>>10863236 If the available form of methylamine is the aqueous solution of the free base, the following sequence can be substituted: add, in succession, 76 mL 40% aqueous methylamine, 180 mL IPA, a suspension of 50 g NaCl in 140 mL H2O that contains 25 mL 25% NaOH, 53 g 3,4-methylenedioxyphenylacetone, and finally 350 mL IPA. The exothermic reaction was kept below 60 ° C with occasional immersion into cold water and, when it was thermally stable, it was allowed to stand until it had returned to room temperature with all the insolubles settled to the bottom as a grey sludge. The clear yellow overhead was decanted and the sludge removed by filtration and washed with MeOH. The combined decantation, mother liquors and washes, were stripped of solvent under vacuum, the residue suspended in 2400 ml of H2O, and sufficient HCl added to make the phase distinctly acidic. This was then washed with 3x75 mL CH2Cl2, made basic with 25% NaOH, and extracted with 3x100 mL of CH2Cl2. After removal of the solvent from the combined extracts, there remained 55 g of an amber oil which was distilled at 100-110 ° C at 0.4 mm/Hg producing 41 g of an off-white liquid. This was dissolved in 200 mL IPA, neutralized with about 17 mL of concentrated HCl, and then treated with 400 mL anhydrous Et2O. After filtering off the white crystals, washing with an IPA/Et2O mixture, (2:1), with Et2O, and final air drying, there was obtained 42.0 g of 3,4-methylenedioxy-N-methylamphetamine (MDMA) as a fine white crystal. The actual form that the final salt takes depends upon the temperature and concentration at the moment of the initial crystallization. It can be anhydrous, or it can be any of several hydrated forms. Only the anhydrous form has a sharp mp; the published reports describe all possible one degree melting point values over the range from 148-153 ° C. The variously hydrated polymorphs have distinct infrared spectra, but have broad mps that depend on the rate of heating.
