Reply To: Decaborane Handling

[Alchemist32]

Hi Everyone,

I am a professor specializing in boron chemistry research in areas such as synthesis and boron neutron capture therapy (BNCT). My group has a lot of experience working with decaborane, carboranes and polyhedral borate anions. Since I am also interested in alternative fusion research (outside of my own field) I wanted to add my two-cents worth to these discussions.

Please don’t consider my points as “preachy”, I just sincerely want to add my expertise as a boron chemist to your pursuits (if you find this helpful).

First, a couple of matters of safety. Decaborane is toxic, but not as much as one might think. It is so incredibly stinky that I doubt that anyone would breath in toxic quantities of the vapor without first becoming ill. Of course, ingestion of the material is another matter! (I’ve never heard of this happening). The inhalation of large doses have led to loss of consciousness, headaches and in some cases, short term amnesia. I know several chemists in the Czech Republic that use decaborane in large quantities without proper fume hoods. (while we also use huge quantities…we use great hoods!) They absolutely reek from the decaborane. It permeates their cloths, skin, hair, etc (imagine the smell of chain smokers x100). Diborane does not smell like chocolate. The closest I can describe it is really stinky napthalene, only much worse!

Decaborane will react with water to liberate hydrogen (explosion risk). However, it MUST NEVER be mixed with halogenated hydrocarbons (chloroform, carbon tetrachloride, etc.) as this will result in a massive spontaneous explosion. Back in the sixties, a pilot plant was being cleaned out using carbon-tet. In a fraction of a second, the entire plant any everyone present ceased to exist. It is stable in many dry solvents, just make sure of their identity before using.

Decaborane, as a fuel, contains much more energy than hydrocarbons. I’m certain that you are familiar with the 1950’s Navy and Air Force projects HEF and Zip where they investigated decaborane derivatives as jet and rocket fuels (read boron bomber, etc.) As such, an air-fuel mixture could easily result in a massive explosion! As it is proposed to use heated decaborane vapors here (under vacuum), extra precautions must be taken to ensure that there is no failure of the vacuum system or any other way for air to suddenly mix with the hot decaborane vapors.

I do have a suggestion that I want to throw out on the table. That is to propose using the gas diborane (B2H6), instead of decaborane. It is a gas at room temperature meaning that you will not need to heat the vacuum chamber. Like decaborane, it does undergo pyrolytic reactions at elevated temps. Of note, decaborane does readily decompose above 300 C, these polymerization reactions still occur at lower temps (only slower). While diborane is dirt cheap, decaborane costs near its weight in gold! Also, B-11 isotopically-enriched decaborane costs are astronomical! B-11 diborane would be much cheaper and easier to produce.

If you are interested in discussing the use of diborane…post a reply!