ice-cooling. Thus, dimethylamine hydrochloride was prepared in the two-necked flask. Next, 2.78 g (92.4 mmol) of paraformaldehyde as the formaldehyde derivative and 9.0 g (61.6 mmol) of α-tetralone as the carbonyl compound were further added to the two-necked flask. Note that the volume of the mixture made of water and paraformaldehyde present in the two-necked flask was 25 mL, and the concentration of hydrochloric acid (HCl) in the mixture was 0.12 mol/L. Subsequently, a bulb condenser was set to the two-necked flask, and then the inside of the two-necked flask was replaced with nitrogen. Thereafter, the two-necked flask was immersed in an oil bath of 90° C., and heated for 4 hours with stirring. Thus, a reaction liquid was obtained. Note that the thus obtained reaction liquid was subjected to HPLC analysis for components in the reaction liquid. As a result, the conversion of α-tetralone was found to be 99%, and the yield (HPLC yield) of N,N-dimethylaminomethyl-1-tetralone hydrochloride (the Mannich base) was found to be 95%.

Provenance & Evidence