Boron as a Fuel Source

1
Boron as a Fuel Source

• Advantages
• Boron is less massive than aluminum.
• Per volume boron has a heating value 60 greater
  than that of aluminum.
• Challenges
• Oxide layer on boron particles inhibits surface
  vaporization of boron particles and results in
  ignition delays.
• Combustion pathways often lead to HOBO (with less
  energy release) as opposed to the desired B2O3.
• Combustion and Flame, 1991, 83, 43-62.

2
Overcoming Challenges by Using Fluorine

• Flourine-Boron bonds are thermodynamically more
  stable than Oxygen-Boron bonds.
• The formation of Fluorine-Boron bonds avoids the
  kinetic trap that results in HOBO.
• If we can attach fluorine containing groups to
  decaborane (B10H14) we may be able to make a
  better burning boron fuel.

3
Hydroboration in Ionic Liquids

• 1-butyl-3-methylimidiazolium (bmim) or
  1-butyl-4-methylpyridium (bmpy) salts of BF4-
• Biphasic reaction (toluene/ IL) at 125 C
• In bmin, monoalkylated product is obtained 90
  yield for internal/terminal alkenes
• In bmpy, dialkylated product is formed with
  extended reaction time

J. Am.Chem. Soc. 2004, 126, 8662-8663
4
Possible Fluorinated Alkenes
1H,1H,2H-Perfluorohexene
1H,1H,2H-Perfluoro-1-Octene
Pentafluorostyrene
1,4-Divinyloctafluorobutane
5
Possible Catalysts
Ionic Liquids
Traditional catalysts
H2PtCl6
PtBr2
TiCp2(CO)2
bmim
bmpy