Procedure:  Parr bottle

                  Dissolved 5.020 g of I in 130 mL of water and 10 mL of a 37% solution of formaldehyde in water using sonication and heat.  Added 5.025 g of 10% Pd/C.  Placed on Parr shaker at 50 psi H₂.  After 5 h, TLC (4:96 MeOH-CH₂Cl₂, UV) showed product spot at Rf 0.58.  The reaction mixture was filtered through Celite to remove the catalyst and 1.120 g of solid NaHCO₃ was carefully added to the filtrate.  The solution was concentrated by rotary evaporation to a white solid.  The product was isolated by flash chromatography on silica gel using 4:96 MeOH-CH₂Cl₂ as eluant.  The product was a white solid.

 

 ¹H NMR (CD₃OD, 300 MHz) d 7.43 (d, J = 7.1 Hz, ArH, 2H), 7.25 (dd(apparent t), J = 7.1 Hz, ArH, 2H), 7.16 (d, J = 7.1 Hz, ArH, 1H), 3.04 (b, CH₂s, 2H), 2.64 (m, CH₂s, 4H), 2.44 (s, NCH₃, 3H), 1.90 (m, CH₂s, 2H). 

 

notes

 

This reaction was also performed using the free-based zwitterion, however, it was necessary to add AcOH to successfully obtain a solution. 

 

This reaction is a method for forming the N-methyl compound without forming the N,N-dimethyl quaternary salt which is often a problem with the alkylation of amines.