Description
MAPP Gas is a stabilized mixture of methylacetylene
and propadiene. Alkane and alkene
hydrocarbons are added as stabilizers. The stabilizers
serve to render the methylacetylene and
propadiene shock insensitive and to ensure that
their concentrations remain nearly uniform at all
times during vaporization of the mixture.
MAPP Gas is transported and stored as a liquid
under its own vapor pressure. Its transportation,
storage, and handling characteristics are
the same as those of liquefied petroleum gas. It
has a characteristic odor detectable at concentrations
as low as 100 ppm in air. Stabilized
liquefied MAPP Gas and MAPP Gas vapor are
insensitive to shock.
Its vapor is not subject to exothermic decomposition
from a 100-J energy source to 419°F
(215°C) and 285 psig (1970 kPa). With a probe
temperature of 825°F (441°C), the gas is stable
up to 600°F (316°C) and 1100 psig (7580 kPa).
Thus, it can be safely used up to full cylinder
pressure.
Chemical Properties
Propadiene is a colorless, flammable gas or
liquid with a sweet odor.
Chemical Properties
Allene is colorless with a sweet odor. It is a flammable gas and may cause fl ash fi re at room
temperature. Allene is the simplest member of the 1,2-diene class of compounds of hydrocarbons
of the aliphatic chemical family. It is a benzene and petroleum ether. Allenes are
not as stable as conjugated dienes or isolated dienes. Allene is slightly more strained than
the isomeric methylactylene. Allene is chiefl y used in organic synthesis. It is incompatible
with metals and oxidizing materials, therefore it is important to avoid copper and silver
and their alloys when used under high pressure or temperature.
Uses
MAPP Gas is primarily used as an industrial
fuel gas for oxygen-fuel gas cutting, welding,
heating, wire metallizing, flame hardening, soldering,
and brazing. Small amounts are used for
other diverse purposes such as mold smoking,
simulation of weapons firing, flame polishing of
plastics, special effects, and furnace atmospheres.
Uses
Organic intermediate.
Uses
- Allene is extensively used in a variety of photochemical, thermal, and transition metal-mediated cycloadditions.
- It can be lithiated to obtain allenyllithium which reacts with alkyl halides to afford terminal allenes.
- Additional application includes the preparation of reagents such as isopropenylsilanes and isopropenylstannanes by reacting with stannyl and silyl cuprates respectively.
Definition
Any hydrocarbon or hydro-
carbon derivative produced by substitution that has
two double bonds from one carbon and to two oth-
ers.
General Description
A colorless flammable gas. May become unstable. Not toxic but asphyxiation may occur because of displacement of oxygen. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.
Air & Water Reactions
Highly flammable.
Reactivity Profile
The unsaturated aliphatic hydrocarbons, such as PROPADIENE, are generally much more reactive than the alkanes. Strong oxidizers may react vigorously with them. Reducing agents can react exothermically to release gaseous hydrogen. In the presence of various catalysts (such as acids) or initiators, compounds in this class can undergo very exothermic addition polymerization reactions. Many of these compounds undergo autoxidation upon exposure to the air to form explosive peroxides. Violent explosions have occurred at low temperatures in ammonia synthesis gas units. These explosions have been traced to the addition products of dienes and oxides of nitrogen, produced from the interaction of nitrogen oxide and oxygen [Bretherick, 1995].
Health Hazard
Vapors may cause dizziness or asphyxiation without warning. Some may be toxic if inhaled at high concentrations. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire may produce irritating and/or toxic gases.
Health Hazard
Allene is a simple asphyxiant with slight narcotic properties. Exposures to allene cause
irritation to the skin and eyes, nausea, vomiting, headache, symptoms of drunkenness,
suffocation, convulsions, and coma.
Fire Hazard
EXTREMELY FLAMMABLE. Will be easily ignited by heat, sparks or flames. Will form explosive mixtures with air. Silane will ignite spontaneously in air. May polymerize explosively when heated or involved in a fire. Vapors from liquefied gas are initially heavier than air and spread along ground. Vapors may travel to source of ignition and flash back. Cylinders exposed to fire may vent and release flammable gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket.
Materials Uses
Piping systems for MAPP Gas must be made of
steel as stated in NFPA 51, Standard for the
Design and Installation of Oxygen-Fuel Gas
Systems for Welding, Cutting, and Allied Processes. Schedule 40 pipe is suitable if joints
are welded. Schedule 80 pipe is recommended
for threaded joints. In no case shall threaded
joints be welded after assembly. Fittings may be
rolled, forged or cast steel, malleable iron, or
modular iron. Gray or white cast iron fittings
must not be used.
Potential Exposure
Used in chemical synthesis and
as a component in mixtures with methyl acetylene, which
make up specialty welding gases.
Physiological effects
The toxicity of MAPP Gas is very slight, but
high concentrations (5000 ppm) can have an
anesthetic effect or cause nausea. Contact with
MAPP Gas vapor causes no adverse effects on
the eyes or skin. Contact with MAPP Gas liquid
may cause frostbite.
The strong odor of MAPP Gas (detectable at
100 ppm and objectionable at 1000 ppm)
should provide sufficient warning to prevent
exposure. The strong odor also serves as a
means of avoiding exposures above the lower
detectable odor limit in air.
storage
MAPP Gas should be treated with the same care
and caution as any other flammable gas. Cylinders
in storage or use should always be secured
in an upright position. Do not transport cylinders
in a closed vehicle.
MAPP Gas cylinder storage inside buildings,
except those in actual use, is limited to 368 lb
(167 kg). Larger quantities must be stored outside,
in a special building, or in a separate room
in accordance with NFPA 51.
MAPP Gas can be used with most commonly
available torches, hoses, and regulators. Acetylene
regulators can be used for working pressures
up to 15 psig (103 kPa). If a working
pressure of more than 15 psig (103 kPa) is required,
a suitable LP-gas regulator should be
used. If cylinders are manifolded, do not use
acetylene pigtails with dry flash arrestors. The
flash arrestors are not necessary and will impede
the flow of MAPP Gas.
Shipping
UN2200 Propadiene, stabilized, Hazard Class:
2.1; Labels: 2.1-Flammable gas. Cylinders must be trans-
ported in a secure upright position, in a well-ventilated
truck. Protect cylinder and labels from physical damage.
The owner of the compressed gas cylinder is the only entity
allowed by federal law (49CFR) to transport and refill them. It is a violation of transportation regulations to refill
compressed gas cylinders without the express written
permission of the owner.
Purification Methods
Freeze allene in liquid nitrogen, evacuate, then thaw out. This cycle is repeated several times, then the allene is frozen in a methylcyclohexane/liquid nitrogen bath and pumped for some time. It has also been purified by HPLC. [Cripps & Kiefer Org Synth 42 12 1962, Beilstein 1 IV 966.]
Incompatibilities
Extremely flammable gas or liquid.
Vapor or liquid forms explosive mixture with air.
Incompatible with oxidizers (chlorates, nitrates, peroxides,
permanganates, perchlorates, chlorine, bromine, fluorine,
etc.); contact may cause fires or explosions. Keep
away from alkaline materials, strong bases, strong acids,
oxoacids, epoxides, nitrogen oxides.
Waste Disposal
Return refillable compressed
gas cylinders to supplier. Return refillable compressed
gas cylinders to supplier. Nonrefillable cylinders should be
disposed of in accordance with local, state and federal
regulations. Allow remaining gas to vent slowly into atmo-
sphere in an unconfined area or exhaust hood. Refillable-
type cylinders should be returned to original supplier
with any valve caps and outlet plugs secured and valve
protection caps in place.
Precautions
Allene is a flammable gas and the container must be kept stored away from open flame
and smoking areas. Allene should be stored in well-ventilated areas with valve protection
caps in place. The gas cylinders should not be dragged or rolled, and the compressed gas
cylinders should not be refi lled without express written permission. Allene decomposes
violently at increased temperature/heat and/or pressure and the containers should be protected
from rupture and explosion.
GRADES AVAILABLE
MAPP Gas is available in only one grade.
