after the reaction of 2b4m with methylamine in DCM, the free base of mephedrone is washed 2-3 times with an equal volume of water. the reaction with methylamine lasts 4 hours at a temperature of 32-36C. do not bring DXM to a boil (38C), as DHM hydrolyzes when boiling, the free base will be heavily contaminated. if the temperature/time is observed, the free base will be very clean.