19624-22-7 Usage
Description
Pentaborane, also known as pentaboron nonahydride, is a nonmetallic, colorless liquid with a pungent odor resembling sour milk. It is highly flammable, corrosive, and toxic, making it a dangerous fire and explosion risk. Pentaborane decomposes at 300°F (148°C) and ignites spontaneously in air if impure. It has a boiling point of 145°F (64°C), a flash point of 86°F (30°C), and an extremely low ignition temperature of 95°F (35°C). Due to its flammability, it can ignite from ordinary objects on a hot day, such as pavement, metal on vehicles, and even the air. Pentaborane is also toxic by ingestion or inhalation and is a strong irritant. It is immiscible in water and has a four-digit UN identification number of 1380. The NFPA 704 designation for pentaborane is health 4, flammability 4, and reactivity 2.
Uses
1. Used in Rocket Propulsion:
Pentaborane is used as a rocket fuel due to its high energy content and flammability. In the 1950s, it was explored as a potential rocket fuel, but its extreme flammability and toxicity have limited its commercial use.
2. Used as a Reducing Agent in Propellant Fuels:
Pentaborane is used as a reducing agent in propellant fuels, taking advantage of its high reactivity and energy content. However, its use in this application is also limited by its hazardous properties.
3. Used in Air-Breathing Engines:
Pentaborane is used as fuel for air-breathing engines, which are engines that intake atmospheric air for combustion. Its high energy density and flammability make it a suitable candidate for this application, despite the associated risks.
Air & Water Reactions
Highly flammable. May ignite spontaneously in air [Merck 11th ed. 1989]. Slowly decomposes in water.
Reactivity Profile
Pentaborane is an extremely reactive reducing agent. Can ignite spontaneously in contact with air and many other materials. Reactions with oxygen are often violently explosive. Reacts with ammonia to form a diammoniate. Is stabilized by the formation of complexes with N, O, P, or S. Is stable in hydrocarbon solvents, but forms shock sensitive solutions in most carbonyl containing solvents.
Health Hazard
May cause death or permanent injury after very short exposure to small quantities.
Fire Hazard
Ignites spontaneously in air. Reacts violently with halogenated extinguishing agents. Boron hydrides present considerable fire and explosion hazard. They undergo explosive reaction with most oxidizing agents, including halogenated hydrocarbons. Fires tend to reignite. On decomposition, Pentaborane emits toxic fumes and can react vigorously with oxidizing materials. Avoid dimethyl sulfoxide, water, most oxidizing agents (including halogenated hydrocarbons). Avoid direct sunlight and sources of ignition, decomposes very slowly at 302. Hazardous polymerization may not occur.
Safety Profile
Poison by inhalation and intraperitoneal routes. Dangerous fire hazard by chemical reaction; spontaneously flammable in air. Dangerous explosion hazard. To fight fire, use special fire-fighting materials; water is not effective; reacts violently with halogenated extinguishing agents. Get instructions from supplier. Explosive reaction with oxygen. Forms shock-sensitive solutions in solvents containing carbonyl, ether, or ester functions; or halogens. Incompatible with dimethyl sulfoxide. Upon decomposition it emits toxic fumes of B. See also BORANES and BORON COMPOUNDS
Potential Exposure
Pentaborane is used in rocket propellants
and in gasoline additives.
Shipping
UN1380 Pentaborane, Hazard Class: 4.2; Labels:
4.2-Spontaneously combustible material, 6.1-Poisonous
materials. Inhalation Hazard Zone A.
Incompatibilities
Pentaborane is an extremely reactive
reducing agent. It can ignite spontaneously in contact with
air and many other materials. Reactions with oxygen are
often violently explosive. Reacts with ammonia to form
a diammoniate. Reacts on contact with water, oxidizers,
halogens, including halogenated hydrocarbons. May sel-heat
and ignite spontaneously in moist air, decomposes @ 150C.
Hydrolyzes slowly with heat in water to form boric acid.
Contact with solvents, such as ketones, ethers and esters form
shock-sensitive compounds. Pentaborane is stable in hydrocarbon
solvents, but forms shock sensitive solutions in most
carbonyl containing solvents. Corrosive to natural rubber,
some synthetic rubbers and to some lubricants. Avoid
dimethyl sulfoxide, direct sunlight and sources of ignition.
Check Digit Verification of cas no
The CAS Registry Mumber 19624-22-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,9,6,2 and 4 respectively; the second part has 2 digits, 2 and 2 respectively.
Calculate Digit Verification of CAS Registry Number 19624-22:
(7*1)+(6*9)+(5*6)+(4*2)+(3*4)+(2*2)+(1*2)=117
117 % 10 = 7
So 19624-22-7 is a valid CAS Registry Number.
InChI:InChI=1/B5H9/c6-2-1-3(2,6)5(1,8-3)4(1,2,7-2)9-5/h1-5H
19624-22-7Relevant articles and documents
Greenwood, Norman N.,Kennedy, John D.,Staves, John
, (1978)
Greenwood, Norman N.,Staves, John
, (1977)
Synthesis and chemical transformations of ionic octahydrotriborates: Cleavage of the B3H8- anion
Titov
, p. 1471 - 1479 (2008/10/09)
New octahydrotriborates LiB3H8·4Dn (Dn is dioxane), LiB3H8·2Dn, NaB3H 8·Dn, KB3H8·2.5Dn, [Mg(NH 3)6](B3H8)2, [Mg(Dg) 2](B3H8)2 (Dg is diglyme), [Mg(Dg)2](BH4)(B3H8), [Ca(Dg) 2](BH4)(B3H8), [Sr(Dg) 2](B3H8)2, and [C(NH 2)3]B3H8 were synthesized, and solvated salts with the B3H8- anion were prepared. It was shown that LiB3H8 forms hydrazinates of variable composition containing one to four hydrazine moles and the ammoniates LiB3H8·4NH3 and LiB3H 8·3NH3. The properties of the resulting salts and their solvates were studied. The temperature limits of the partial or complete desolvation of the solvates were established. The solubility of NaB 3H8·3Dn and tetraalkylammonium octahydrotriborates in organic solvents was studied over a wide temperature range. The heats of combustion in an oxygen atmosphere were measured, and the enthalpies of formation were calculated: ΔfH0(Me 4NB3H8) = -157.4 kJ/mol, Δy fH0(Et4NB3H8) = -262.5 kJ/mol, and ΔfH0(Bu4NB3H 8) = -443.8 kJ/mol. The destruction of the B3H 8- anion to give the BH4- ion and unstable borane B2H4 was found and confirmed experimentally for the first time. The destruction was studied in reactions of octahydrotriborates with Lewis bases (hydrazine and triphenylphosphine) and Lewis acids (AlCl3 and Al(BH4)3) and also in heat treatment. The B2H4 borane was isolated as the B 2H4·2PPh3 adduct. The reaction NaB 3H8·Dn → NaBH4 + B 5H9 + (H2 + Dn) can be conveniently used to prepare pentaborane(9) under laboratory conditions. The reaction of octahydrotriborate with aluminum chloride Bu4NB3H 8 + AlCl3 → Bu4N[Cl3Al(BH 4)] + B4H10 allows one to prepare tetraborane(10) with a fairly high yield and with a satisfactory degree of purity.
Kinetic studies of reactions of hexaborane(10) with other binary boranes in the gas phase
Attwood, Martin D.,Greatrex, Robert,Greenwood, Norman N.,Potter, Christopher D.
, p. 144 - 152 (2007/10/03)
Cothermolysis reactions of B6H10 with the binary boranes B2H6, B4H10, B5H9, and B5H11 have been studied by a quantitative mass-spectrometric technique to gain insight into the role of B6H10 in borane interconversion reactions. Except in the B6H10-B5H9 system the initial rate of consumption of B6H10 was found to be considerably more rapid than in the thermolysis of B6H10 alone, indicating that interactions were occuring. Detailed kinetic studies of the B6H10-B2H6 and B6H10-B4H10 reactions showed that the rate of consumption of B6H10 was governed in each case by the rate-determining step in the decomposition of the co-reactant, the orders being 3/2 with respect to B2H6 and 1 with respect to B4H10; a considerable increase in the conversion of B6H10 to B10H14 at the expense of polymeric solids was also observed. Added hydrogen was found to have very little effect on the reaction rates and product distributions in the cothermolysis reactions, in marked contrast to its effect on the reactions of B2H6 and B4H10 alone. The kinetic results are entirely consistent with earlier suggestion, based on qualitative observations, that the reactive intermediates {B3H7} and {B4H8} are scavenged by reactions with B6H10, and suggest strongly that this borane, unlike B6H12, plays a pivotal role in the build-up to B10H14 and other higher boranes.