fail to synthesis methcathinone with Permanganate

Hello
I did this experiment several times and the answers were always the same.
According to the methods available on the Internet, I reacted 3 grams of ephedrine powder with potassium permanganate at 1 ° C. The reaction was performed correctly and the purple color disappeared. After filtering and adding isopropyl alcohol, after several hours, filter again and add a few Drop of chloride acid up to pH from 5 to 6. Then put the dish on the heater.The temperature is about 70 degrees centigrade. All liquid evaporated after several hours. Finally, the viscous brownish material remained in the bottom of the dish. I added some acetone to wash the excess material. I decant the acetone in another container. I was expecting the crystals to appear. But something did not happen. I repeated a few times. I even added methanol once and evaporated again. But eventually a brownish substance appeared.
Has anyone really done this synthesis?
If so, why does not give your information to others.
I only have 3 grams of ephedrine powder left.
All ephedrines are consumed in repeating this test.
This is my latest test. Please help.