Trisilane

  • Silicon octahydride
Formula
Si3H8
Structure
Description
A colorless liquid with a repulsive odor.

Registry Numbers and Inventories.
CAS
7783-26-8
UN (DOT)
3194
Merck
12,9884

Properties.
Formula
H8Si3
Formula mass
92.32
Melting point, °C
-117.4
Boiling point, °C
52.9
Vapor pressure, mmHg
285 (25 C)
Vapor density (air=1)
3.47 (53 C)
Density
0.743 g/cm3 (0 C)
Solubility in water
Decomposes
Heat of vaporization
28.5 kJ/mol

Hazards and Protection.
Storage
Materials should be segregated by the hazards they comprise for storage. Protect the cylinders from direct sunlight, precipitation, mechanical damage, and temperatures above 55 C. Ship and store cylinders with the outlet plug and valve protective cap in place.
Protection
For handling sealed cylinders, wear safety glasses. Wear appropriate gloves when handling sealed cylinders. Use gloves and other skin protection, as assigned by a competent safety professional, when working within the secondary enclosure with the primary enclosure compromised, e.g., cylinder changing, to protect both from exposure to the material and from fire that may result from its release to the air.
Respirators
Positive pressure, full face, air supplied breathing apparatus should be used for work within the secondary containment equipment if a leak is suspected or the primary containment is to be opened, e.g., for a cylinder change. Air supplied breathing apparatus is required for response to demonstrated or suspected releases from the primary containment.
Small spills/leaks
Under the CERCLA/RCRA regulations this material is regulated as a hazardous waste or material. Therefore it must be disposed of in a licensed hazardous waste facility in compliance with EPA and other applicable local, state and federal regulations. It should be handled in a manner acceptable to good waste management practices.
Stability
risilane is less stable than silane and disilane at room temperature and atmospheric pressure.
Incompatibilities
Violently reactive with oxidizers and halogens. Trisilane has been reported as detonating in air.
Decomposition
Silicon oxide, silane, hydrogen.

Fire.
Flash Point,°C
0
Autoignition, °C
<54
Fire fighting
The only safe way to extinguish a trisilane fire is to stop the flow of liquid. If the flow cannot be stopped, allow the entire contents of the container to burn. Cool the container and surroundings with water from a suitable safe distance. Extinguishing the fire without stopping the flow of liquid may permit the formation of ignitable or explosive mixtures with air. These mixtures may propagate to a source of ignition. Excessive pressure may develop in containers exposed to fire, which may result in explosion, regardless of the cylinder's content. Containers with pressure relief devices (PRD's) may release their contents through such devices if the cylinder is exposed to fire. Containers without PRD's have no provision for controlled release and are therefore more likely to explode if exposed to fire. Positive pressure, self contained breathing apparatus is required for all fire fighting involving hazardous materials. Full structural fire fighting (bunker) gear is the minimum acceptable attire. The need for proximity, entry, and flashover protection and special protective clothing should be determined for each incident by a competent fire fighting safety professional.
Fire potential
Flammable and pyrophoric (autoigniting in air), but may form mixtures with air that do not autoignite, but are flammable or explosive.
Combustion products
Decomposition releases hydrogen.
Health
0
 
Flammability
4
 
 
Reactivity
1
 
 
Special
W

Health.
Exposure effects
The primary route of exposure at low concentrations is inhalation. At higher concentrations, the material ignites spontaneously in air, creating a thermal burn risk, but reducing the toxic inhalation hazard. Suspected to cause headache and nausea.

First aid
 
   Ingestion
This is not a normal route of exposure due to the pyrophoric nature of the material. May cause thermal burns to gastrointestinal tract. See First Aid Measures for Skin Contact and seek professional medical assistance immediately.
   Inhalation
1) Remove the affected person from the gas source or contaminated area. Note: Personal Protective Equipment (PPE), including positive pressure, self contained breathing apparatus, may be required to assure the safety of the rescuer. 2) If the affected person is not breathing spontaneously, administer rescue breathing. 3) If the affected person does not have a pulse, administer CPR. 4) If medical oxygen and appropriately trained personnel are available, administer 100% oxygen to the affected person. 5) Summon an emergency ambulance. If an ambulance is not available, contact a physician, hospital, or poison control center for instruction. 6) Keep the affected person warm, comfortable, and at rest while awaiting professional medical care. Monitor the breathing and pulse continuously. Administer rescue breathing or CPR if necessary.
   Skin
Flush with a copious stream of water while removing contaminated clothing. Continue flushing until the professional medical assistance arrives, but for no less than fifteen minutes. Treat thermal burns by assuring that affected area is cool by flushing with cool water, and then apply dry sterile dressings. If the patient is burned on the face, neck, head, or chest, assume that the airway may also have been burned and obtain professional medical assistance immediately.
   Eyes
Flush continuously with clean water until the professional medical assistance arrives, but for no less than thirty minutes. Continuation of flushing until patient is transferred to an ophthalmologist or emergency physician is recommended.

Transport.
UN number
3194
Response guide
Hazard class
4.2
Packing Group
I