I found this for mdma, maybe someone can specify the changes for amphetamine.
To a three-necked flask equipped with a dropping funnel, thermometer (into the reaction mixture), and down directed condenser (simple distillation apparatus) is added with 133g (1.72 moles) of 40% methylamine solution and 88g (1.72 moles) of 90% formic acid. The temperature is raised to 160°C by distilling out water, and 59.4 grams (0.334 moles) of piperonylacetone is added at one time. The following apparatus can be substituted for a three-neck flask and the piperonylacetone added by momentarily replacing the thermometer with a funnel. The mixture is maintained at 160-170°C for 7 hours and any ketone which distills over is periodically returned to the flask. The formyl derivative is hydrolyzed in the reaction mixture by refluxing for eight hours with 120 ml of concentrated HCl (145ml 31.5% muriatic acid). The mixture is diluted with 200 ml of water and extracted with benzene (or ether etc.) to remove water insoluble material. The aqueous solution is treated with a little charcoal, Norit (or filtered through activated charcoal from pet stores). The solution is made alkaline with ammonia (or alternatively 25% NaOH) and the oil thus produced is extracted with benzene (or ether etc.). The benzene is washed three times with water and dried with sodium sulfate or other drying agent. A stream of HCl gas is fed through the solution until no more precipitate is formed. The precipitate is filtered out and allowed to dry.
40% methylamine is the commonly available form along with methylamine hydrochloride. Basifying 116g of methylamine hydrochloride with 68.5g of NaOH in 80 ml of water will approximate the 40% solution called for. Slowly add the methylamine hydrochloride to the NaOH solution after it cools. Keep the solution cool to maximize the solubility of the methylamine.
