There was a process given on Rhodium's page where dimethylamine is synthesized by refluxing DMF with HCl for over 6h and doing an a/b extraction. However, in Rhodiums Methylamine FAQ, another synthesis is given. Simply react methylamine HCl with formaldehyde. Now doesn't that sound better? My question is how I should go about doing this. Could I just boil methylamine HCl in an access of paraformaldehyde in water above 115deg for a few hours? What would you suggest? Here's the section from Rhodium's FAQ:
Methylamine hydrochloride condenses with formaldehyde to form dimethylamine. If formaldehyde is present in excess, at least some of the methylamine is converted to dimethylamine. If too little formaldehyde is present, the methyleneimine polymerizes to its trimer, (CH2=NH)3. Trimethylamine is never formed, as long as the temperature of the solution never exceeds 110°C. With an excess (4 moles) of formaldehyde, enough water and a reflux temperature of 115°C, dimethylamine is the main product, as the temperature rises, more dimethylamine is formed. Dry heating of paraformaldehyde and ammonium chloride produces trimethylamine through reaction of dimethylamine with formaldehyde, giving rise to tetramethylmethylenediamine and formic acid, and the base further reacts with HCl, giving trimethylamine hydrochloride and methyleneimine hydrochloride. A mixture of HMTA and HCl boils between 105 and 110°C, while NH4Cl/CH2O boils at 115°C. No temperature control is really necessary in the former case, as long as your heating plate isn't too hot. If the reaction is carried out at a lower temperature, less dimethylamine is formed, and the yield is higher. Vacuum reflux and distillation can yield at least 95% yield, in contrast to the 45% gotten at 104°C.