Pentaborane

Structural formula
General
Surname	Pentaborane
other names	Pentaboron monahydride nido-pentaborane
Molecular formula	W 5 H 9
Brief description	colorless liquid with an unpleasant odor
External identifiers / databases
CAS number 19624-22-7 EC number 243-194-4 ECHA InfoCard 100.039.253 Wikidata Q417437
properties
Molar mass	63.13 g mol −1
Physical state	liquid
density	0.61 g cm −3
Melting point	−46.7 ° C
boiling point	58.4 ° C
Vapor pressure	220 mbar (20 ° C)
solubility	decomposes in water
safety instructions
GHS hazard labeling no classification available
MAK	Switzerland: 0.005 ml m −3 or 0.01 mg m −3
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Pentaborane , more precisely pentaborane (9) , is a chemical compound from the borane group .

Extraction and presentation

Pentaborane (9) can be obtained by thermolysis of diborane , whereby thermolabile tetraborane is formed as an intermediate product which, with the diborane present, converts to pentaborane (11) (B ₅ H ₁₁ ) and this in turn partially converts to pentaborane (9).

${\displaystyle \mathrm {6\ B_{5}H_{11}\longrightarrow 4\ B_{5}H_{9}+5\ B_{2}H_{6}} }$

properties

Pentaborane (9) is a self-igniting, volatile, colorless liquid with an unpleasant odor, which decomposes in water.

use

Pentaborane (9) was studied as a rocket fuel in the US in the late 1950s and by Glushko in the USSR in the 1960s . As with other fuels containing fluorine and boron, the many problems of handling and safety prevented their use.

safety instructions

If pentaborane comes into contact with alcohols, ammonia, oxygen, esters, ethers, halogenated hydrocarbons and ketones, there is a risk of explosion. It can also react dangerously when exposed to water, air and heat, producing boron compounds and hydrogen.

Individual evidence

1. ↑ ^{a b c d e f g h} Entry on pentaborane (9) in the GESTIS substance database of the IFA , accessed on August 24, 2011(JavaScript required) .
2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
3. ↑ Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 19624-22-7 or pentaborane ), accessed on November 2, 2015.
4. ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 , p. 1003.
5. ↑ N2O4 / Pentaborane in the Encyclopedia Astronautica (English)

Web links

• Pentaborane - Taming the Dragon
• K. Hedberg, ME Jones, V. Schomaker: The Structure of Stable Pentaborane. In: Proceedings of the National Academy of Sciences . Volume 38, Number 8, August 1952, pp. 679-686, ISSN  0027-8424 . PMID 16589161 . PMC 1063634 (free full text).
• NASA: Performance of pentaborane, pentaborane - JP-4 fuel mixtures, and trimethylborate azeotrope fuel in a full-scale turbojet engine (November 20, 1956)