From: AHAHMA%kontu.utu.fi@ssyx.ucsc.edu Subject: Peroxides Date: 6 Mar 90 18:14:25 GMT > Any answers to the questions posed above or any other interesting >info about H2O2 would be greatly appreciated. Concentration by distillation should be carried out under vacuum to prevent decomposition of the peroxide. As the concentration approaches 70 % and over there will be a considerable risk of an explosion. Further, you would need a fractionating apparatus to get some yield. The apparatus must be extremely clean, even traces of metallic impurities may cause hydrogen peroxide to decompose violently.(Cu,Co,Ni,Fe,Mn at least) The peroxide is quite difficult to detonate, unless it is over 85 % and/or hot, like during distillation. But, detonating such high concentrated peroxide would be just a waste of a good raw material. A better idea is to make some organic peroxide of it. Besides, you will need only 30 % H2O2 to make for example acetone peroxide. Acetone peroxide is very sensitive to shock, friction and especially sparks and flame. It must be handled with great care and it MUST NOT be stored more than a few days. Right after preparation it contains considerable amounts of water (20 to 30 % by weight), that makes it more insensitive and it is possible to handle it. However, it loses this probably occluded water gradually and becomes extremely sensitive, even more sensitive than mercury fulminate. If the peroxide is dry, it always explodes with a great violence regardless of confinement. Also, it sublimes at 56 C and slowly crystallizes inside a closed vessel at room temperature. These crystals are dangerous to even touch. They adhere very tight on the walls of the vessel and if you try to scratch them off, they don't like it at all. One crystal is very capable of igniting the whole amount in the container. This is also why you must not put this peroxide in screw-cap containers, there may be crystals between there. Guess what happens, if you then screw the cap! Right after preparation (air dry, dried at ROOM TEMPERATURE) it burns with a great flash, a teaspoonful makes a fire ball of about 0.5 meters in diameter, if lit unconfined. It looks quite spectacular, just like car explosions in the movies. I actually call this peroxide a movie explosive, since the flash makes only a slight and deep boom. Even the flame created won't burn anything. NOTE: If the peroxide is under a slightest cover, for example inside aluminum foil, it will always detonate on ignition, even if it contains some water. There are also many other organic peroxides, that are similar to acetone peroxide. To mention some I've tried: cyclohexanone, methylethylketone, cyclopentanone peroxides and HMTD. HMTD can be made directly with 3 % hydrogen peroxide, but the yield is low and the product crystallizes in big crystals, that are dangerous. 3P